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An autocollimator is an
optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common examples include periscopes, microscopes ...
for non-contact measurement of
angle In Euclidean geometry, an angle is the figure formed by two Ray (geometry), rays, called the ''Side (plane geometry), sides'' of the angle, sharing a common endpoint, called the ''vertex (geometry), vertex'' of the angle. Angles formed by two ...
s. They are typically used to align components and measure
deflection Deflection or deflexion may refer to: Board games * Deflection (chess), a tactic that forces an opposing chess piece to leave a square * Khet (game), formerly ''Deflexion'', an Egyptian-themed chess-like game using lasers Mechanics * Deflection ...
s in optical or mechanical systems. An autocollimator works by projecting an image onto a target
mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
and measuring the deflection of the returned image against a scale, either visually or by means of an electronic detector. A visual autocollimator can measure angles as small as 1 arcsecond (4.85 microradians), while an electronic autocollimator can have up to 100 times more resolution. Visual autocollimators are often used for aligning
laser rod The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a ...
ends and checking the face parallelism of optical windows and wedges. Electronic and digital autocollimators are used as angle measurement standards, for monitoring angular movement over long periods of time and for checking angular position repeatability in mechanical systems. Servo autocollimators are specialized compact forms of electronic autocollimators that are used in high-speed servo-feedback loops for stable-platform applications. An electronic autocollimator is typically calibrated to read the actual mirror angle.


Electronic autocollimator

The electronic autocollimator is a high precision angle measurement instrument capable of measuring angular deviations with accuracy down to fractions of an arcsecond, by electronic means only, with no optical eye-piece. 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.


Laser analyzing autocollimator

Today, a new technology allows to improve the autocollimation instrument to allow direct measurements of incoming laser beams. This new capability opens a gate of inter-alignment between optics, mirrors and lasers. This technology fusion between a century-old technology of autocollimation with recent laser technology offers a very versatile instrument capable of measurement of inter-alignment between multiple line of sights, laser in respect to mechanical datum, alignment of laser cavity, measurement of multiple rollers parallelism in roll to roll machinery, laser divergence angle and its spatial stability and many more inter-alignment applications.


Total station autocollimator

The concept of autocollimation as an optical instrument was conceived about a century ago for non-contact measurements of angles. Hybrid technology fulfills a need recently developed by novel photonics applications has created for the alignment and measurement of optics and lasers. Implementing motorized focusing offers an additional measurement dimension by focusing on the area to be examined and performing alignment and deviations from alignment on the scale of microns. This is relevant in the adjustment phase as well as final testing and examination phases of integrated systems. Recent progress has been made in with the aim to serve the photonics AR/VR industry, involving development in interalingment, fusion of several wavelengths including NIR into one system, and measurements of multi laser array such as VCSEL in respect with other optical sensors, to improve angular accurate optical measurements to a resolution of 0.01 arcseconds.


Typical applications

An electronic autocollimator can be used in the measurement of straightness of machine components (such as guide ways) or the straightness of lines of motion of machine components. Flatness measurement, of granite surface plates, for example, can be performed by measuring straightness of multiple lines along the flat surface, then summing the deviations in line angle over the surface. Recent advancements in applications allow angular orientation measurement of wafers. This could also be done without obstructing lines of sight to the wafer's surface itself. It is applicable in wafer measuring machines and wafer processing machines. Other applications include: * Aircraft assembly jigs * Satellite testing * Steam and gas turbines * Marine propulsion machinery * Printing presses * Air compressors * Cranes * Diesel engines * Nuclear reactors * Coal conveyors * Shipbuilding and repair * Rolling mills * Rod and wire mills * Extruder barrels Optical measurement applications: * Retro reflector measurement * Roof prism measurement * Optical assembly procedures * Alignment of beam delivery systems * Alignment of laser cavity * Testing perpendicularity of laser rods in respect to its axis * Real time measurement of angular stability of mirror elements.


See also

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Autocollimation {{more citations needed, date=November 2021 Autocollimation is an optical setup where a collimated beam (of parallel light rays) leaves an optical system and is reflected back into the same system by a plane mirror. It is used for measuring small ...
*
Collimator A collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spati ...


References

* * * * * *{{cite journal , last=O. Aharon and I. Vishnia, year= 2021, title=The Hybrid Autocollimator , journal= Photonicsviews, volume= 18, pages= 60–63, publisher=Photonics Views , doi= 10.1002/phvs.202100001, s2cid= 234030641, url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/phvs.202100001 , accessdate=23 February 2021 Optical instruments Optical metrology Measuring instruments