Alignment Holograms
DIOPTIC is a pioneer in the development and implementation of CGHs. In collaboration with the Max Planck Institute for Extraterrestrial Physics, DIOPTIC has developed a method for accurately localizing the position of optical elements in space with sub-µm precision. This technology has also been successfully deployed in industrial applications.
Features and Benefits
Precise Alignment Using Multi-Zone CGHs
Multi-zone CGHs enable the precise alignment of individual components of lens systems and reflector telescopes. Even systems whose detection spectrum lies far outside of visible light (e.g., radio telescopes) or whose operating conditions cannot be easily reproduced during production (e.g., temperature in space telescopes) can be adjusted with the same accuracy.
Individual, Application-Specific Design
As part of the interferometric alignment of a lens, corresponding CGH zones are specifically aligned for each lens surface. The target position and orientation are stored in the sub-holograms. Each CGH zone generates an interference signal for a specific degree of freedom of a specific element of the optical assembly. By optimizing the interference signal, the lens can be precisely adjusted in position and tilt.
Developed and Tested for Space Conditions
The principle of interferometric precision alignment was successfully used in the production of the telescope lens for the ESA Euclid Space Mission. One particular challenge was that the telescope’s five lenses only produce a sharp image at an operating temperature of -140°C. As a result, it was not possible to optimize the imaging performance during lens assembly. Our multi-zone alignment CGH enabled the target position of each individual lens to be adjusted to micrometer accuracy at room temperature, taking thermal expansion into account.
Convincing to Use
The new method of interferometric precision alignment is based on a CGH with several zones. One lens element to be adjusted is targeted through each zone. This allows optical systems to be adjusted in space with an accuracy of a few µm.
Precision alignment with multi-zone CGHs: Our multi-zone CGHs are the ideal solution for aligning optical elements in space with an accuracy of a few micrometers. Once the lens is correctly positioned and oriented, an interference pattern is generated by the associated CGH zone. The alignment is done by optimizing the interference signal. Good imaging as an adjustment criterion is not required here.
Optimal positioning of all elements: The interferometric alignment of a lens assembly uses multiple CGH zones which are each designed for a corresponding lens surface. At least one diffractive subzone is provided on the substrate for each optical element to be adjusted and each individual lens surface. The alignment zones of all lenses are produced on a substrate with sub-µm accuracy, ensuring that all components are positioned optimally relative to one another.
With the help of our alignment CGHs, we have succeeded in adjusting the endoscope for observing the divertor plates of the Wendelstein 7-X fusion device with high precision.
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