CGH Null Correctors (Computer-Generated Hologram Null Correctors) are advanced optical testing devices used to measure and correct aberrations in precision optical systems, such as aspheric and freeform lenses or mirrors. They employ diffraction-based technology to generate wavefronts that perfectly match the ideal shape of the optical component under test, enabling highly accurate null testing.
CGH Null Correctors function by using a computer-generated hologram—a precision diffraction grating—to produce a reference wavefront. When laser light passes through the CGH, it diffracts to create a wavefront that corresponds to the inverse of the expected aberration of the test optic. Any deviations between this reference wavefront and the actual wavefront reflected from the test surface are captured by a detector, such as an interferometer. These deviations are analyzed to quantify errors in the optical surface.
Key working principles include:
Wavefront Matching: The CGH generates a custom wavefront that “nulls” out the ideal shape of the test optic, turning the reflected wavefront into a flat or simple spherical reference for easy measurement.
Diffraction-Based Calibration: The hologram is designed with precise patterns that direct light into specific orders, with the first diffraction order used for testing.
High-Resolution Error Mapping: Interferometric data provides detailed surface error profiles, allowing for corrective polishing or alignment.
Our CGH Null Correctors are engineered for maximum precision and compatibility with industry-standard interferometers. Below are the key product parameters:
Key Features:
Diffraction efficiency > 35% in the first order
Sub-nanometer wavefront accuracy
Compatible with wavelengths of 632.8 nm (HeNe laser) or 1064 nm (IR laser)
Custom-designed for each specific optic
Material: Fused silica or quartz substrate
Size range: 25 mm to 500 mm diameter
Parameter Table:
| Parameter | Specification |
|---|---|
| Wavefront Accuracy | < λ/50 RMS (λ = 632.8 nm) |
| Alignment Tolerance | < 10 arcsec in tilt and decenter |
| Line Placement Accuracy | < 50 nm |
| Laser Compatibility | HeNe, IR, or visible laser sources |
| Operating Distance | Customizable from 50 mm to 2000 mm |
| Surface Quality | 10-5 scratch-dig |
CGH Null Correctors are essential in aerospace, astronomy, and high-end imaging industries for validating large telescopes, EUV lithography optics, and precision mirrors. Their ability to test complex optical surfaces without physical null lenses makes them versatile and cost-effective.
Our products combine decades of optical engineering expertise with state-of-the-art lithography manufacturing processes. Each CGH is meticulously designed and verified to ensure traceable accuracy and repeatable results.
If you are very interested in Ningbo Zhixing Optical Technology's products or have any questions, please feel free to contact us.
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