Instruments for testing under-mounted beam splitters

Precision optical profilers, interferometers, and polarization analyzers are commonly used to test under-mounted beam splitters for wavefront quality, splitting ratio, and polarization performance. Key Testing Instruments1. Optical Interferometers Interferometers, such as those offered by Zygo, use low-coherence or laser-based interference to measure surface flatness, wavefront distortion, and parallelism of beam splitters with nanometer precision.

They are ideal for under-mounted configurations because they can capture detailed topography without disassembling the optical system. 2. Polarization and Extinction Ratio Analyzers For polarizing beam splitters, instruments that measure extinction ratio and polarization purity are essential.

These analyzers quantify the ratio of P- to S-polarized light in transmitted and reflected beams, ensuring the splitter meets design specifications. 3. Power and Intensity Meters Non-polarizing and dichroic beam splitters require testing of splitting ratios.

High-precision photodetectors or power meters measure the intensity of transmitted and reflected beams to verify the intended split, including wavelength-dependent performance for dichroic splitters. 4. Wavefront Sensors Wavefront sensors can detect aberrations or distortions introduced by the beam splitter.

These are particularly useful for plate or pellicle splitters where thin-film interference or membrane tension may affect beam quality. 5. Displacement and Alignment Tools For under-mounted or integrated beam splitters, displacement interferometers or precision alignment stages allow measurement of lateral or angular displacement between input and output beams, ensuring proper alignment within optical assemblies.

Considerations for Under-

Mounted TestingNon-contact measurement is preferred to avoid damaging delicate pellicle or thin-film splitters. Wavelength-specific testing may be required for dichroic or multi-band splitters. Environmental control (temperature, vibration) is critical for high-precision interferometry.

Custom fixtures may be needed to access under-mounted splitters without disassembly.

Summary

Testing under-mounted beam splitters typically involves a combination of interferometry for wavefront and surface quality, polarization analysis for polarizing splitters, and power/intensity measurements for splitting ratios. Leading instruments include Zygo optical profilers for nanometer-scale surface mapping and Keysight displacement or polarization beam splitters for precise alignment and performance verification. These tools ensure that under-mounted beam splitters meet optical specifications without compromising system integrity.