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I am working on a project to understand how robot localization is effected by light levels. I am wanting to build a circuit which can be mounted on a small robot near the camera and can determine lux levels. I am spec'ing which sensor type to use for this.

I have come across LDRs but by the looks of them, they can only take granular measurements for light a couple feet in front of them. If I am looking to characterize a whole room, what's the best sensor to use?

Thanks

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    \$\begingroup\$ Are you wanting to measure the light level on the sensor itself (and move the sensor around the room), or are you wanting the sensor to measure the light level at some other point in the room by 'looking' at it while the sensor is stationary? \$\endgroup\$ – brhans Oct 17 at 12:34
  • \$\begingroup\$ Great question. The sensor will be mounted on a moving robot and measure the light at some other point (the ceiling). So your first inquiry is correct. \$\endgroup\$ – neerbasu Oct 17 at 12:45
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    \$\begingroup\$ Can you describe this "robot" in more detail? Why do you think its behavior depends on light levels? How do you intend to correlate light levels with robot position? In any case, a light sensor can only react to the light that actually reaches it. How that happens is entirely up to you -- it's called "optics". \$\endgroup\$ – Dave Tweed Oct 17 at 13:06
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    \$\begingroup\$ Re, "LDR...can only take...measurements for light a couple of feet in front of them." That's not how light works. Here's an experiment you can try at home: Build a simple circuit with an LDR and a volt meter, and see if you can tell whether it is outside in full sunlight, or hidden under an opaque box. The Sun is 93 million miles away!! It's like Dave Tweed said: An LDR (or any other sensor) doesn't measure light that's a couple of feet in front or anywhere else in the room. A sensor can only measure the light that actually hits the sensor. \$\endgroup\$ – Solomon Slow Oct 17 at 13:27
  • \$\begingroup\$ When trying to determine the amount of light falling on an object by only measuring the light being reflected by that object onto your sensor you need to already know a lot about the reflectivity of that object. Imagine your object is painted with Vantablack - you'd probably never be able to measure the light falling onto it because you'd never see any of that light reflected off it... \$\endgroup\$ – brhans Oct 17 at 15:00
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Analog "Light Sensors" for cameras have been around for decades.

But for best? you're too late for the low cost $1 Sensors from Panasonic the AMS-302 Light Sensors which are now obsolete. They worked great on 5V to 12V and you set the gain with a load resistor and they take care of UV, IR and optically filter IR silicon response to the centre 530 nm green eye response that gives us a flat RGB response.

Now there are other options for analog and digital at more cost.

Forget about LDR's unless this is a $1 toy with huge tolerances and poor accuracy is ok. Silicon PD's from Sharp/Vishay, on the other hand, are remarkably consistent but low level and need TIA gain.

But you may want to use IR for emitters and detectors for collision sensing. Analog or digital IRDA types or Remote controllers with AGC to bounce keycodes to avoid error detection. --- For currency, they use UV LEDs, and colors.

Go here for options.

https://www.newark.com/sensor-optical-light-sensor-technology?ICID=I-CT-TP-BROWSE-5

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