conversion to colour sensor

hey folks,

i was working with a digital ir proximity sensor(based on lm358) and i had a task to indentify blue colured objects in a i intend to change the ir led with a blue led. is it a viable option?

here more information about the ir sensors

It depends on how sensitive to blue light your photodiode is.
If it is an IR photodiode, the answer may be "not very"

are there any specific photodiodes which are sensetive to visible spectrum(blue part specifically)?