Lens for SWIR camera

[sam1275]

Hello everybody, I want to find a lens for a Indigo systems 412-0004-07 SWIR camera which works at a wavelength range up to 1700nm, but there's no manual for it all over the internet, so I don't even know the mount type and the sensor size, will normal NIR CCTV lens also transparent to SWIR? Thank you.

[helius]

will normal NIR CCTV lens also transparent to SWIR? Thank you.

In general, no. Most ordinary glass camera lenses are transparent to Near IR, but not longer waves (SWIR is longer than typical 700-850nm Near IR). You need a lens made from chalcogenide glass, which are made specifically for this purpose.

You should check to see if the mount matches, but C-Mount is typical for this type of camera. It is a threaded mount with an I.D. of 1 inch.

[Someone]

will normal NIR CCTV lens also transparent to SWIR? Thank you.

In general, no. Most ordinary glass camera lenses are transparent to Near IR, but not longer waves (SWIR is longer than typical 700-850nm Near IR). You need a lens made from chalcogenide glass, which are made specifically for this purpose.

You should check to see if the mount matches, but C-Mount is typical for this type of camera. It is a threaded mount with an I.D. of 1 inch.

I've measured some consumer SLR lenses and they can have appreciable transmission out into the 1100-2500nm region, anywhere up to 20%. So their usefulness depends on how much light you have to waste.

[miguelvp]

This link might help

http://www.edmundoptics.com/technical-resources-center/optics/the-correct-material-for-infrared-applications

[sam1275]

Thank you every one for help, it seems normal lens is not good for a SWIR camera, so where can I buy a dedicated SWIR lens? I can't find any on ebay.

[LaserSteve]

It's a controlled item in trade. You would be hard pressed to find a corrected
Multi_element mid Ir lens on Fleabay. Learn to live with a single element Quartz or Sapphire lens and a home made mount.

Steve

[Wim_L]

They're available, for example: http://www.edmundoptics.com/imaging/imaging-lenses/fixed-focal-length-lenses/swir-fixed-focal-length-imaging-lenses/3444

Not cheap, but then again these aren't manufactured in the same volumes as visible light camera lenses.

Oh, and a normal visible light camera lens with the proper mount will, most likely, sort of work in your system. But the antireflection coatings will not be optimised for NIR (so the image will be a bit dim and there may be stray reflections inside the lens) and the lens will not be aberration-corrected for your wavelength range (image quality will suffer, especially towards the edges of the image).

Then, lens mount type. Very likely to be C-mount. It could also be CS-mount, which would limit the lens selection considerably, but CS-mount isn't used that often. Easy to tell the difference, the flange focal distance is different (measure how deep the sensor sits inside the camera... But being very careful not to damage the sensor). Thread specifications can be found scattered all over the web, this may be a good starting point: https://www.schneideroptics.com/info/faq/industrial.htm

[sam1275]

Thank you every one, I think the problem is mostly solved. I may have to find a used lens somewhere, the new ones are too expensive and the FOV is not wide enough.