Light sensor being overwhelmed, suggestions?

Other Hardware Sensors
1

I'm currently working on a project that involves light sensing. Specifically detecting when an led blinks from appoximatly 2-5mm away. Only problem is there is a clear case between the led and my sensor and the project will be in outside in nearly direct sunlight. I've reduced the ambient light as much as physically possible but it is still fairly high. i.e.

LED <3mm> Sensor
=D |clear case| D=

My first approach was to use two cds photocells (one facing directly towards the led, and the other offset slightly) and a comparator circuit to detect when the led flashes. That didn't work because the photocells would be "washed out" by the sunlight and could not sense the led. So, I've been searching digikey for a different sensor to suit my needs, one that would be sensitive to the 630nm-ish wavelength of the led but still have range to detect changes in a high lux environment. So far All of the sensors I've tried haven't worked out. Looking through various forums hasn't been much help either, most solutions I've read involve reducing the ambient light in some way. I was wondering if anyone could suggest a sensor that might work or perhaps a different approach that may be successful.

Thank you for any suggestions.

2

You can do several things. Put the sensor at the end of a long tube to cut down on the angle. You can also try coloured filters of the same colour as the LED.
Are you using the analogue input?

3

This is a standard problem with IR LEDs and detectors and is solved there by using a carrier frequency, typically 38kHz
or near, standard ICs are available to encode and decode. The 38kHz carrier puts the signal in a frequency domain
with much less sensitivity to ambient light and enables narrow-band amplification to be employed.

4

shades 8)