Phase response measurement of spatial light modulators based on a Shack-Hartmann wavefront sensor

Area of Science:

• Optics and Photonics
• Metrology
• Optical Instrumentation

Background:

• Spatial light modulators (SLMs) are crucial for optical systems.
• Traditional phase response measurements using interferometers are susceptible to environmental disturbances.
• Accurate phase response characterization is essential for SLM performance.

Purpose of the Study:

• To propose and validate a Shack-Hartmann wavefront sensor (SHWS) method for measuring SLM phase response.
• To compare the accuracy and robustness of the SHWS method against traditional interferometer techniques.
• To demonstrate the suitability of SHWS for real-time, vibration-insensitive SLM characterization.

Main Methods:

• Implementation of a Shack-Hartmann wavefront sensor with a 73x73 lenslet array.
• Measurement of SLM phase modulation depth using the SHWS method.
• Comparison of SHWS measurements with results obtained from a Twyman-Green interferometer.

Main Results:

• The SHWS method measured a phase modulation depth of 1.7581λ.
• The Twyman-Green interferometer measured a phase modulation depth of 1.7993λ.
• A small difference of 0.0412λ (2.29% relative error) was observed, demonstrating equivalent accuracy.

Conclusions:

• The SHWS method provides phase modulation accuracy comparable to Twyman-Green interferometers.
• SHWS offers advantages in simplicity, compactness, robustness, real-time capability, and vibration insensitivity.
• The SHWS method is a promising technique for future SLM phase response detection.