Patent ID: 8724108
Filing Date: 2014-05-13
Classification: G02B

Abstract:
1. A photoelectric autocollimation method based on beam drift compensation that employs a reference mirror or a corner reflector to reflect the reference beam, the method comprising: forming a collimated beam by passing a polarized beam emitted from a laser source through a reticle, a polarization-insensitive beamsplitter and a collimating lens successively; reflecting the collimated beam by a beam steering device into a first polarizing beamsplitter, where the collimated beam is split into a polarized transmitted beam and a polarized reflected beam having polarization states mutually perpendicular to each other; forming a measurement beam by reflecting the polarized transmitted beam by a measurement mirror that carries the two-dimensional angular deflection information of the measurement mirror and the angular beam drift information in the measurement process; transmitting the measurement beam through the first polarizing beamsplitter again and then returning the measurement beam reversely to the polarization-insensitive beamsplitter where the measurement beam is split into a transmitted measurement beam and a reflected measurement beam, the reflected measurement beam being received by a first photoelectric position sensor after it transmits through a second polarizing beamsplitter; transferring the output signal of the first photoelectric position sensor to a data processing controller as a measurement signal; forming a reference beam by reflecting the polarized reflected beam by a reference mirror or corner reflector that carries only the angular beam drift information in the measurement process; reflecting the reference beam by the first polarizing beamsplitter again and returning the reference beam reversely to the polarization-insensitive beamsplitter on a common path with the measurement beam; splitting the reference beam into a reflected reference beam and a transmitted reference beam by the polarization-insensitive beamsplitter, wherein the reflected reference beam is received by a second photoelectric position sensor after it is reflected by the second polarizing beamsplitter; transferring the output signal of the second photoelectric position sensor to the data processing controller as a reference signal; providing a signal to the beam steering device in real-time according to the reference signal that represents the magnitude of beam drift; and deflecting the directions of the measurement and reference beams simultaneously by the beam steering device to the opposite direction of beam drift, while calculating the angular deflection of the measurement mirror that deflects with the object being measured.