# WWII era IR Sensor?

**URL:** <https://boards.straightdope.com/t/wwii-era-ir-sensor/494616>\
**Category:** Factual Questions\
**Created:** [April 28, 2009, 2:55pm UTC](https://boards.straightdope.com/t/wwii-era-ir-sensor/494616 "2009-04-28T14:55:09Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\
**Post date:** [April 30, 2009, 1:00pm UTC](https://boards.straightdope.com/t/wwii-era-ir-sensor/494616/21 "2009-04-30T13:00:49Z")

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> [@Paul\_in\_Qatar](#):
>
> Well, I have sent the B-29 to Europe so the B-17s are off to Japan.

How does it come to pass that? I presume that you do not have the world’s largest aircraft carrier, England. 🙂

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [April 30, 2009, 1:19pm UTC](https://boards.straightdope.com/t/wwii-era-ir-sensor/494616/22 "2009-04-30T13:19:15Z")

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> [@](#):
>
> I’m pretty sure glass does not transmit IR very well.

That’s a pretty broad brush to use on a very broad wavelength range. Near Infrared (NIR) goes through glass just fine, and you can use glass lenses to focus it. That;s from the edge of the visible at around 700 nm up to a bit beyond a micron. When you get beyond that you have to start using different materials like semiconductors and evenually Cadmium Sulfide or Selenide, or salt (having worked with coated salt windows – as well as the other substances here – I can swear that it’s a pain in the neck to work with)

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