Adding Zooming Capability to my Far Infrared Spectrum Sensor

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rubenhak
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Physics noob here. I have the cheapest FLIR sensor (80x60 px sensor). It captures Longwave infrared, 8 μm to 14 μm. It has a tiny lens (probably 1mm in diameter). Trying to add a zoom ability to this sensor.

I have different DSLR lens and other optical scopes. I tried holding the tiny FLIR camera behind the zoom lens hoping to see the heat of object behind the zoom lens, but it just shows the heat of lens itself. Tried different positions, etc, but didn't work.

What am i doing wrong? Are the consumer lenses absorbing infrared wavelengths?

Some specs here: https://lepton.flir.com/wp-content/uploads/2015/06/lepton-2pt5-datasheet-04195.pdf
 
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rubenhak said:
What am i doing wrong? Are the consumer lenses absorbing infrared wavelengths?

Probably. Optical glass designed for use with visible wavelengths is usually a very poor transmitter of far IR.
 
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rubenhak said:
... FLIR ...
What's wrong with simply 'IR'? Is it fixed to a plane, looking only forward?
 
rubenhak said:
Summary:: Can a consumer lens zoom a far infrared light?

Physics noob here. I have the cheapest FLIR sensor (80x60 px sensor). It captures Longwave infrared, 8 μm to 14 μm. It has a tiny lens (probably 1mm in diameter). Trying to add a zoom ability to this sensor.

I have different DSLR lens and other optical scopes. I tried holding the tiny FLIR camera behind the zoom lens hoping to see the heat of object behind the zoom lens, but it just shows the heat of lens itself. Tried different positions, etc, but didn't work.

What am i doing wrong? Are the consumer lenses absorbing infrared wavelengths?

Some specs here: https://lepton.flir.com/wp-content/uploads/2015/06/lepton-2pt5-datasheet-04195.pdf

Nice camera! Very cool.

IR lenses are typically made of germanium, not glass. I don't think there's a DIY low-cost way to kludge together a zoom (varifocal) lens. Zoom with your feet!
 
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Thanks for help guys!

A.T.> I need a zoom ability. As Andy noted, will just use my feet then!
 
A.T. said:
What's wrong with simply 'IR'? Is it fixed to a plane, looking only forward?
Originally, but now it's a company/ brand name.
 
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Maybe something based on a parabolic reflector? Easier to reflect IR than transmit it.
 
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Germanium lens sounds expensive...

I was hoping to make use of existing components, building a lens from scratch sounds way too complex.
 
Andy Resnick said:
Nice camera! Very cool.

IR lenses are typically made of germanium, not glass. I don't think there's a DIY low-cost way to kludge together a zoom (varifocal) lens. Zoom with your feet!

Sapphire is my go-to glass for transmitting IR. Bonus: it also transmits visible and UV and is extremely scratch resistant. The price, though...
 
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DaveE said:
Maybe something based on a parabolic reflector? Easier to reflect IR than transmit it.
Absolutely. It's not difficult to fabricate a small reflector and to polish it. A spherical mirror would be easy to make by pressing a ball bearing into soft metal. (I imagine this is all very small scale optics.) You can mount a reflector off axis (same technique as satellite receiving dishes). The image on the sensor could be distorted but that's easy to compensate for. The accuracy of the surface is less critical for IR but you can measure the performance with visible light (unlike a dispersive lens). If you want a longer focal length than the camera's lens then focussing could be more critical.
Zoom capability is a relatively new phenomenon and not a necessity. Cinema and TV got on very well by using a few fixed focus lenses on a turret for each camera.

This would only be necessary if "zooming with feet" won't work.
 
rubenhak said:
There seem to be overlap with Germanium, but doesn't seem enough for far infrared imaging.
https://www.edmundoptics.com/knowle...e-correct-material-for-infrared-applications/

That is, of course, true, and I missed the part where you needed far IR. My applications are all MWIR with a need for simultaneous visible transmission.

I do know where you can get NaCl for cheap, but not in a single, optically-clear crystal. :wink: