High-precision focus detection device for long-focus lens

Abstract

The invention discloses a high-precision focus detection device for a long-focus lens, which comprises a laser, a microscope objective, a pin hole, a first Ronchi grating, the long-focus lens to be detected, a second Ronchi grating, ground glass and a CCD (Charge Coupled Device) camera. Light emitted by the laser passes through the microscope objective and the pin hole to form a divergent beam and the divergent beam enters the first Ronchi grating and then passes through the long-focus lens to be detected and the second Ronchi grating; the second Ronchi grating is placed at a certain talbot-order position of the first Ronchi grating, so that Moire fringes can be formed on a talbot image of the first Ronchi grating and the second Ronchi grating; and the fringes are acquired by the CCD camera and the focus of the lens to be detected can be obtained by calculating angles of the fringes. The high-precision focus detection device has a simple structure, is easy to implement, has high precision, can be used for detecting the long-focus lens and accurately measuring the focus in an optical system and particularly can be used for accurately measuring the focus of the large-caliber long-focus lens (the focus is in the range of meters and dozens of meters), so that an error caused by the scanning detection is avoided.

Description

technical field [0001] The invention belongs to the field of optical testing, in particular to a focal length detection device of a high-precision long focal length lens. Background technique [0002] In the fields of optics, astronomy and military affairs, the long focal length lens is a very critical basic component, playing an increasingly important role, and the required focal length is getting longer and the aperture is getting larger and larger. In large systems, such as the National Ignition Facility, long focal length lenses are the key light-gathering elements, and these lenses have a focal length of up to forty meters. The use of long focal length lenses requires corresponding detection technology, but there are still many difficulties in high-precision detection, especially the measurement accurate to a few millimeters or even hundreds of microns. , but with the increase of the focal length, the use of spherometer detection will be inaccurate. In addition, high-...

AI Technical Summary

Problems solved by technology

The use of long focal length lenses requires corresponding detection technology, but there are still many difficulties in high-precision detection, especially the measurement accurate to several millimeters or even hundreds of microns. , but with the increase of the focal length, it is inaccurate to use the spherometer to detect

In addition, high-precision detection is difficult to eliminate the influence of external interference, especially air turbulence and external vibration, and the aberration of the optical path in the detection system itself increases with the increase of the focal length. Accuracy measurement

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