I am working with a photodiode that is supposed to detect very tiny amount of LED light(the light will be programmed by an attiny 85). Using different kind of lenses I succeeded amplifying the light amount that will fall on the photodiode. Making use of op amps I could bring the photo detector to trigger an action (start a servo motor) as the small light amount was falling on it.
R1: 10M; Opamp: LM358; photodiode: VTB8440BH; Energy consumption should be as minimal as possible.
Now I have the problem as this experiment only works in dark environment. Since the photodiode has become very sensible with the op amp even small amount of daylight is detected by the photodiode. The photodiode I make use of is VTB8440BH (Datasheet Photodiode http://www.farnell.com/datasheets/57158.pdf.) As per datasheet its sensitivity peaks at 500nm. Since the light source is a white/blue LED ( arrnd. 450nm) I have selected this photodiode. However now I learned that even the wavelength of daylight settles btw 350 and 700 nm. Hence I experience the problem as mentioned above that the photodiode cannot differ between both the lights. I am aware to avoid this issue I should/might use an Infrared Light source. I have also learned that I might use a filter to avoid daylight however in my case I doubt (not sure though) that only daylight can be disselected filtering the led light. However I want to do it with an LED. Is there a possibility to avoid daylight and detect white/blue led???
I have already considered interesting discussions however I could not extract the required information for me to address my issue. how to make a system respond to IR laser? Poor man's IR obstacle sensor make sense(improve) from signal under daylight