Researchers from the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences have developed a method to improve the quality of the lenses of large telescopes. For this, computer-synthesized holograms and special tags are used. Hi-Tech studied the work of scientists published in the journal Sensors.

For quality control of mirrors of large telescopes and other space optics, special images created with a laser on quartz plates have long been used. It is important that the holograms themselves are sufficiently accurate. To solve this problem, Russian photonics have developed a method for recording specialized marks in the field of a hologram. And this happens in the process of recording it on the disc.

These marks are micro-lattices, the points in which are staggered. When light passes through them, a complex diffraction pattern is formed from many beams of light.

The process of recording microgrids is divided into several stages. To begin with, the first part of the “marks” is recorded, and even before the hologram. Then, when the hologram recording begins, the second part of the microgrids is added at predetermined places. The process of creating holograms takes up to 12 hours.

When the hologram recording is complete, a laser beam is passed through each mark, and then the diffraction pattern is analyzed. If the picture is disturbed, that is, the microlattices have shifted relative to each other during recording, then the hologram will also be inaccurate. If the picture is accurate, then the plate can be used to test space optics as a reference sample.

“Our proposed method can determine the errors in the image with a scale of up to 10 nm, which allows us to guarantee the accuracy of holograms. This is very important when used to test the quality of telescope mirrors. For example, our institute has produced holograms that were used as standards for polishing the surface of the largest mirror in Russia – 6 m in diameter – of the Large Azimuth Telescope (BTA). Also, our laboratory has created holograms for a similar test of the mirrors of the James Webb Space Telescope. ”

Ruslan Shimansky, Researcher, Institute of Automation and Electrometry, SB RAS