What principles does the autocollimator use to detect?

Autocollimator is an instrument for measuring optical straightness. It is widely used for small angle measurement and flatness measurement of flat plates. What are the principles of the autocollimator for testing? Let's take a look.


The system has a light source followed by a projection bulkhead. The light source is LED (usually 670 nm, recently introduced into the infrared version). After passing through the spectroscope, the light enters the target lens and is collimated before leaving the instrument. The collimation refers to the mask distance projected from the lens surface on the focal length.


The projected collimated light is reflected back by the reflector or other high-quality reflectors and captured by the objective lens. The returned image is collected on a high-quality CCD detector. Because the detector is highly sensitive, even the very weak reflection will be captured and displayed. In the original line of sight, the offset A of the mirror image is 2A.


The deviation of azimuth and elevation can be determined and calculated by computer. In addition, the results can be clearly displayed on the screen. The resolution can be less than 0.01 arcsec. As a rule of thumb, the higher the FL, the higher the resolution. Therefore, the smaller the field of view, the more difficult it is to obtain the reflected signal. Electronic methods provide completely objective advantages in data recording and computer interfaces different from optical autocollimators, which are more cumbersome and inaccurate.


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