SELF CALIBRATION FOR MIRROR POSITIONING IN OPTICAL MEMS INTERFEROMETERS

摘要

A Micro-Electro-Mechanical System (MEMS) apparatus provides for self-calibration of mirror positioning of a moveable mirror of an interferometer. At least one mirror in the MEMS apparatus includes a non-planar surface. The moveable mirror is coupled to a MEMS actuator having a variable capacitance. The MEMS apparatus includes a capacitive sensing circuit for determining the capacitance of the MEMS actuator at multiple reference positions of the moveable mirror corresponding to a center burst and one or more secondary bursts of an interferogram produced by the interferometer based on the non-planar surface. A calibration module uses the actuator capacitances at the reference positions to compensate for any drift in the capacitive sensing circuit.

主权项

1. A Micro-Electro-Mechanical System (MEMS) apparatus, comprising:
a MEMS interferometer including:
at least one mirror optically coupled to receive and reflect light and configured to produce an interferogram therefrom, a first mirror of the at least one mirror having a non-planar surface; anda MEMS actuator coupled to a moveable mirror of the at least one mirror to produce a displacement thereof, the MEMS actuator having a variable capacitance; a memory maintaining a table mapping stored capacitances of the MEMS actuator to respective stored positions of the moveable mirror; a capacitive sensing circuit coupled to the MEMS actuator, the capacitive sensing circuit configured to:
sense a first measured capacitance of the MEMS actuator at a first reference position of the moveable mirror corresponding to a center burst of the interferogram produced as a result of movement of the moveable mirror; andsense a second measured capacitance of the MEMS actuator at a second reference position of the moveable mirror corresponding to a secondary burst of the interferogram produced as a result of movement of the moveable mirror and the non-planar surface; and a calibration module configured to use the first measured capacitance at the first reference position and the second measured capacitance at the second reference position to determine a correction amount to be applied to the stored capacitances in the table.