Operation - THORLABS APD410 Series Operation Manual

3.3 Operation

· Turn the power switch to I. The green LED on the APD410x indicates correct power sup-
ply.
· Set the Gain knob to its MIN position.
· Adjust the optical source to the optical input. The maximum OUTPUT voltage swing is 4.1
V for high impedance loads (2.0 V into 50 W loads). The output signal must not exceed
this maximum output voltage to avoid saturation. External neutral density filters or attenu-
ators are recommended to reduce the input light level in critical cases.
· The Gain adjustment can be used for setting the output voltage to an appropriate value.
Note
APDs generate noise due to the multiplication process, so excess noise increases as the
gain is increased. Similarly, the photocurrent generated by signal light is also amplified by
the gain. These facts mean that the best S/N exists at a certain gain.
· Turn the power switch to O when you are finished the measurements.
Note
Avoid saturating the amplifier! Therefore, make sure that the optical input power does not ex-
ceed the saturation power level listed in
Attention
Exceeding the optical damage threshold input power will permanently destroy the detector!
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