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The electronic autocollimator is a high precision angle measurement instrument capable of measuring angular deviations with accuracy down to fractions of an arc-second. It can be used in numerous applications in a variety of areas. Some examples include: perform a machine alignment, measurement of slide ways, precision machines, accurate optical assemblies, alignment of optical setups and more. Measuring with an electronic autocollimator is fast, easy, accurate, and will frequently be the most cost effective procedure. Used extensively in workshops, tool rooms, inspection departments and quality control laboratories worldwide, these highly sensitive instruments will measure extremely small angular displacements, squareness, twist and parallelism. ==Autocollimation principle== The system has a light source followed by a projection reticle. The light source is LED (usually 670 nm). After passing through the beam splitter, the light enters the objective lens where it is collimated prior to exiting the instrument. Collimation means that the projected reticle is exactly one focal length away from the main surface of the objective lens. The projected collimated light is back reflected by a mirror, or other high-quality reflective surface, and is captured by the objective lens. The returned image appears in sharp focus on the high quality CCD detector. Due to the detector high sensitivity even very faint back reflection will be captured and displayed. Deviation of the mirror by an amount A causes deviation on the original line of sight by an amount of 2A. Assuming the amount of deviation of the reflective surface the focal length is denoted by FL, then mirrors’ deviation is to be determined from the relationship: A=X/2FL From the equation it is apparent that measuring mirror angular deviation is independent of the distance between the instrument and the reflecting surface. Deviations in azimuth and elevation can then be electronically determined and calculated by a computer. Furthermore, the results are than clearly displayed on its screen. Resolution down to 0.01 arcsec is achievable. As a rule of thumb, the higher the FL, the higher the resolution. As a result, the field of view is smaller and thus it is more difficult to acquire the reflected signal acquisition. The electronic method offers the advantage of complete objectivity in data recording, as well as a computer interface unlike optical autocollimators which are bulkier and less accurate. In a telescopic application, where the telescope is calibrated to infinity, the angle of movement is A=X/FL. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electronic autocollimators」の詳細全文を読む スポンサード リンク
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