What are the inspection devices for off-axis parabolic mirrors?

Technical Specification of Core Inspection Equipment for UltraOpto OFF-AXIS PARABOLIC MIRROR

UltraOpto OFF-AXIS PARABOLIC MIRROR is a core component in high-end optical systems such as deep ultraviolet lithography, laser collimation, and astronomical observation. Its surface shape accuracy, curvature radius, and reflectivity uniformity directly determine the quality of light transmission. To ensure that the product performance meets the design standards, multiple high-precision professional inspection devices are required to verify the key indicators in all dimensions. The following is a description of the core inspection equipment and their application scenarios.

I. Geometric Precision Inspection Equipment

1. Phase-Shifting Interferometer

Core inspection indicators: Surface shape accuracy, surface shape deviation, surface roughness of the off-axis parabolic mirror

Equipment advantages: Measurement accuracy can reach λ/[email protected] (helium-neon laser wavelength), capable of precisely capturing microscopic contour deviations on the mirror surface, distinguishing between rotational symmetric and asymmetric errors in the surface shape, meeting the high-precision inspection requirements of off-axis components.

Application scenarios: Final inspection of the mirror surface after grinding and polishing to ensure that the surface shape accuracy meets the design requirements (such as λ/20@193nm deep ultraviolet band compatibility standard).

2. Coordinate Measuring Machine (CMM)

Core inspection indicators: Off-axis amount, parabolic vertex position, aperture size, thickness tolerance, edge chamfer size

Equipment advantages: Utilizes contact or non-contact probes, with a measurement accuracy of ±0.001mm, capable of quickly obtaining the three-dimensional geometric parameters of the reflector and verifying the consistency between the actual processing dimensions and the CAD design model.

Application scenarios: Batch spot checks of the key geometric dimensions of the reflector after the forming process to ensure the matching of installation interfaces.

3. Laser Tracker

Core inspection indicators: Curvature radius, spatial attitude accuracy of large-aperture off-axis parabolic mirrors

Equipment advantages: Wide measurement range (up to tens of meters), high precision (angle measurement accuracy ≤ 0.1arcsec), capable of completing three-dimensional spatial coordinate measurements of large-sized components in a non-contact state, avoiding damage to the mirror surface caused by contact measurement.

Application scenarios: Final inspection of large-aperture (≥200mm) off-axis parabolic mirrors at the factory to verify the deviation of the curvature radius from the design value.

II. Optical Performance Inspection Equipment

1. Laser Reflectometer

Core inspection indicators: Reflectivity and reflectivity uniformity in the target band (such as 193nm, 248nm)

Equipment advantages: Switchable deep ultraviolet, visible light, infrared, and other multi-band laser light sources, with a measurement accuracy of ±0.0001%, capable of performing point-by-point scanning of the reflectivity in different areas (center, edge) of the mirror surface, generating a reflectivity uniformity distribution map.

Application scenarios: Full-band reflectivity inspection of the reflector after coating to ensure that the reflectivity in the 193nm deep ultraviolet band is stable and meets customer requirements (such as 99.99% or above).

2. Spectrophotometer

Core inspection indicators: Spectral reflectance curve, band applicability of the reflector

Equipment advantages: Wide spectral coverage (190nm-250nm), capable of quickly drawing the curve of reflectance variation with wavelength, intuitively judging the performance of the reflector in non-target bands, and verifying the rationality of the film system design. Application scenarios: During the R&D stage, spectral performance tests are conducted on new mirror coating formulas to optimize the film structure.

3. Collimator + Wavefront Sensor

Core detection indicators: Beam collimation accuracy of the mirror, wavefront distortion

Equipment advantages: Simulates actual application scenarios. After the laser beam is reflected by an off-axis parabolic mirror, the wavefront sensor detects the beam wavefront shape and quantifies the wavefront distortion value (e.g., RMS value ≤ 0.05λ).

Application scenarios: Performance verification before final assembly to ensure that the mirror has no significant wavefront distortion in the actual optical path.

III. Environmental Reliability Testing Equipment

1. High and Low Temperature Humidity Test Chamber

Core detection indicators: Temperature and humidity stability of the mirror

Equipment advantages: Can simulate temperature cycles from -40°C to 85°C and a humidity environment of 85% RH. Through long-term aging tests, it detects the surface shape changes and adhesion decline of the mirror film layer under extreme conditions.

Application scenarios: Reliability testing to verify the long-term stability of the product in industrial-grade environments.

2. Laser Damage Threshold Tester (LIDT Tester)

Core detection indicators: Laser damage threshold

Equipment advantages: Can output high-power pulsed lasers (such as 193nm excimer lasers). By gradually increasing the laser power density, it detects the damage critical point of the mirror film layer or substrate and quantifies the laser damage resistance (e.g., ≥500mJ/cm²@193nm, 10ns pulse).

Application scenarios: Specialized testing for products adapted to high-power laser systems to ensure no performance degradation under strong laser irradiation.

IV. UltraOpto Testing Advantages

Full-process testing coverage: From substrate pretreatment to final product shipment, 100% spot checks are conducted on key processes, and core indicators are verified in all dimensions;

High-precision equipment guarantee: Utilizes imported high-end testing equipment, with measurement accuracy on par with international advanced levels;

Customized testing solutions: Can build specialized testing platforms based on customer-specific requirements to meet personalized indicator testing needs.