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Application of Piezo Technology in Interferometry

Update time：2022-06-28 11:45:37Clicks：1136second

Interferometry technology is a measurement technology based on the principle of light wave interference. In the field of modern precision measurement, many measurement tasks are achieved by interference. For the solution of many measurement problems, optical interferometry is currently the only feasible method. Compared with the general optical imaging measurement technology, interferometry has the characteristics of large range, high sensitivity and high precision. With the continuous progress of science and technology, especially the emergence of laser technology and its application in the field of interferometry, the interferometry technology has been significantly improved in terms of range, resolution, and measurement accuracy. From classical optical techniques to adaptive optics engineering, the fields of application of modern interferometry techniques are constantly expanding.

Modern image sensing and computer technology have also provided a huge boost to the development of interferometry, which has brought interferometric image reading and processing into a new era.

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Fizeau Interferometer

Fizeau thickness interferometer is a kind of commonly used interferometer, mainly used to detect the surface shape measurement of optical plane, spherical and aspherical surface, measurement of spherical radius of curvature and measurement of wavefront transmission quality of various lenses, prisms and lens systems and optical systems.

The interference principle is shown in the figure. The light emitted by the monochromatic light source is converged on the circular aperture diaphragm by the lens, and the diaphragm is located on the focal plane of the collimating tube objective lens. The parallel beam emitted from the collimating objective lens is reflected back on the lower plane of the reference plane with wedge and the upper plane of the measured plane, and then passes through the collimating objective lens and the objective lens to form a small hole of the circular aperture diaphragm on the focal plane of the eyepiece of two images. Adjust the micro-displacement drive table where the measured part is located so that the two images coincide. If a CCD camera is used instead of the eyepiece, the interference fringes can be collected and processed by a computer imaging system.

Schematic diagram of the transmission type Fizeau interferometer

Fizeau interferometer has two kinds of plane and spherical, the former is composed of a beam splitter, a collimating objective and a standard plane, and the latter is composed of a beam splitter, a finite conjugate distance objective and a standard spherical surface. The monochromatic beam is partly reflected on a standard plane or standard sphere as a reference beam; partly transmitted and passed through the DUT is a detection beam. The detection beam self-collimates and returns to coincide with the reference beam to form equal-thickness interference fringes. The Fizeau plane interferometer can detect the surface shape and uniformity of the plate or prism. The spherical shape and its radius of curvature can be detected by the Fizeau spherical interferometer, and the measurement accuracy of the latter is about 1 micron; it can also detect the wavefront aberration of infinite and finite conjugate distance lenses.

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芯明天压电移相器

In recent years, with the progress and development of digital technology and image acquisition technology, various new types of Fiseau laser interferometers have appeared continuously, and domestic and foreign companies have also launched corresponding products. Combining its own technical advantages and R&D capabilities in the field of micro-displacement phase-shifting actuators, CoreMorrow has designed a variety of products for interferometric measurement research and development. Compared with motor-driven and electromagnetic-driven products, piezoelectric micro-displacement mechanisms have small size and simple structure. High precision, high resolution (nm level), good rigidity, easy to control operation and low energy consumption, no heat, no noise and so on.

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CoreMorrow P77 series piezo phase shifters are specially designed for optical detection phase shifting applications. The travel range under test can be up to 100µm, and the load capacity can be up to 25kg. It is suitable for optical detection equipment of various lenses and lenses. It can be customized according to the customer's equipment application requirements.