Photodiode to DAQ

[pooh1]

Dear folks,

I am trying to measure light intensity using a photodiode (Thorlabs, SM1PD1B). I have PCI-6251 DAQ and BNC-2090A and SCB-68 accesory.

I am trying to connect my bare Si photodiode (Thorlabs, SM1PD1B) to SCB-68 Channel 7 and read a voltage response. 

I wired a photodiode cathode to terminal 57 and an anode to terminal 23 as DIFF mode and also place 100kohm resistor between photodiode anode and termial 23 as discribed in following link.

http://forums.ni.com/ni/board/message?board.id=250&message.id=13207

But I can not get any signal out. I want to use this channel to check a laser signal change during my sample measurements. I have an Thorslab amplifier for another photodioe for my real measurement and can get the voltage signal w/o a problem. But I don't want to buy or build a transimpedence amplifer for this channel. I am not good at this. If I can get any reasonalbe signal from this photodiode w/o an amplifier, I am ok with it. Do anybody know how I can get a voltage signal (0 to 10V or 5V) from this photodiode without an amplifier? Do i really need an amplifer for this measurement???

Thanks in advance. 

[Brian_Beal]

A photodiode is not like a solar cell.  Typically, you need to apply a voltage to the photodiode, and measure the current.  The manufacturer of the photodiode should have some tech notes on how to do that.

[walter-donovan]

Your placement of the resistor is also suspect. Your own wording states you've connected anode to term 23 and resistor between anode and term 23. This can not e right. Do you mean resistor is in series between anode and term 23, i.e. term 23 is not connected directly to anode?

Bias resistor doesn't belong there.  You link to the diode in the catalog has a pdf data sheet, complete with suggested circuit. Why can't you use their circuit?

FWIW You will proably get more response in a hardware based forum rather than Labview.

Message Edited by walter-donovan on 01-16-2009 07:11 AM

[pooh1]

Thanks folks.

I will move my question to signal conditioning forum then.