The monolithic integration of vertical-cavity surface-emitting lasers (VCSELs) with positive-intrinsic-negative (PIN) photodiodes can be used to dynamically monitor the laser output. If this device is placed in close proximity to a periodic optical grating, and then translated along the axis of the grating’s periodicity, the output of the detector becomes a function of its position relative to the grating. By calculating the frequency of this output as it is moved, the speed of the translation can be determined using the grating period. In addition the distance translated can also be calculated. Therefore the VCSEL/PIN detector and the grating can be used as a position sensor, one that is small and low power but has high sensitivity.
Devices have been successfully created and the goal of this project is to get accurate and repeatable results using a high precision translation stage.
Position Sensing Configuration
VCSEL Surrounded by Detectors