How to determine the signal strength of the IR transmitter
i had designed the through beam sensor by using of the IR transmitter and IR Receiver LED. Its working quite properly. My doubt is how to find the signal strength of the IR tranmsitter Led, without receiver. By the use of receiver i can determine the distance. but not able to find the strength. If i vary the Forward voltage of the IR Transmitter, distance getting increased, while decrease the forward voltage, distance also getting reduced.
Kindly tell me how to determine the strength of the TRANSMITTER?
Thanks in advance,
anboli
Do you mean the peak power of the infra red? Measure the power going into the diode, look up the manufacturers spec. Compensate for any focussing optics and you have your answer.
Frank
You can check the specs of the IR Transmitter LED from the data sheet which will give you some information about its dissipation of IR for along with the distance.this might help you....
in the datasheet they given the wavelength 950nm and degree as +or- 15degree..
http://www.vishay.com/docs/81055/tsus520.pdf
this is the IR transmitter which im using..
Figure 5 and Figure 6 do answer your question.
Fig 5 and 6 give you a relationship for your requirement as indicted by FvM. If you want to calculate the signal strength at some distance from transmitting LED, you can estimated it with radar equation.... but IR is not same as Microwave... IR fades away quicker than microwave