THORLABS APD410 Series, Operation Manual

Page: 24 / 30

© 2020 Thorlabs 22
APD410x
5.6 Fiber Coupling onto Small Detector Area
When coupling an optical fiber into the APD410x, please consider the beam divergence out of
the fiber tip and the active detector area.
For detectors with an active area smaller than 1 mm, the beam divergence out of the fiber
needs to be compensated by using a collimator and a focusing lens. Below is a possible ar-
rangement:
The assembly in front of the APD410x comprises of a fiber collimator (dependent on fiber), a
lens tube collimator adapter (AD11F or AD12F, dependent on collimator), a SM1L1 lens tube
with aspheric lens inside (not visible above) and a LM1XY X-Y translation mount.
The beam out of the fiber is collimated (transferred into a nearly parallel beam) and afterwards
focused by the aspheric lens onto the detector. The X-Y translation mount allows the focused
beam to be aligned with the center of the sensor.