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.

Electronic autocollimator measurement offers speed, accuracy and cost-effectiveness, making it one of the most practical procedures available. Widely used in workshops, tool rooms, inspection departments and quality control laboratories, these highly sensitive instruments are designed to measure extremely small angular displacements, squareness, twist and parallelism.

Current technology allows has improved the autocollimation instrument to allow for direct measurements of incoming laser beams. This capability opens allows for inter-alignment between optics, mirrors and lasers. This fusion between the century-old technology of autocollimation with recent laser technology results has resulted in a versatile instrument capable of measuring the inter-alignment between multiple line of sights with 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.

The concept of autocollimation as an optical instrument was conceived about a century ago for non-contact measurements of angles, as done in total stations. 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.

Recent developments in optical metrology have extended the role of the autocollimator beyond single-axis angular measurement into multi-functional, integrated measurement systems. By combining digital imaging sensors, multi-wavelength illumination, and computational analysis, modern autocollimator-based instruments can perform several optical diagnostics traditionally requiring multiple standalone laboratory devices.

Such systems use the autocollimator’s inherent sensitivity to angular deviations as a shared reference framework for additional measurements, including laser beam profiling, wavefront characterization, multi-axis alignment, and geometric verification. By operating within a common optical axis and coordinate system, these instruments reduce cumulative alignment errors that arise when measurements are distributed across separate devices.

Integrated autocollimator-based systems are increasingly designed for in-situ and in-line use, enabling real-time alignment and verification during optical assembly or laser manufacturing processes. This approach contrasts with conventional optical laboratories, where measurements are typically performed offline and sequentially.

The concept has been implemented in various hybrid optical metrology platforms developed by manufacturers and as well described in academic and patent literature addressing automated alignment and smart manufacturing.

The front runner of this technology is the so called Total Station Autocollimator implementing into one instrument up to 10 different instruments to be chosen by a press of a button.

As optical systems increase in complexity, integrated autocollimator-based metrology is increasingly viewed as a practical method for consolidating multiple optical measurements into a single, traceable instrument.

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:

• Retroreflector 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.

• Autocollimation
• Collimator

• Lowell, Tom. "Small Angles and Autocollimators". Vermont Photonics. Archived from the original on 28 June 2022. Retrieved 7 May 2006.
• Morel, Jerrat. "Principles of Operation". Micro-Radian Instruments. Archived from the original on 7 May 2007. Retrieved 14 May 2007.
• Aharon, Oren. "Metrology system for inter-alignment of lasers, telescopes, and mechanical datum". Duma Optronics. Retrieved 12 October 2015.
• Aharon, Oren. "Telescopic Analyzing System Tests Laser Collimation and Propagation". Duma Optronics. Archived from the original on 5 June 2017. Retrieved 5 June 2017.
• Aharon, Oren. "Laser Autocollimator and Bore Sighting". Duma Optronics. Archived from the original on 24 July 2014. Retrieved 21 July 2014.
• O. Aharon and I. Vishnia (2021). "The Hybrid Autocollimator". Photonicsviews. 18. Photonics Views: 60–63. doi:10.1002/phvs.202100001. S2CID 234030641.
• O. Aharon (2022). "Total Station Autocollimator for Photonics Professionals". Novus Light. Retrieved 28 February 2022.
• Möller, T. (2018). "Integrated optical metrology for alignment and inspection in photonics manufacturing". Proceedings of SPIE. 10678. SPIE. doi:10.1117/12.2300123.