The technological revolution of wavefront sensor----four-wave shear interference technology

The technological revolution of wavefront sensors

----- Four-wave shear interference technology

Text: Chen Changying, Technical Engineer of Shanghai Haoquan Photoelectric Equipment Co., Ltd.

Abstract:

The wavefront sensor (wavefront analyzer) is one of the most important components of the adaptive optics system and determines the final modulation result of the adaptive optics system. At the same time, wavefront detectors detect wavefront aberrations in complex adaptive optical systems such as laser, astronomy, microscopy, and ophthalmology, iris positioning aberration guidance, large-caliber high-precision optical component detection, and collimator/telescope system detection. It plays an increasingly important role in the fields of assembly, infrared, near-infrared detection, laser beam performance, wavefront aberration, M^2, intensity detection, and surface quality inspection of high-precision optical components. The research and development team of France PHASICS has broken through the barriers of traditional technology and successfully developed the world's highest resolution four-wave shear interference wavefront detector . This paper briefly introduces the principle and typical application of wavefront sensor and the principle of four-wave shearing interference technology. It compares the characteristics of wavefront analyzer and traditional Hartmann sensor.

INTRODUCTION:

The wave front sensor (Wave Front Sensor) can be divided into three stages according to the history of its technological development: In the first stage, in 1900, German scientist Hartman used the boring technique to make the world's first available. For detecting the wavefront sensor. In the second phase, in 1971 RKShack developed a more accurate Shack-Hartman wavefront analyzer for lens arrays. In 2000, the French Phasics R&D team successfully developed 4-Wave Lateral Shearing Interferometry using four-wave shear interferometry . The wavefront detector has high resolution (400X300) and high dynamic range ( 500 um), achromatic , high sensitivity , high relative accuracy (2nm RMS), no calibration, small size, easy operation. The French phasics wavefront phase difference instrument, which is represented by Shanghai Quantitative Photoelectric Equipment Co., Ltd., can measure the wavefront error of the imaging system in real time, and then convert these measurement data into control signals of the adaptive optical system, and real-time the optical characteristics of the imaging system. Control, real-time correction of the wavefront deformation of the incident beam, thereby compensating for the wavefront distortion caused by atmospheric turbulence, so that the objective lens obtains the target image close to the diffraction limit.

Principle of four-wave shear interference technology:

The basic principle of the shear interference technique is to divide the wavefront of the laser to be detected into two beams, one of which generates some misalignment with respect to the other beam, and the two beams of dislocations each maintain a complete wavefront information to be measured, overlapping each other. After the interference phenomenon occurs, the CCD/CMOS camera receives the interference pattern and performs corresponding calculation and analysis, thereby analyzing the phase distribution before the wave to be measured and the intensity distribution by using the correlation calculation of the Fourier transform. The density based on interference fringes is sensitive to the slope of the wavefront, so the wavefront sensor has a greater range of deviation from the traditional Hartmann sensor in detecting the wavefront.

Typical application of wavefront sensors

In the process of transmission, light passes through different media. Different media have a variety of changes in the wavefront of the light due to the uneven distribution of the constituent materials. The adaptive system has emerged. As an important part of the adaptive system, the detection accuracy, dynamic range and other factors of the wavefront sensor restrict the final modulation result of the adaptive system. Because the shearing interference wavefront analyzer has the advantages of high resolution, high detection precision, fast detection speed, simple operation, and direct three-dimensional display of wavefront distortion mode, it has been widely used.

1. Adaptive optical system real-time wavefront detection

In the adaptive optics system, the Phasics wavefront sensor is used to detect accurate wavefront distortion information, which is fed back to the wavefront correction system to compensate the distortion of the wavefront to be measured, thereby effectively reducing the influence of turbulence and compensating for atmospheric turbulence. Light wave phase disturbance.

2 , laser beam performance, wavefront aberration, M^2 , intensity, etc.

Laser beam quality is an important technical index parameter of the laser. It mainly refers to the field strength distribution and variation of the cross section of the beam. The main parameters include: beam diameter, propagation mode, far field divergence angle, and spot direction drift. Studying the distortion of the wavefront phase is the main basis for analyzing the deformation of the cavity in the laser device. Improving the wavefront performance is an important means to improve the beam quality.

The wavefront analyzer can be used for laser wavefront detection, and can obtain the laser intensity distribution and other laser beam quality parameters, providing a high precision, high sensitivity, real-time 3D for simultaneous detection of laser wavefront and beam quality. Show, a new and easy way.

3 , precision optical components testing

With the advancement of technology, people are increasingly demanding the production specifications of precision optical components. The wavefront detector can detect precise optical components and obtain accurate monitoring data in real time. For precision optical components. Production has undoubtedly produced a new technological revolution. Compared with the traditional interferometer to detect the wavefront of optical components, Phasics wavefront analyzer is more suitable for the detection of aspherical lenses with large aberrations and spherical aberration. The wavefront analyzer has the advantages of no standard parts, small size, high precision, large numerical aperture (up to 0.75), and so on. Shanghai Haoquan Photoelectric Equipment Co., Ltd. can make personalized wavefront sensor testing solutions according to the actual testing needs of customers.

4 , laser plasma detection and analysis

The French Phasics company (Quantity Photoelectric Agent) SID4 series Plasma Diagnosis is a portable, high sensitivity, high precision plasma analyzer. Based on the four-wave shear interference technology of wavefront analysis, the product can detect the electron density, mode and propagation mode of the plasma generated by laser. Plasma generation, diffusion processes, and plasma quality factors can be monitored in real time. It can better provide customers with optimized data support in nozzle design, laser pulse illumination, air pressure, uniformity and so on.

In addition, wavefront analyzers are widely used in infrared and near-infrared detection; detection and adjustment of collimator/telescope systems; satellite remote sensing imaging, bioimaging, and thermal imaging; spherical and aspheric optical elements Device detection (plane, spherical, lens); iris positioning aberration guidance; large-caliber high-precision optical component detection; laser communication field; aerospace and other fields.

Wavefront detector product line

Medical Surgery Products

Scalpel Blades,Surgical Blade,Safety Scalpel,Surgery Blade

Surgimed Medical Supplies Co.,Ltd , https://www.surgimedcn.com