IR transmission and reception problem

[anboli]

hi to everyone,

im trying to detect the object with the IR Tx and Rx.

its working properly, but my problem is, im not using any lens in front of the Receiver, so that while im showing to the sun light its getting problem, its detecting for the shadow in the line.

my question is whether i need to put the lens before the receiver? and i saw all the sensor in market, all of them have used the lens and protect with the black colored material, my sensor is covered with White covered.

anybody give the suggestion what lens i need to use in Transmitter and receiver?



thanks in advance.

 

[FvM]

The circuit doesn't seem to make sense. Why you are using an optocoupler? Obviously there's no isolation problem.

The circuit however suggests that the problem is about an unmodulated IR "beam". It will in fact suffer from ambient light, direct sunlight is the worst case. Optics is most likely required to make it work. Most optical transmission or light barrier systems are using modulated light. It offers better options to suppress ambient light.

 

[jiripolivka]

It is also a good idea to locate the LED and photodiode in short black tube, to reduce ambient light. Good designs use plastic filters passing only the particular IR wavelength.