| 摘要 |
<p>Method and apparatus for obtaining an enhanced clearer measurement signal with improved fringe contrast from a laser interferometer. The interferometer sends a laser beam (12) through atmospheric air to a polarizing or nonpolarizing beamsplitter (13) that sends one laser beam portion (14,16) to a fixed reference retroreflector (15) and another portion (19,21) to a movable measurement retroreflector (20). Both beams, upon retroreflection go back to the beamsplitter and are recombined to produce a combined beam (22) that is then sent to an aperture (30) such that only a small selected portion of that combined beam passes through the aperture, attenuating the energy of the combined beam but increasing its fringe contrast. This portion is sent to a detector (32) and is subsequently amplified by a high-gain amplifier.</p> |
