signal from photodiode DET10A to computer

[shiju_ul]

Hello frnds,

I have a photodiode DET10A (thorlabs) and I want to take its output to the computer, so as to process the signal using Labview. I am using USB-6008 as the daq card. However, I am only observing the pixel noise of the DAQ card and no measurement in the Labview. The plot just shows values changing from 1.4 – 1.42 V. This is what it shows even when the PD is not connected. 

Do you think I need to use an amplifier? Is that i  should change the DAQ card?

Please help!!!

thank you very much
with regards
Shiju

[KostasB]

Hi,

What kind of signals does the photodiode emit ( amplitude, frequency)?

KostasB

NIUK Applications Engineering

[DFGray]

The DET10A is essentially a bare photodiode, so you need a transimpedance amplifier to make it work with a DAQ board.  The photodiode is a current mode device (0.45A/W output for this model).  The DAQ board is a voltage mode device.  The transimpedance amp will convert for you and allow you to set the gain so the DAQ board input range is properly utilized.

[shiju_ul]

thank you very much, Kostas!

That was a very pleasing answer. Could you suggest me simple transimpedence amplifier circuit or what should i connect?

thank you once again

[shiju_ul]

Can I take signal from my photodiode DET10A to computer using DAQpad6020E. Can i use CB-68LP as the connecting board?

[Henrik_Volkers]

You can build up a simple transimpedance amp. yourself . Depending on your needs (speed, noise) it just a little peace of breadboard, an opamp and a handfull of discrete Rs & Cs (counting not pouring 😉  )
schematics  can be found in the basic appnotes or circuit collections from Linear , TI , NS   etc .
Basic Fig. 12-10 in   http://focus.ti.com/lit/an/slod006b/slod006b.pdf
But there are many more

[DFGray]

You will need a transimpedance amp to use the DAQpad6020E and CB-68LP.  As Henrik mentioned, they are easy to make if you can't afford a commercial one.

[terry_bell]

If you are making a transimpedance amp, one thing that you have to keep in
mind is board leakage. Most photodiodes have high output impedances, so when
coupled with the high input impedance of the op amp, board leakage can be a
significant source of error. Most designs will use a guard ring which keeps a
ring of common potential around the inverting input on both the top and
bottom of the board. This IS an important element.
😆
tb

[lmtis]

Alternately if you have ~$300 to spend you could order the Thor Labs amplified version of your photodiode (PDA10A).

[Henrik_Volkers]

tb: Good point about the board (layout).  Maybe that's why I misspell piece (of board) ???

My one and only transamp I build was in dead bug technology and I used an ordinary LED as source ...