Light conductive plastic for luminosity sensor mount - Page 1
Forum section: electronics / projects

author: hozone
author_rank: Regular Contributor
timestamp: December 09, 2014, 07:51:08 pm
content: Hello,A quick overview: 1 post here for me, but a follower of Dave and a reader of the forum.Then, my question.I've to mount a light sensor, BH1750 mounted on a board (like the one attached), on my project box.I need some sort of conductive plastic to make the light flow from outside of the box to the BH1750 surface.The light sensor should be mounted next to the case, that way the conductive plastic will be less than 1cm, or even on the underlying main board, that way it will be 4 cm.Any suggestion are welcome.p.s. sorry for my poor english.

author: ajb
author_rank: Super Contributor
timestamp: December 09, 2014, 08:37:46 pm
content: Lightpipes (designed to conduct light from an LED to the outside of an enclosure) are readily available in a wide range of sizes and shapes and would probably do what you want. There are some panel-mount varieties that incorporate a fresnel lens that may help increase the receptive angle of your sensor, if that's important to you. You can also make a rudimentary light pipe from a piece of acrylic rod. You'd probably need to do some experimentation to determine what configuration is most suitable to your application and what physical arrangement gives optimal coupling into your sensor.Note that typical light pipe materials are intended for the visible spectrum, and may not be suitable if you were trying to detect in the infrared or UV ranges.

author: hozone
author_rank: Regular Contributor
timestamp: December 10, 2014, 09:30:40 am
content: Thank you! I will search for lightpipe and also will do test on acrylic.

author: nfmax
author_rank: Super Contributor
timestamp: December 10, 2014, 09:41:55 am
content: What are you planning to do with the measurements of light level? You should be aware that the effectiveness of coupling light from the guide into the photosensor will be very dependent on the relative positions of the two items. If repeatability matters, make sure that the two items cannot move relative to each other

author: hozone
author_rank: Regular Contributor
timestamp: December 10, 2014, 12:36:35 pm
content: It's for a networked ambient monitor.I must do test from 100lux to 2000lux with sensor inside the box, and outside. Light emission at the same angle.I do not expect the same results, but i hope there will be some kind of linear relation between the two measurment. I mean, 500lux using the light pipe, 800lux without using it 1500lux using the pipe, 1800lux without it. That way i could set a 300lux offset. Instead if there is a linear relation, a scale vector.

author: hozone
author_rank: Regular Contributor
timestamp: May 03, 2015, 12:35:01 pm
content: I've finally mount it using a transparent PMMA square piece of plastic, distance from the sensor it is measured using this vishay application note:"Ambient Light Sensors - Circuit and Window Design - vishay"http://www.vishay.com/docs/84154/appnotesensors.pdfAnother interesting application note could be found here:"optical design of ambient light sensor an-32 - Microsemi"http://www.microsemi.com/document-portal/doc_download/14684-an-32-optical-design-of-ambient-light-sensor