Viewing IR radiation with cell phone cameras

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Discussion Overview

The discussion centers around the ability of cell phone cameras to detect infrared (IR) radiation, particularly in the context of testing IR remote controllers. Participants explore the mechanisms behind this phenomenon, including the properties of camera sensors and the effects of IR filters.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that cell phone cameras can register signals from IR LEDs, questioning how this is possible given that IR is lower energy than visible light.
  • Another participant explains that silicon sensors in cameras are sensitive to infrared light around 890nm, but they typically have an IR block filter that prevents most IR light from being detected.
  • A similar point is reiterated regarding the sensitivity of silicon and the presence of an IR block filter, with an emphasis on the brightness of IR LEDs allowing some light to leak through.
  • One participant mentions the historical context of IR filtration in cameras, suggesting it was introduced to prevent the capture of certain details, such as the outlines of warm bodies through clothing.
  • Another participant expresses confusion about the materials used in camera sensors, suggesting that gallium semiconductors are tuned to specific wavelengths and questioning the clarity of IR detection.

Areas of Agreement / Disagreement

Participants express differing views on the materials and mechanisms involved in IR detection by camera sensors. There is no consensus on the specifics of how IR sensitivity is achieved or the implications of the technology.

Contextual Notes

Some claims about the specific wavelengths and materials used in camera sensors remain unresolved, and there are differing opinions on the effectiveness of IR detection in various camera models.

hagopbul
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TL;DR
trying to understand how ir radiation from a remote controller is detectable by cellphone camera
Hello All:

i saw some youtube videos on testing IR controllers on normal with no add ons Cell phone camera and the cell phone screen is showing signal emitted by the IR LED of the remote controller , how the cell phone camera sensor are able to register a signal from an IR LED , the pixle in the sensor is semiconductor with a band gab corresponding for a color the IR is lower energy than most of the colors in the white light and the intensity of this IR LED is not even considered enough for any thing

i test it by my self with low power IR LED from an 5 year old remote of air conditioner and the screen of the cell phone registered or better say showed the detector blinking which i didnt understand due to the reasons i mentioned above

https://www.carolina.com/knowledge/2020/02/20/make-the-invisible-visible

Best
H.B.
 
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The detectors on the camera are all the same silicon with color filters. Silicon is most sensitive in the infrared (around 890nm) and so all cameras have an IR block filter also. Some leaks by and the LEDs are quite bright.
 
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hutchphd said:
The detectors on the camera are all the same silicon with color filters. Silicon is most sensitive in the infrared (around 890nm) and so all cameras have an IR block filter also. Some leaks by and the LEDs are quite bright.
One can also quite easily remove the IR filter from many webcam models, to build a IR head tracking system or similar.
 
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A reason for the introduction of IR filtration was the defeating of apparent denudation ##-## prior to then, video cameras could capture specifics (vaguely) of warm bodies through clothes.
 
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For silicone it is 1100 nm or close to that , but I wasn't aware that they use silicone in camera sensor also , I was under the impression that the semiconductor in the sensor is tuned to specific wave length the gallium and other gallium semiconductors are close to 800 nm

Every pixel in camera are composed usually of some sensors tuned for specific wave length

That why the detection of ir wavelength was just not clear
 

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