Re: Lock-in puzzle

Roby wrote:
opticalsmile@xxxxxxxxx wrote:


I used a chopper to modulate laser in order to test the Lock-in
ampfier.
In dark room, I curiously switch on flashlight directly to bumping
directly on the photodetector.
In theory of principle of lock-in detection, I should expect that the
display value would not change even under the flashlight illumination.
But I found the value of the Lock-in amp display "decreasing" under
the noise interruption (flashlight).

Why decreasing?

Frank

Perhaps your flashlight driving the detector into saturation?

If not the detector then the electronics following the detector.
I hope the detector wasn't a GaAs photomultiplier.
.

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