FLIR , IRST in air to air mission

Unread postPosted: 28 Oct 2012, 20:22
by falconedge
can system like EOTS , DAS do the job of radar in air to air mission ?:roll: i can think of some of their advantages :
+passive
+can detected stealth targets
+ with laser finder range they can give info about the angle , altitude , range to target (not sure if that enough for a target lock :?:)
but they also have some disadvantages
+unable to measure the velocity of targets
+affected by weather
and what different between IRST and FLIR or they are the same ? :?:

RE: FLIR , IRST in air to air mission

Unread postPosted: 28 Oct 2012, 21:13
by SpudmanWP
IRSTs have been doing it for years. A good IRST can be the only sensor used in an A2A engagement. With a laser an IRST can measure velocity.

ISRTs tend to scan quicker.

RE: FLIR , IRST in air to air mission

Unread postPosted: 28 Oct 2012, 22:02
by count_to_10
They also have a relatively limited range.

Unread postPosted: 28 Oct 2012, 22:38
by Gums
Salute!

Flew Deuces and VooDoos with IRST systems back in the 60's.

- range was not a biggie for multi-engine buff-type targets, even head on. Fighters were harder to acquire/track unless you had a beam or stern aspect, or they were in burner. OTOH, our systems could still find them at ranges allowing a good missile shot.

Best mode we had was IR track and radar still in search mode. The buff EWO didn't see us lock up, didn't know our range, but we had his range and could launch the IR missile when at the best range.

- After 40 years, we have incredibly better IR sensors. Hell, by late 70's we had the AIM-9L with a head on capability against non A/B fighters. Stuff today prolly ten times better. We can also scan quicker than our old mechanical sensor positioning systems. Then there's a "stare" mode if you have a clue where the threat is. The photon impacts add up and voila!

- The airborne IRST systems used to be different than the FLIR, but maybe not anymore. In Desert Storm, the Warthogs used their Mavericks to find and kill tanks at night. Pilots told me that the barrels looked like toothpicks against the cooler sand late at night when things cooled down.

- I ain't gonna get into current range and geolocation stuff. But " there must be fifty ways to...."

Gums sends...

Unread postPosted: 28 Oct 2012, 23:04
by firstimpulse
Great points as always, Gums. :)

http://www.youtube.com/watch?v=cPKw3RksCcI
Skip to 3:30. The F-35's IR systems are marketed to be of extreme use both in BVR and WVR engagements, and I believe alot of the hype. It pretty much makes the dogfight into a video game, since everything is visible (the HMD system even lets you look through the floor to see a target). This could be countered by the new IR-stealth systems on craft like the Raptor, but regardless it remains a potentially incredible tool.

Unread postPosted: 29 Oct 2012, 01:09
by SpudmanWP
While the F119's IR optimised nature will help in the tail-chase, it will not make much of a difference from the front or sides.

Unread postPosted: 29 Oct 2012, 02:41
by LinkF16SimDude

:lol: Love the over-the-shoulder missile shots at 3:38.

Unread postPosted: 29 Oct 2012, 04:45
by sprstdlyscottsmn
They SHOULD be able to get weapons grade solution via coordinationg the respective azimuth and elevation pictures of the tracks between wing pairs. One of the reasons why its good the these guys to fly several miles apart, better angular resolution.

Unread postPosted: 29 Oct 2012, 11:27
by falconedge
sprstdlyscottsmn wrote:They SHOULD be able to get weapons grade solution via coordinationg the respective azimuth and elevation pictures of the tracks between wing pairs. One of the reasons why its good the these guys to fly several miles apart, better angular resolution.

Well i think they could do the job much easier by using laser finder range , laser are quite powerful now a day , if iam not wrong they can reach 70-80 km :)

Unread postPosted: 29 Oct 2012, 19:50
by Scorpion82
IRST systems can gather a similar range of data as radars, but they do so with less accuracy and are adversely affected by background and atmospheric conditions. A laser is accurate but is effective against a single target only as of now. Lasers are active as well and their range performance is equally affected by atmospheric conditions like IRSTs. Laser is essentially also just an EM wave like visible light or IR. It's just a different wavelength.

Unread postPosted: 05 Jul 2013, 06:13
by beepa
Check out the SU-35 in FLIR. Looks like she runs pretty hot, might make a good target someday.

http://youtu.be/x3zX4QI-BT4

Unread postPosted: 05 Jul 2013, 19:58
by neurotech
Scorpion82 wrote:IRST systems can gather a similar range of data as radars, but they do so with less accuracy and are adversely affected by background and atmospheric conditions. A laser is accurate but is effective against a single target only as of now. Lasers are active as well and their range performance is equally affected by atmospheric conditions like IRSTs. Laser is essentially also just an EM wave like visible light or IR. It's just a different wavelength.

Modern AESA radar has a longer effective range than a IRST system against a fighter target. I agree that atmospheric conditions do adversely effect IRST range considerably.

F-15C AESA radar 100NM+ on good day with a 1m2 target. The Russians claim even longer ranges with their Su-35 Irbis-E radar. F-35 EOTS is good to about 50-80NM with a fighter sized target. I'm not sure the range of the EOTS rangefinder laser, but I'd be surprised if its more than 20NM effective range.

Unread postPosted: 05 Jul 2013, 21:33
by FlightDreamz
can system like EOTS , DAS do the job of radar in air to air mission ?

One mans opinion (and I have never worked on, flown or been in near around a military aircraft aside from airshows and museums) in a word - <b>YES!</b>
Just look at the conniption fits and flaming hoop's the Navy (and Boeing) are jumping through trying to "cludge" an Infrared Search and Track system onto the F/A-18 Hornet ("super" or otherwise). :doh:
See <a href="http://www.f-16.net/f-16_forum_viewtopic-t-8585.html"> this thread</a>.
See also <a href="http://40yrs.blogspot.com/2009/03/worldwide-war-pigs-drop-tank-irst-tests.html">this blog</a> and http://www.flightglobal.com/news/articl ... ef-361304/

Image
Mounting an I.R.S.T. in the front end of an F/A-18's centerline fuel tank. REALLY!

Not to mention, the idea of mounting an I.R.S.T. on the U.S.A.F. F-15C has come (and gone, thanks to budget trouble and this was <i>before</i> sequestration!) at least twice by my count.
The U.S. wouldn't pursue this if it didn't have value (not to mention the SU-27 Flanker, MiG-29 Fulcrum, Eurofighter Typhoon, France's Rafale, etc. etc.)!

Unread postPosted: 07 Jul 2013, 12:38
by uclass
IRST is an invaluable asset at close-medium range against low RCS aircraft. A radar scan is too narrow below 40km and a wider angle system is required for initial detection.

Re: FLIR , IRST in air to air mission

Unread postPosted: 29 Jul 2015, 13:27
by hornetfinn
It seems there is some discussion regarding IRST systems here and there and found this old topic which seems to best fit the discussion.

First, I’d like to go through some basic information regarding IRST systems and how they work.

First, there are several different types of IRST sensors in use in different fighters. The technology is similar also in different missiles and also FLIR systems (imaging sensors only).

1. Non-imaging uncooled IRST systems. These types of sensors were used in Western fighter IRSTs from 1950s onwards and are still used in MiG-29 OLS-29 systems. These systems have very poor range due to low sensitivity (by modern standards) and can only give indication about direction to some heat source. They are unable to tell the range (without laser) and cannot identify targets as they cannot create images but just detect increase in IR radiation in some direction. These systems also cannot effectively detect and track multiple targets. Similar sensor was used in many older IR seeking missiles.
2. Non-imaging cooled IRST systems. These types are used in for example Su-27 variants (OLS-27 to OLS-35). Some old Western IRST systems might have been this type also. These have much better sensitivity and thus longer range. Otherwise they share similar limitations as the older systems. Many IR seeking missiles have used this type of seeker like AIM-9L/M, R-73, Igla and Stinger. However there is difference in cooling and seeker systems and older missiles using this type had much inferior performance to later missiles.
3. Imaging, uncooled IRST systems. These types have not been used in fighter IRST systems as the cost of using cooling is fairly low compared to other costs involved (for fighter use) and because cooling improves performance a lot. In the future these types might be used in some applications as their performance has improved significantly recently, although will never reach the performance of cooled imaging systems. They easily beat both uncooled and cooled non-imaging systems though in almost every respect. They have decent range and as they are imaging, can also recognize and identify targets close enough to have enough pixels from them. They can also do passive ranging and can detect/track large number of targets simultaneously. These are used in some missiles though, as they are much cheaper and smaller than cooled systems and have performance good enough for many missile applications.
4. Imaging, cooled IRST systems. These types are used in modern Western IRSTs like Pirate, FSO and EOTS. These outperform all other types handily and have all the capabilities of imaging uncooled systems but offer much better sensitivity and thus better range and target discrimination abilities.

Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale. Compared to scanning arrays, modern staring arrays have higher sensitivity, longer range and better reliability (no mechanical components) and higher frame rate with better image quality. They are also gotten cheaper as manufacturing techniques has improved. Scanning arrays are no longer really used in new products any more as staring arrays can do everything they can but better.

I think Western countries abandoned IRST because non-imaging systems weren’t really that good and radar systems were very effective. As new imaging IRST technology has emerged small and cheap enough to be installed on fighter aircraft, IRST systems have suddenly become widespread. I think new systems will be found to be very effective even in air-to-air combat, although they do have their limitations. Especially the F-35 combination of DAS and EOTS, combining short-range wide field of view and long-range narrow field of view systems and having sensor fusion between all of the sensors to automate functionality, will likely be very effective.

Re: FLIR , IRST in air to air mission

Unread postPosted: 29 Jul 2015, 15:07
by Dragon029
hornetfinn wrote:Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale.


Just curious; is the difference between a scanning and staring array to do with having the sensor itself mechanically gimbaling in a housing / seeker head, or is this more of a rolling vs global electronic shutter deal?

Re: FLIR , IRST in air to air mission

Unread postPosted: 30 Jul 2015, 09:12
by neurotech
Dragon029 wrote:
hornetfinn wrote:Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale.


Just curious; is the difference between a scanning and staring array to do with having the sensor itself mechanically gimbaling in a housing / seeker head, or is this more of a rolling vs global electronic shutter deal?

The F-35 DAS is uses 6 CCD image sensors. These are basically IR sensitive video cameras.
http://www.intevac.com/wp-content/uploa ... sheet2.pdf

Most FLIR systems have used camera tubes or CCD sensors of some type. IRST systems typically use scanning sensors (some are flat arrays that move up and down, others use a 2D scan reflected into a sensitive photodiode) along with a laser for spotting/rangefinding. I'm pretty sure the Russian OLS uses a 2D scan. According to fulcrumflyer the OLS was practically useless. Another US MiG-29 pilot said it was very good at locating the bandit, assuming the jet was pointed at the bandit. The OLS had been upgraded between a Fulcrum-A and Fulcrum-C aircraft.

For a summary of NAV/FLIR vs IRST, see https://en.wikipedia.org/wiki/LANTIRNAN/AAQ-37

For the record, the F-35 DAS (AN/AAQ-37) is significantly more effective at locating low RCS targets, because of its spherical coverage. I'm not sure if the DAS can accurately detect range, but should be able to cue an AIM-9 without radar lock. This will be the "killer" feature of the F-35 (with AIM-9X missiles) should someone think declaring a "line of death" with a Sukhoi is a good idea. Coincidentally, VAdm. David Venlet who ran the JSF program before LTG Bogdan, was the RIO who downed one of the Su-22s over the Gulf of Sidra.

Re: FLIR , IRST in air to air mission

Unread postPosted: 30 Jul 2015, 09:28
by hornetfinn
Dragon029 wrote:
hornetfinn wrote:Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale.


Just curious; is the difference between a scanning and staring array to do with having the sensor itself mechanically gimbaling in a housing / seeker head, or is this more of a rolling vs global electronic shutter deal?


It's very much like rolling vs global electronic shutter type of difference. Basically in scanning arrays there is a linear array of detectors arranged to 1 to few rows (2 to 4 being common). The linear array is then scanned across the scene to develop a single image or frame. So, it's quite similar to rolling shutter as the whole scene is captured within some time-frame . In staring array there is 2-dimensional array (like 1024x1024) of detectors which are self-scanned electronically. So it's quite similar to global shutter as the whole scene is captured exactly at the same time.

Because thermal cameras are mostly basically videocameras operating in infrared, they mostly use global shutter type of operation (staring arrays or CCD). Basically it's possible and easier to produce higher resolution images (high pixel count) with staring arrays with less noise (better image quality and uniformity) and have no issues with fast movement of camera or target (no image smear, skew of wobble). These things make staring arrays preferable nowadays along with lower costs. Things were different for example when Eurofighter Pirate sensor was developed (1990s). Then it was technologically easier to produce high performance imaging infrared system with scanning array as it was difficult to manufacture high resolution staring arrays. If Pirate would be developed today, it would most likely use staring array.

Re: FLIR , IRST in air to air mission

Unread postPosted: 30 Jul 2015, 10:33
by hornetfinn
Passive ranging with IR sensors is an area where quite a lot of research and development has been done. For example there are a lot of patents for passive ranging. Just google "passive ranging infrared patents" and you'll find a lot of patents by the usual operators like Raytheon, Eads, Thales, Saab, Israeli Aircraft Industries, Northrop Grumman, Textron Systems Corp etc.

It seems like accurate ranging can be done when enough pixels are available of the target along with good image processing and threat libraries. I'd say EOTS can give accurate passive ranging data from even distant objects as it likely has very narrow field of view (to work as targeting system for A/G weapons) along with high resolution and sensitive sensor which is connected to sensor fusion engine. It likely easily beats any previous sensor system due to these as previous IRST systems had fairly wide field of view even with narrowest ones (not enough space for more powerful optics). DAS will not be able to do accurate ranging besides short ranges (basically visual range) as it has very wide field of view (over 90 degrees) and even with very high resolution sensor can not get enough pixels from targets from longer range to do accurate ranging. Of course for longer ranged ranging and identification there is always EOTS.

Re: FLIR , IRST in air to air mission

Unread postPosted: 30 Jul 2015, 11:31
by hornetfinn
neurotech wrote: According to fulcrumflyer the OLS was practically useless. Another US MiG-29 pilot said it was very good at locating the bandit, assuming the jet was pointed at the bandit. The OLS had been upgraded between a Fulcrum-A and Fulcrum-C aircraft.


MiG-29 uses the least advanced IRST system, uncooled non-imaging sensor which has poor range, poor sensitivity and does not work well in many difficult backgrounds (sea, ground, clouds etc). It's basically 1950s sensor technology, so it's not difficult to believe it's not very effective system. Su-27 OLS-27 was major improvement as it has cooled sensor and thus has much better range (especially head-on) and likely works much better against difficult backgrounds. OLS-35 is better still, but it's a far cry from modern imaging IRST systems like EOTS or Pirate. It can only track (Sukhoi says follow) four targets at once while Pirate can track 200 and EOTS possibly lots more due to having more processing power available. EOTS also more than likely outranges Pirate quite handily as it uses newer technology meaning more sensitive sensor with higher resolution and better image quality and uniformity. I say it's very possible that EOTS has twice the range of Pirate in similar conditions against similar target.

Re: FLIR , IRST in air to air mission

Unread postPosted: 30 Jul 2015, 13:13
by hornetfinn
Some basic things about IR sensors:

Sensitivity. Basically sensitivity tells us how weak signals (how little infrared radiation or how cold target is) can be detected. Since IR radiation travels one-way only, sensitivity affects range similarly to RWR or ESM systems (square root). Basically having four times more sensitive IR sensors gives twice the range in the same conditions. Nine times more sensitive sensor gives three times the range. Modern staring cooled sensors usually have sensitivity (NETD) of 10 to 25 mK. Scanned sensors have had sensitivity of about 100 to several hundred mK, basically about an order of magnitude higher. This is because scanning system has a lot less time to handle a single pixel (integration time which is somewhat similar to shutter speed in regular cameras) compared to staring system. So staring sensors can have 2-3 times longer range than scanned sensors.

IR bands. There are basically SWIR, MWIR and LWIR bands (short, medium and long wave). Each of these bands have their own pros and cons. MWIR is usually used in FLIR systems as it offers best overall performance in many conditions (like clear weather, hot and humid conditions). It offers much better resolution than LWIR using similar technology and is much more sensitive to temperatures that vehicles and aircraft emit. LWIR works better for cold targets against cold background and LWIR also penetrates certain weather conditions better (rain, heavy fog, clouds). However these are usually offset by MWIR sensor higher sensitivity against intended targets of IRST systems. SWIR is not usually used as it's not emitted but rather reflected. So it need some source of SWIR light for sensor to work. These sources are the same as visible light (stars, sun, moon, active illumination with laser/lamps). SWIR is also easily absorbed and scattered and usually has nowhere as long range as MWIR or LWIR systems.

QWIP. QWIP is good solution for many applications, but main problem is very long integration time required to have similar detection performance to InSb or HgCdTe sensors. This means they have to give either frame rate or sensitivity to achieve otherwise similar performance. This is why most high-end military applications don't use QWIP technology, although it seems otherwise good.

Re: FLIR , IRST in air to air mission

Unread postPosted: 31 Jul 2015, 13:14
by hornetfinn
Latest IRST/FLIR systems like EOTS and podded systems with 3rd gen staring arrays will likely have very impressive detection and tracking ranges. For example these documents have interesting information:

https://www.google.fi/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAAahUKEwiwltStp4XHAhUDAXMKHYWdB8o&url=http%3A%2F%2Fwww.dtic.mil%2Fcgi-bin%2FGetTRDoc%3FAD%3DADA481411&ei=lGG7VbD8IYOCzAOFu57QDA&usg=AFQjCNGgptw8MO8yIfdZ58h1lY-4q4URhg&bvm=bv.99261572,d.bGQ

http://www.wat.edu.pl/review/optor/14(1)1.pdf

http://antonirogalski.com/wp-content/uploads/2011/12/Third-generation-infrared-photodetector-arrays.pdf

It seems like 3rd gen MWIR systems usually have about 2-3 times longer ranges compared to 2nd generation FLIR systems. Technologically for example Pirate and targeting pods of 1990s are mostly 2nd generation IR technology. EOTS and DAS use 3rd gen MWIR system. I think many people will be surprised how powerful system EOTS+DAS is in air-to-air combat.

Re: FLIR , IRST in air to air mission

Unread postPosted: 31 Jul 2015, 16:08
by spazsinbad
Thanks for the URLs 'hornetfinn'. Sometimes even though I know the characters (HTML space would be one) using them in text strings does not work so I'm stuck with a very long google string but usually the DTIC ADA ones are easy enough so the long GOOGLE string URL above is:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA481411 (PDF 0.25Mb)

Re: FLIR , IRST in air to air mission

Unread postPosted: 31 Jul 2015, 17:06
by eloise
subsonic fighter actually have significantly less IR signature than the supersonic one ( iam not even talking about effect of afterburner here )
Image
Image

Re: FLIR , IRST in air to air mission

Unread postPosted: 03 Aug 2015, 09:22
by hornetfinn
spazsinbad wrote:Thanks for the URLs 'hornetfinn'. Sometimes even though I know the characters (HTML space would be one) using them in text strings does not work so I'm stuck with a very long google string but usually the DTIC ADA ones are easy enough so the long GOOGLE string URL above is:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA481411 (PDF 0.25Mb)


Thanks for the tip. I was wondering why it had so long URL... :)

Re: FLIR , IRST in air to air mission

Unread postPosted: 11 Sep 2018, 20:16
by falcon.16
hornetfinn wrote:It seems there is some discussion regarding IRST systems here and there and found this old topic which seems to best fit the discussion.

First, I’d like to go through some basic information regarding IRST systems and how they work.

First, there are several different types of IRST sensors in use in different fighters. The technology is similar also in different missiles and also FLIR systems (imaging sensors only).

1. Non-imaging uncooled IRST systems. These types of sensors were used in Western fighter IRSTs from 1950s onwards and are still used in MiG-29 OLS-29 systems. These systems have very poor range due to low sensitivity (by modern standards) and can only give indication about direction to some heat source. They are unable to tell the range (without laser) and cannot identify targets as they cannot create images but just detect increase in IR radiation in some direction. These systems also cannot effectively detect and track multiple targets. Similar sensor was used in many older IR seeking missiles.
2. Non-imaging cooled IRST systems. These types are used in for example Su-27 variants (OLS-27 to OLS-35). Some old Western IRST systems might have been this type also. These have much better sensitivity and thus longer range. Otherwise they share similar limitations as the older systems. Many IR seeking missiles have used this type of seeker like AIM-9L/M, R-73, Igla and Stinger. However there is difference in cooling and seeker systems and older missiles using this type had much inferior performance to later missiles.
3. Imaging, uncooled IRST systems. These types have not been used in fighter IRST systems as the cost of using cooling is fairly low compared to other costs involved (for fighter use) and because cooling improves performance a lot. In the future these types might be used in some applications as their performance has improved significantly recently, although will never reach the performance of cooled imaging systems. They easily beat both uncooled and cooled non-imaging systems though in almost every respect. They have decent range and as they are imaging, can also recognize and identify targets close enough to have enough pixels from them. They can also do passive ranging and can detect/track large number of targets simultaneously. These are used in some missiles though, as they are much cheaper and smaller than cooled systems and have performance good enough for many missile applications.
4. Imaging, cooled IRST systems. These types are used in modern Western IRSTs like Pirate, FSO and EOTS. These outperform all other types handily and have all the capabilities of imaging uncooled systems but offer much better sensitivity and thus better range and target discrimination abilities.

Imaging sensors can be further divided to scanning and staring arrays. Scanning arrays have been used in earlier FLIR/IRST systems (Pirate, AN/AAAS-42, many FLIR systems) but staring arrays have really taken over during the last decade. EOTS and DAS use staring arrays as do many later targeting pods and for example DDM-NG in Rafale. Compared to scanning arrays, modern staring arrays have higher sensitivity, longer range and better reliability (no mechanical components) and higher frame rate with better image quality. They are also gotten cheaper as manufacturing techniques has improved. Scanning arrays are no longer really used in new products any more as staring arrays can do everything they can but better.

I think Western countries abandoned IRST because non-imaging systems weren’t really that good and radar systems were very effective. As new imaging IRST technology has emerged small and cheap enough to be installed on fighter aircraft, IRST systems have suddenly become widespread. I think new systems will be found to be very effective even in air-to-air combat, although they do have their limitations. Especially the F-35 combination of DAS and EOTS, combining short-range wide field of view and long-range narrow field of view systems and having sensor fusion between all of the sensors to automate functionality, will likely be very effective.


Nice post, but i have a doubt.

I see OLS-35 tells it has TV+IR video. So really it would be similar to FSO or Pirate system. Or i am wrong?

Look the next picture.


Image

Re: FLIR , IRST in air to air mission

Unread postPosted: 12 Sep 2018, 03:57
by smsgtmac
You just dropped a graphic that is probably in these boards more than you'd find in any stack of pamphlets a Russian marketing talking head ever passed out at a trade show...in a three-year-dead thread.
20160702152544-2dece1cf.jpg

Might I suggest messaging 'hornetfinn' direct and ask him? He could have loaned you his copy ( viewtopic.php?p=303399#p303399 ) if you needed it.
BTW: Video is an output format/signal to MFDs, not necessarily of a unadulterated received 'image', so don't interpret what I'm saying as it not worthy of an answer.

Re: FLIR , IRST in air to air mission

Unread postPosted: 12 Sep 2018, 06:34
by hornetfinn
smsgtmac wrote:BTW: Video is an output format/signal to MFDs, not necessarily of a unadulterated received 'image', so don't interpret what I'm saying as it not worthy of an answer.


Just no continue this thread necromancy... :devil:

What you said is definitely true. AFAIK, OLS-35 still has just heat seeking system and not thermal imaging system. It does have daylight TV system which allows target identification in good daylight conditions. Video is definitely just an output format and even the oldest IRST systems in 1960s had video output for the pilot. It basically just shows heat sources as blobs like C scope display in older radars. Gums can probably give better explanation having actually operated such IRST systems in F-102 IIRC.

Here is what the IRST display looked like in F-8:

Image

I'm sure OLS-35 is better system, but it seems like it's not an imaging system. Of course having - helps in good conditions to identify targets, but it has quite serious limitations. Non-imaging IRST system is far inferior to imaging systems in every way. Of course Russia nowadays has thermal imaging systems and could update OLS systems for significantly better performance.

Re: FLIR , IRST in air to air mission

Unread postPosted: 12 Sep 2018, 10:30
by falcon.16
Thanks for you resquest, i understand now.

The Russian thermal imaging system that they have now it seems is a copy of Thales-Catherine, but i think it will be a degraded system compare with the original...What do you think?

http://mil.today/2017/Weapons52/

Re: FLIR , IRST in air to air mission

Unread postPosted: 12 Sep 2018, 23:22
by falcon.16
Thanks, now i understand better.

The FSO from Rafale seems a similar system, because it has a tv daylight beside IRST cone. Or i am wrong?

Re: FLIR , IRST in air to air mission

Unread postPosted: 13 Sep 2018, 06:35
by hornetfinn
falcon.16 wrote:Thanks, now i understand better.

The FSO from Rafale seems a similar system, because it has a tv daylight beside IRST cone. Or i am wrong?


It's similar in that sense. AFAIK, the original FSO had pretty poor resolution IR sensor and some variants didn't even have it. - had far better resolution and was thus superior for ID. Latest IR sensors have pretty good resolution and thus - is not necessary, although it still has some benefits. Most important is ability to see colours which might be useful in some situations. That's why many targeting pods also have -.

Re: FLIR , IRST in air to air mission

Unread postPosted: 13 Sep 2018, 10:14
by aasm
hornetfinn wrote:Some basic things about IR sensors:

Sensitivity. Basically sensitivity tells us how weak signals (how little infrared radiation or how cold target is) can be detected. Since IR radiation travels one-way only, sensitivity affects range similarly to RWR or ESM systems (square root). Basically having four times more sensitive IR sensors gives twice the range in the same conditions. Nine times more sensitive sensor gives three times the range. Modern staring cooled sensors usually have sensitivity (NETD) of 10 to 25 mK. Scanned sensors have had sensitivity of about 100 to several hundred mK, basically about an order of magnitude higher. This is because scanning system has a lot less time to handle a single pixel (integration time which is somewhat similar to shutter speed in regular cameras) compared to staring system. So staring sensors can have 2-3 times longer range than scanned sensors.

IR bands. There are basically SWIR, MWIR and LWIR bands (short, medium and long wave). Each of these bands have their own pros and cons. MWIR is usually used in FLIR systems as it offers best overall performance in many conditions (like clear weather, hot and humid conditions). It offers much better resolution than LWIR using similar technology and is much more sensitive to temperatures that vehicles and aircraft emit. LWIR works better for cold targets against cold background and LWIR also penetrates certain weather conditions better (rain, heavy fog, clouds). However these are usually offset by MWIR sensor higher sensitivity against intended targets of IRST systems. SWIR is not usually used as it's not emitted but rather reflected. So it need some source of SWIR light for sensor to work. These sources are the same as visible light (stars, sun, moon, active illumination with laser/lamps). SWIR is also easily absorbed and scattered and usually has nowhere as long range as MWIR or LWIR systems.

QWIP. QWIP is good solution for many applications, but main problem is very long integration time required to have similar detection performance to InSb or HgCdTe sensors. This means they have to give either frame rate or sensitivity to achieve otherwise similar performance. This is why most high-end military applications don't use QWIP technology, although it seems otherwise good.


About DDM NG, Jupiter captor (MWIR) has a sensitivity of 19 mK

http://www.sofradir.com/product/jupiter-mw/

Re: FLIR , IRST in air to air mission

Unread postPosted: 13 Sep 2018, 10:47
by falcon.16
hornetfinn wrote:
falcon.16 wrote:Thanks, now i understand better.

The FSO from Rafale seems a similar system, because it has a tv daylight beside IRST cone. Or i am wrong?


It's similar in that sense. AFAIK, the original FSO had pretty poor resolution IR sensor and some variants didn't even have it. - had far better resolution and was thus superior for ID. Latest IR sensors have pretty good resolution and thus - is not necessary, although it still has some benefits. Most important is ability to see colours which might be useful in some situations. That's why many targeting pods also have -.


Ok.

I understand tv beside IR sensor in FSO is good for help to identify in good conditions. But i see big problem on night. It could detect with Irst, but i do not see way for identify the object, and in web page of the brand, they tells can make identifications day and night.

I do not know how is posible on night without imaging thermal sensor.

Re: FLIR , IRST in air to air mission

Unread postPosted: 13 Sep 2018, 11:27
by hornetfinn
falcon.16 wrote:
hornetfinn wrote:
falcon.16 wrote:Thanks, now i understand better.

The FSO from Rafale seems a similar system, because it has a tv daylight beside IRST cone. Or i am wrong?


It's similar in that sense. AFAIK, the original FSO had pretty poor resolution IR sensor and some variants didn't even have it. - had far better resolution and was thus superior for ID. Latest IR sensors have pretty good resolution and thus - is not necessary, although it still has some benefits. Most important is ability to see colours which might be useful in some situations. That's why many targeting pods also have -.


Ok.

I understand tv beside IR sensor in FSO is good for help to identify in good conditions. But i see big problem on night. It could detect with Irst, but i do not see way for identify the object, and in web page of the brand, they tells can make identifications day and night.

I do not know how is posible on night without imaging thermal sensor.


If you are referring to OLS-35 brochure, I don't think there is a claim that it can make identifications day and night. Just that it works in day and night, which would be true even with non-imaging sensor. Su-35 brochures also say that "It is intended for searching and tracking of aerial and ground targets through their thermal radiation".

FSO in Rafale has thermal imaging sensor and can identify targets day and night. This is what is seen by FSO IR channel:

Image

As can be seen, the resolution is not the greatest for ID which is the reason for having - also for better resolution in daytime. - is definitely useful in OLS-35 also.

Re: FLIR , IRST in air to air mission

Unread postPosted: 13 Sep 2018, 12:48
by falcon.16
hornetfinn wrote:
If you are referring to OLS-35 brochure, I don't think there is a claim that it can make identifications day and night. Just that it works in day and night, which would be true even with non-imaging sensor. Su-35 brochures also say that "It is intended for searching and tracking of aerial and ground targets through their thermal radiation".

FSO in Rafale has thermal imaging sensor and can identify targets day and night. This is what is seen by FSO IR channel:

Image

As can be seen, the resolution is not the greatest for ID which is the reason for having - also for better resolution in daytime. - is definitely useful in OLS-35 also.



Ok i understand, FSO IR cone bring sensor imaging infrared. I read only in one not official website in french language this, but in website official i did not see, for this i had doubts. But really i think tv module beside IR is not relevant but as you tells help.

Thanks.

Re: FLIR , IRST in air to air mission

Unread postPosted: 14 Sep 2018, 06:53
by hornetfinn
I think they went with TV system in Rafale because the IR channel had pretty poor resolution and was best used for searching for targets. TV system had superior resolution and it was also easier to design good long-range optics for it. For example Eurofighter and later F-35 didn't get TV system because they had significantly better resolution in their IR sensor. Their IR system is good enough for long range ID day or night, especially in F-35 with newer detector technology. I think this is why there is a - in OLS-35. AFAIK, Rafale is planned to get new IR system in the F4 standard but it will still be more of a search sensor due to wide FoV optics in IR system. TV system is retained for long range ID purposes. Of course upgraded IR detector would allow longer range ID in conditions where TV system is not effective.

Interesting that "TVchannel" (with space between) seems to get edited by the system. What could be the reason for that?

Re: FLIR , IRST in air to air mission

Unread postPosted: 14 Sep 2018, 17:46
by aasm
The FLIR was subject to extreme heat constraints in a very small volume. Therefore it quickly became too expensive. The second batch of OSF (OSF IT) was deprived of IR channel (but had a more powerful -), awaiting for new captors needing less cooling. It is worth noting that, soon after signature of indian contract, Thales hired a lead engineer fo OSF, mentioning the name of the future OSF, OSF IR, and that the job description clearly mentioned the IR channel. In the meanwhile, MiCA seekers are performing sort of an IRS function.

DDM NG captor, sofradir jupiter, advertise a sensibility of 19mK

Re: FLIR , IRST in air to air mission

Unread postPosted: 14 Sep 2018, 18:27
by falcon.16
hornetfinn wrote:I think they went with TV system in Rafale because the IR channel had pretty poor resolution and was best used for searching for targets. TV system had superior resolution and it was also easier to design good long-range optics for it. For example Eurofighter and later F-35 didn't get TV system because they had significantly better resolution in their IR sensor. Their IR system is good enough for long range ID day or night, especially in F-35 with newer detector technology. I think this is why there is a - in OLS-35. AFAIK, Rafale is planned to get new IR system in the F4 standard but it will still be more of a search sensor due to wide FoV optics in IR system. TV system is retained for long range ID purposes. Of course upgraded IR detector would allow longer range ID in conditions where TV system is not effective.

Interesting that "TVchannel" (with space between) seems to get edited by the system. What could be the reason for that?


Thanks again, now i understand it better.

And i asked because i tried find good information in official websites but companies only write basical information, so it is imposible to know exactly how works the systems and how much good they are or not.

I read DAS system on F-35 will get a big upgrade from Raytheon, and they promise duplicate features. Really could to tell will be a very big jump forward.

Yes i saw on your posts many "-" but i understood it was tv...

Re: FLIR , IRST in air to air mission

Unread postPosted: 14 Sep 2018, 23:10
by ricnunes
hornetfinn wrote:FSO in Rafale has thermal imaging sensor and can identify targets day and night. This is what is seen by FSO IR channel:

Image

As can be seen, the resolution is not the greatest for ID which is the reason for having - also for better resolution in daytime. - is definitely useful in OLS-35 also.



Hi hornetfinn, are you sure that's an IR image and not a TV one?

I'm asking this because (and of course I could be wrong) that image personally seems to be a TV image an not IR one. For example shadows seem to be clearly seen on the image (I don't think that shadows can be seen on IR images, right?) while on the same image it can be seen on the Rafale located below seems to have at least a two color paint scheme (another thing that I also don't think that IR images can show).
I believe that the "low quality" of the picture is due to being a frame screenshot of the recorded (which if I'm not mistaken, usually has a lower quality than the actual imagery) and perhaps even the original TV imagery doesn't have a "very good" quality but here I digress.

Re: FLIR , IRST in air to air mission

Unread postPosted: 15 Sep 2018, 14:07
by aasm
The lower plane is a Mirage 2000. Two tone scheme (air defense)

Re: FLIR , IRST in air to air mission

Unread postPosted: 15 Sep 2018, 18:11
by ricnunes
aasm wrote:The lower plane is a Mirage 2000. Two tone scheme (air defense)


Yes, it's quite possible that you're right.

At first look, they seemed to be the same type of aircraft (Rafales) due to some optic illusion and of course both aircraft having considerable resemblances (even more in images that don't have a very good quality).
But taking a second look, yes I tend to agree with you that the lower plane is likely a Mirage 2000.

Re: FLIR , IRST in air to air mission

Unread postPosted: 04 Oct 2018, 09:35
by hornetfinn
ricnunes wrote:Hi hornetfinn, are you sure that's an IR image and not a TV one?

I'm asking this because (and of course I could be wrong) that image personally seems to be a TV image an not IR one. For example shadows seem to be clearly seen on the image (I don't think that shadows can be seen on IR images, right?) while on the same image it can be seen on the Rafale located below seems to have at least a two color paint scheme (another thing that I also don't think that IR images can show).
I believe that the "low quality" of the picture is due to being a frame screenshot of the recorded (which if I'm not mistaken, usually has a lower quality than the actual imagery) and perhaps even the original TV imagery doesn't have a "very good" quality but here I digress.


Sorry, I missed your question here earlier. Thales site itself claims it's FSO infrared image:
https://www.thalesgroup.com/it/search-m ... search=FSO

Of course it could be an error but it's also sometimes really difficult to tell image from thermal imaging system and monochrome TV system. It depends how the TI system is set up and configured. For example the used wavelength and what temperature range it operates affects the image qualities a lot. Naturally system resolution, sensitivity and image processing does as well. There are number of other things that affect the image quality and appearance, so it can be deceiving. This particular picture can well be from either the IIR or TV system. Thales site says it's IR image, but of course that might be an error as well.

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 04:46
by glennwhitten
If it was an IR image, wouldn't you see a big heat plume out the back, like you do on the EODAS image above.

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 07:05
by hornetfinn
glennwhitten wrote:If it was an IR image, wouldn't you see a big heat plume out the back, like you do on the EODAS image above.


No, not necessarily. That depends on thermal imaging system properties (like type of detector and used wavelength) and how it was configured. For example LWIR system can easily be set up so that only the aircraft itself is visible and not the heat plume. EO DAS uses MWIR detector which is most receptive to higher temperatures and so the heat plume is very visible.

Take a look at here: http://www.dtic.mil/dtic/tr/fulltext/u2/a566304.pdf

Figure 13 in page 18 tells what aircraft components are dominant in each IR band. In MWIR it's the hot parts and plume. In LWIR it's the aircraft body itself. This is due to blackbody physics in each wavelength. That document is very relevant to this discussion in many ways and I'd definitely recommend reading it.

I'm pretty sure that FSO IR channel is LWIR as that gives best performance for long range detection at high altitudes given the likely technology used. EO DAS and EOTS use MWIR as that's superior in all other ways (like ID, targeting and so forth). In FSO - is used for ID.

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 11:01
by falcon.16
hornetfinn wrote:
glennwhitten wrote:If it was an IR image, wouldn't you see a big heat plume out the back, like you do on the EODAS image above.


No, not necessarily. That depends on thermal imaging system properties (like type of detector and used wavelength) and how it was configured. For example LWIR system can easily be set up so that only the aircraft itself is visible and not the heat plume. EO DAS uses MWIR detector which is most receptive to higher temperatures and so the heat plume is very visible.

Take a look at here: http://www.dtic.mil/dtic/tr/fulltext/u2/a566304.pdf

Figure 13 in page 18 tells what aircraft components are dominant in each IR band. In MWIR it's the hot parts and plume. In LWIR it's the aircraft body itself. This is due to blackbody physics in each wavelength. That document is very relevant to this discussion in many ways and I'd definitely recommend reading it.

I'm pretty sure that FSO IR channel is LWIR as that gives best performance for long range detection at high altitudes given the likely technology used. EO DAS and EOTS use MWIR as that's superior in all other ways (like ID, targeting and so forth). In FSO - is used for ID.


Good article.

I have a question; Missiles with IIR are harder to fool using countermeasures as flares. Missiles bring IIR inside its cone, but how does it know which is the heat source they need attack? are they using a database or some similar?

Because if a flare is a very hot source than plume of the engines, the most normal mssiles will go to the flares...it does not matter if it has IIR...

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 11:14
by popcorn
It forms an image and can target.a specific section of said image.

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 13:23
by hornetfinn
falcon.16 wrote:I have a question; Missiles with IIR are harder to fool using countermeasures as flares. Missiles bring IIR inside its cone, but how does it know which is the heat source they need attack? are they using a database or some similar?

Because if a flare is a very hot source than plume of the engines, the most normal mssiles will go to the flares...it does not matter if it has IIR...


IIR missiles have imaging seeker which means they see the image of the target aircraft (or other platform) and also the flares. At longer ranges it can not differentiate between them, but that doesn't matter as target and flares are so close to each other in any case. When it gets closer, it sees them in detail and it can pretty easily tell flares from aircraft as they have totally different visual (in IR though) shape. IIR seekers are not confused by hotter objects as they are not heat seekers (like older IR missile seekers). They are imaging systems operating in thermal wavelengths. For them higher temperature is bit like brighter color.

Flares will have very little effect on IIR seekers unless they can almost totally mask the target aircraft from seeker. IMO, this is why latest flare dispensers dispense a lot of flares to make things difficult even for IIR seekers to handle.

Re: FLIR , IRST in air to air mission

Unread postPosted: 05 Oct 2018, 20:36
by ricnunes
hornetfinn wrote:Sorry, I missed your question here earlier. Thales site itself claims it's FSO infrared image:
https://www.thalesgroup.com/it/search-m ... search=FSO

Of course it could be an error but it's also sometimes really difficult to tell image from thermal imaging system and monochrome TV system. It depends how the TI system is set up and configured. For example the used wavelength and what temperature range it operates affects the image qualities a lot. Naturally system resolution, sensitivity and image processing does as well. There are number of other things that affect the image quality and appearance, so it can be deceiving. This particular picture can well be from either the IIR or TV system. Thales site says it's IR image, but of course that might be an error as well.


No problem hornetfinn.

Yes, I understand that some of the newer IIR imagery has some very , very good definition which makes them very well suitable to perform ID.
However there are still quite noticeable differences between a very good IIR imagery and an even a "not so good" TV (light spectrum) imagery.

For example and looking at the F-35 EODAS video that lrrpf52 posted and while (according to his post) some paint scheme differences could be noted on IIR imagery (like the 'ED' letters on the F-16), these differences are very subtle and (judging by the video) they apparently can be seen or better observed while the "motif" (object) is at a very close range, this by actually being close to the sensor or by being on a "zoomed-in" image and at longer ranges these differences don't seem to be that noticeable at all.
This contrasts with the big differences of coloring seen on that Rafale FSO image (and the "motifs" are not that "close"), namely on the aircraft below (Mirage 2000) which is what I would expect to see on a light spectrum imagery (TV).

Moreover, if that Rafale FSO image would be IIR than we would see a major difference on the engine area in which if the image was "Black-Hot" (IMO the only possibility for that image to be IIR) than we would see a major black coloring, this again in the engine area. This again is not the case and specially notice again, the lower aircraft (Mirage 2000).

Another difference that I notice between a very good IIR imagery and any TV imagery is the edges of an object. Even in very good IIR imagery (like the F-35 EODAS) the object edges always seem to be kind of a "bit rough" or to be more precise quite "pixelated" which contrasts with TV imagery. The aircraft edges on that Rafale FSO image seem IMO to be much closer to what I would expect to see in TV imagery as opposed to IIR.

So yes, I inclined to agree that this is probably a caption error by Thales.

Re: FLIR , IRST in air to air mission

Unread postPosted: 08 Oct 2018, 13:25
by hornetfinn
ricnunes wrote:
hornetfinn wrote:Sorry, I missed your question here earlier. Thales site itself claims it's FSO infrared image:
https://www.thalesgroup.com/it/search-m ... search=FSO

Of course it could be an error but it's also sometimes really difficult to tell image from thermal imaging system and monochrome TV system. It depends how the TI system is set up and configured. For example the used wavelength and what temperature range it operates affects the image qualities a lot. Naturally system resolution, sensitivity and image processing does as well. There are number of other things that affect the image quality and appearance, so it can be deceiving. This particular picture can well be from either the IIR or TV system. Thales site says it's IR image, but of course that might be an error as well.


No problem hornetfinn.

Yes, I understand that some of the newer IIR imagery has some very , very good definition which makes them very well suitable to perform ID.
However there are still quite noticeable differences between a very good IIR imagery and an even a "not so good" TV (light spectrum) imagery.

For example and looking at the F-35 EODAS video that lrrpf52 posted and while (according to his post) some paint scheme differences could be noted on IIR imagery (like the 'ED' letters on the F-16), these differences are very subtle and (judging by the video) they apparently can be seen or better observed while the "motif" (object) is at a very close range, this by actually being close to the sensor or by being on a "zoomed-in" image and at longer ranges these differences don't seem to be that noticeable at all.
This contrasts with the big differences of coloring seen on that Rafale FSO image (and the "motifs" are not that "close"), namely on the aircraft below (Mirage 2000) which is what I would expect to see on a light spectrum imagery (TV).

Moreover, if that Rafale FSO image would be IIR than we would see a major difference on the engine area in which if the image was "Black-Hot" (IMO the only possibility for that image to be IIR) than we would see a major black coloring, this again in the engine area. This again is not the case and specially notice again, the lower aircraft (Mirage 2000).

Another difference that I notice between a very good IIR imagery and any TV imagery is the edges of an object. Even in very good IIR imagery (like the F-35 EODAS) the object edges always seem to be kind of a "bit rough" or to be more precise quite "pixelated" which contrasts with TV imagery. The aircraft edges on that Rafale FSO image seem IMO to be much closer to what I would expect to see in TV imagery as opposed to IIR.

So yes, I inclined to agree that this is probably a caption error by Thales.


With EODAS and EOTS we are talking about MWIR detectors and that gives quite different imagery from LWIR detectors (which FSO IR channel very likely uses). You can not really compare the images of different wavelengths directly. MWIR cameras have peak emission at relatively high temperatures and therefore the it can be better for the detection of jet exhaust or jet plume signatures with high thermal contrast against ambient temperatures. LWIR on the other hand has the peak emissions at approximately room temperature which means it can detect colder objects better especially against cold sky background. On the other hand it's far less sensitive to high temperatures (without special filters) and cuts off at fairly low temperatures. An object which has the surface temperature of 70 degrees Celsius and another with 700 degrees Celsius can look as equally hot in LWIR as it can for example measure temperature range between 0 and 50 degrees Celsius. This means a jet exhaust and jet wing can have equal signature in LWIR while having very large difference in MWIR. In MWIR the 70 degree C object would look like cold object and 700 degrees C object as very hot and bright object.

I do agree however that it might well be caption error by Thales. But at the same time I've seen imagery from thermal imagery which is very close to that image. Also imagery from older systems is usually far less pixelated as they are read and displayed using analog signals instead of digital interfaces. We have to remember than both FSO and Pirate in Eurofighter were developed during 1990s and their technology is pretty old by now.

For example Pirate IRST in Eurofighter does have only IR channel and it seems to give rather similar images like that F-4 in the datasheet:
http://www.leonardocompany.com/document ... nload_file

Engine area is not any brighter than the rest of the aircraft here either.

Re: FLIR , IRST in air to air mission

Unread postPosted: 08 Oct 2018, 17:39
by falcon.16
Yes, its possible to see differente colour on engines/tail and airframe on the phantom image.

Re: FLIR , IRST in air to air mission

Unread postPosted: 08 Oct 2018, 20:50
by ricnunes
@hornetfinn,

Thanks for your reply.
And also thanks for the link (regarding PIRATE).

Re: FLIR , IRST in air to air mission

Unread postPosted: 08 Oct 2018, 22:23
by viper12
Just to add something about toveri hornetfinn's peak emission pertaining LWIR vs MWIR, it's pretty easy to compute the wavelength, assuming aircraft behave more or less like black bodies : https://en.wikipedia.org/wiki/Black-bod ... cement_law

If some aircraft edges were at 100°C = 373K for example, you'd get the wavelength for peak emission at 7.77 microns, which would be near the border between MWIR and LWIR at 8 microns : https://en.wikipedia.org/wiki/Infrared# ... e_infrared

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 06:24
by castlebravo
viper12 wrote:If some aircraft edges were at 100°C = 373K for example, you'd get the wavelength for peak emission at 7.77 microns, which would be near the border between MWIR and LWIR at 8 microns : https://en.wikipedia.org/wiki/Infrared# ... e_infrared


Yes, but a hotter 200° C part of the jet will still emit more intense LWIR radiation than the 100° C area. The peak wavelength gets shorter as temp goes up, but the longer wavelengths are still gaining intensity.

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 08:47
by hornetfinn
ricnunes wrote:@hornetfinn,

Thanks for your reply.
And also thanks for the link (regarding PIRATE).


No problem, hope I can help. Here is another picture which shows the difference in MWIR and LWIR as they took the image at the same time:
Image

For example the jet exhaust plume of that passanger jet is clearly visible in MWIR and not much is seen in LWIR. Of course there are differences even within each infrared band and different systems using different technologies (like detector materials, imaging methods, cooled/uncooled, optics, signal processing, optical filters).

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 10:58
by aasm
Dunno if useful (on topic), but its worth remindin that there are presently two "plug and play" versions of OSF (OSG and OSF IT). The former has IR channel and was organized like that :

Image

The former, FSO IT is devoid of IR channel. The heat constraints on first models were found to be too high in a such a small volume. The IR IRS part being done by MICA IR sensors and eventually damocles pod. (T of IRST part being performed by - and /or damocles pod)

Presently Thales is working on FSO IR (linked to Indian market), with a brand new IR channel called OSF-IR.

All in all the most modern in Europe presently shold be skyward, as pirate (i think, i should check maybe) and OSF will have upgrades within few years.

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 11:59
by hornetfinn
castlebravo wrote:
viper12 wrote:If some aircraft edges were at 100°C = 373K for example, you'd get the wavelength for peak emission at 7.77 microns, which would be near the border between MWIR and LWIR at 8 microns : https://en.wikipedia.org/wiki/Infrared# ... e_infrared


Yes, but a hotter 200° C part of the jet will still emit more intense LWIR radiation than the 100° C area. The peak wavelength gets shorter as temp goes up, but the longer wavelengths are still gaining intensity.


True, but the detector has can only handle finite amount of radiation before they are "filled" (saturated) and this is fairly low in LWIR case. This means that 200° C object usually looks pretty much the same as 100° C object. Of course it's possible to have higher temperature range in LWIR cameras, but that makes them less sensitive which is bad for long range detection.

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 13:35
by ricnunes
hornetfinn wrote:
No problem, hope I can help. Here is another picture which shows the difference in MWIR and LWIR as they took the image at the same time:
Image

For example the jet exhaust plume of that passanger jet is clearly visible in MWIR and not much is seen in LWIR. Of course there are differences even within each infrared band and different systems using different technologies (like detector materials, imaging methods, cooled/uncooled, optics, signal processing, optical filters).


Thanks again hornetfinn for the reply and more precisely for that comparison picture.

However and after reading your very insightful posts together with the great pictures that you posted, I'm still (and probably more so) convinced that picture from Thales is TV and nor IR.
I guess that another reason for this is the cloud details. In that picture from Thales, the clouds have a level of detail that I've yet to see on IR cameras/sensors and only observed on TV cameras/sensors.
Moreover it's interesting (and I believe we can all agree here) that in case that Thales picture is actually IR than it could only be LWIR, right?
But it's also interesting by looking at your latest posted picture, that clouds seem to have a far better detail in MWIR compared to LWIR (but sill less than that picture from Thales).

In the meanwhile I found this I believe, interesting site about the FSO which belongs to one of its manufacturers (Safran):
https://www.safran-electronics-defense. ... /optronics

There we can read the following:
The "front sector optronics" (FSO) system is a passive electro-optical sensor developed for the Rafale multirole fighter. Safran Electronics & Defense is responsible for the infrared search & track (IRST) and forward-looking infrared (FLIR) part of the FSO, while Thales provides the daytime video channel and laser rangefinder


So from what I gather, Safran manufactures the IR part of FSO while Thales itself manufactures the TV part (and also the laser rangefinder) of the FSO.
So why would Thales show/advertise the FSO part which is not manufactured by them?

This indeed sound like a caption error. Perhaps they meant something like: "TV image of in-flight aircrafts from FSO system." but perhaps because the FSO is predominantly an IR sensor (IRST) they put Infrared instead of TV (caption error)? :?

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 13:54
by hornetfinn
Ricnunes, I do concur with your points and agree with you that the FSO image in Thales site is most likely TV image. Just wanted to point out some details about imaging infrared systems.

Aasm, thank you for those details about FSO system. I think FSO IR channel will come back when they put modern components inside it with vastly lower power and cooling requirements. Resolution and sensitivity will likely be much better than with the old system.

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 17:47
by ricnunes
hornetfinn wrote:Just wanted to point out some details about imaging infrared systems.


Which again, I appreciate and thank you! I really learned a lot more about IR sensors/cameras (namely the principles behind MWIR and LWIR) due to your posts, so and again thanks :thumb:

Re: FLIR , IRST in air to air mission

Unread postPosted: 09 Oct 2018, 19:09
by sprstdlyscottsmn
I also enjoyed learning a bit more about these systems. hornetfinn is definitely an asset to the boards.

Re: FLIR , IRST in air to air mission

Unread postPosted: 10 Oct 2018, 08:21
by hornetfinn
Thank you ricnunes and Spurts! I really like the fact that here matters are discussed and argued in very respectful and professional matter. I like being questioned and challenged and learn something myself in the process. :D

Re: FLIR , IRST in air to air mission

Unread postPosted: 10 Oct 2018, 13:24
by aasm
Thank you hornetfinn. About OSF, there was a job offer at Thales about two years ago for ISF IR mentioning both IR channel and India.

Re: FLIR , IRST in air to air mission

Unread postPosted: 11 Oct 2018, 10:13
by aasm
Interesto,g diagram about neaer IR and its use vs vegetation (green curve). See inversion in near IR

Image