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To product page OPM200


What are xInGaAs and V-InGaAs Detectors?

These are two variations on the standard InGaAs (Indium-Gallium-Arsenide) photodiode.
The xInGaAs type has extended IR sensitivity out to 2100nm useful wavelength range. The short wavelength cut-off is the same as standard InGaAs.
The V-InGaAs type has extended visible range sensitivity down to 400nm useful wavelength range. The long wavelength cut-off is the same as standard InGaAs.


What is a “free beam” input receptable?

By “free beam”, we mean that the photodiode is openly mounted on the front plate of the unit. This is to allow measurement of free beams (not fibre coupled). This configuration may be inconvenient since the amplifier must be mounted directly in the beam path. If you wish to have a remote detector head then use the TZA200 (transimpedance amplifier) instead to measure the current from the remote photodiode.


What does an output impedance of 50Ω mean?

The output impedance of an amplifier is an important factor when dealing with fast signals. The speed of the OPM200 is fast enough for this parameter to be relevant. Essentially, the output of the amplifier is a 50Ω resistance in series with the output. This allows you to terminate the signal line with a 50Ω resistance to prevent back reflections. The result is a clean signal transient without overshoot. The disadvantage is that the signal voltage is halved by doing this. The amplifier may be used without the 50Ω termination resistance, but then there will be overshoot when amplifying fast transients.

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