Shack Hartmann wave-front measurement with a large F-number plastic microlens array

Area of Science:

• Optics and Photonics
• Optical Metrology

Background:

• Shack-Hartmann wave-front sensing is crucial for optical system characterization.
• Improving the accuracy and reproducibility of wave-front measurements is an ongoing challenge.

Purpose of the Study:

• To develop and evaluate a new plastic microlens array for Shack-Hartmann wave-front sensors.
• To enhance the precision of wave-front measurement through improved sensor design.

Main Methods:

• Fabrication of a plastic microlens array with 900 individual 300 µm × 300µm lenslets and a 10 mm focal length.
• Utilizing a deformable mirror to introduce controlled aberrations (defocus, astigmatism) for testing.
• Measuring laser wave fronts using the developed Shack-Hartmann sensor and averaging frame memories to reduce spot centroiding error.

Main Results:

• The microlens array consistently produces a 60 µm focal spot size with constant peak intensity.
• Achieved measurement accuracy better than λ/20 (root mean square).
• Demonstrated reproducibility better than λ/50 (root mean square) for wave-front measurements (λ = 632.8 nm).

Conclusions:

• The new plastic microlens array significantly improves Shack-Hartmann wave-front sensor performance.
• The developed sensor offers high accuracy and excellent reproducibility for optical wave-front analysis.
• This technology has potential applications in adaptive optics and optical testing.