Ambient Light Sensor Pipe?

Thread Starter

Almir D

Joined Dec 11, 2017
6
Is there a pipe that can be used for an ambient light sensor.
I'm having a problem where my light sensor is about 5mm or more inside of the product with a hole for a light to pass in. Ideally, a light sensor should be on the surface of the unit for maximum light exposure. Is there a light pipe that I could use to pass light to a light sensor?
 

wayneh

Joined Sep 9, 2010
16,229
Fiber optics. You need a short hunk of cable. You could probably find some scrap if you could find somewhere they’ve installed some. But it’s probably available from commercial sources also. A piece of lucite rod would work also.
 

Thread Starter

Almir D

Joined Dec 11, 2017
6
Fiber optics. You need a short hunk of cable. You could probably find some scrap if you could find somewhere they’ve installed some. But it’s probably available from commercial sources also. A piece of lucite rod would work also.
That's kinda what I had in mind, but I'm wondering if there such a thing like a light pipe for a light sensor. I'm looking for something that is manufacturing friendly.
 
Not really sure, I'm gonna have to try and see. These are meant to take a light from an LED (typically light that is narrow angel focused) and pass it on. Not sure if these will be as efficient for a reversed process.
Having worked on a similar problem a while back, using a tiny I2C light sensor to adjust the screen brightness on a portable measurement trolley, the flex lightpipes from Farnell worked well, the offset due to the losses was adjusted in the software, as the sensor would run down to single digit lux levels it was not an issue.
 

Reloadron

Joined Jan 15, 2015
5,104
Since the thread is a few weeks old I would guess the thread starter has a solution by now. Anyway here are a few images of what I would try:

Below is a simple pen light just a cheapie small flashlight using two AA batteries and a few additions. The first is just a rubber boot as used as an insulator on old automotive distributor caps and a 90 degree bent piece of round acrylic rod.
Bore Light 2.png

Once assembled the thing looks like the below image:
Bore Light 4.png

Just a simple cheap piece of acrylic dowel bent 90 degrees and it conducts the light extremely well. Bending is accomplished by just applying a little heat and gently bending the dowel around a piece of pipe or really anything round. The acrylic can be had at just about any home improvement store like Lowes or Home Depot or any hardware store. I have used these things for years inspecting rifle bores as a quick check. The acrylic hardly attenuates the light at all.

Ron
 

Thread Starter

Almir D

Joined Dec 11, 2017
6
I ended up using light pipe very similar to this one https://au.rs-online.com/web/p/led-light-pipes/1699841/
It worked pretty well. Better than I expected at first. I guess the key is that both ends of the pipe are clear, instead of being sanded off/milky looking. I'm using tiny i2c sensor and what I initially have done is to place this sensor 5mm behind the housing with ~5mm hole for the light to enter, covered with a clear plastic as a protection. I compared the results from this setup and light pipe setup, I was pleased to see that I'm getting higher lux readings using the light pipe.
 
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