Laser Heterodyne Interferometric Apparatus and Method Based on Plane Mirror Reflection

A based laser heterodyne interferometric apparatus based on plane mirror reflection, comprising:

• a dual-frequency laser, a first photoelectric receiver, a second photoelectric receiver, a first polarizing beamsplitter, a second polarizing beamsplitter, a third polarizing beamsplitter, a quarter-wave plate, a right angle mirror, an optical compensator, and a measured plane mirror, wherein the first polarizing beamsplitter, the second polarizing beamsplitter, the quarter-wave plate, the third polarizing beamsplitter, and the optical compensator are sequentially arranged in parallel between the dual-frequency laser and the measured plane mirror;
• the first photoelectric receiver is disposed in the reflection direction of the first polarizing beamsplitter;
• the second photoelectric receiver is disposed in the reflection direction of the second polarizing beamsplitter;
• and the right angle mirror is disposed in the reflection direction of the third polarizing beamsplitter);
• wherein one beam of emergent light outputted by the dual-frequency laser is split, after passing through the first polarizing beamsplitter, the quarter-wave plate, and the third polarizing beamsplitter, into reference beam A and measurement beam A;
• the other beam of the emergent light outputted by the dual-frequency laser is split, after passing through the second polarizing beamsplitter, the quarter-wave plate, and the third polarizing beamsplitter, into reference beam B and measurement beam B;
• the reference beam A is diagonally reflected back on the third polarizing beamsplitter by the right angle mirror and is then reflected by the third polarizing beamsplitter, wherein the reflection direction of the reference beam A coincides with the direction of the measurement beam B after the measurement beam B is reflected by the measured plane mirror and transmitted through the optical compensator and the third polarizing beamsplitter, the coinciding two beams of light being reflected on the second photoelectric receiver by the second polarizing beamsplitter;
• and the reference beam B is diagonally reflected on the third polarizing beamsplitter by the right angle mirror and is then reflected by the third polarizing beamsplitter, wherein the reflection direction of the reference beam B coincides with the direction of the measurement beam A after the measurement beam A is reflected by the measured plane mirror and then transmitted through the optical compensator and the third polarizing beamsplitter, the coinciding two beams of light being reflected on the first photoelectric receiver by the first polarizing beamsplitter;
• the measured plane mirror is disposed on a measured object the interferometric apparatus is adjusted to make propagation directions of the emergent beams of the dual-frequency laser parallel to the moving direction of the measured object.