It is concerning about the better use of laser pointer

It is concerning about the better use of laser pointer
Laser interferometer the overall layout of the instrument optical path a number of possible choices. Generally follow the common path laser interferometer optical path design principles, namely, the measuring beam and reference beam to go down the same path as far as possible in order to avoid measurement errors caused by the atmospheric and environmental conditions on the inconsistency of the two optical path of The typical optical path layout of the common optical path layout using the corner cube reflector, as shown in Figure 6-3. Figure 6-3a in the retroreflector allows the incident and reflected light separated in space a certain distance, this optical path to avoid the reflected beam back to the laser, so as not to return the beam to cause the instability of the laser output frequency and amplitude. The retroreflector anti-yaw and pitch performance, can eliminate the error caused by measuring the mirror deflection. laser pointer conforms to the quality control requirements. 
The signal to pass through the carrier, making the interferometer using AC amplified, isolated from external environmental interference caused by DC level drift. Use this technology to the design of interferometer is called the heterodyne interferometer, or exchange the interferometer. There are two ways to produce the interferometer carrier signal, a participating interfere two beams of light to generate a frequency difference, this two-beam optical coherence of the results to the optical film, converted into electrical signals, the difference frequency carrier, and the other is to directly generate the carrier signal modulation, interference with the light of the measuring arm of the reference beam in the interferometer's reference arm. The former is called optical heterodyne interferometer, while the latter is often called the quasi-heterodyne interferometry.  Complementarity principle, can be a variety of fine metal wire (such as wire, watch springs, etc.) and the size of the ribbon for high-precision non-contact measurement, the results of the same measurement slit. Complementary range of measurement of measurement of diameter is usually 0.01-0.1mm, the measurement accuracy can be achieved 0.05μm. The sampling inspection of laser pointer has the specific requirement.