Wavefront Characteristics of a Digital Holographic Optical Element

Area of Science:

• Optical Engineering
• Holography
• Metrology

Background:

• Holographic optical elements (HOEs) offer versatile optical functions.
• Digital recording methods are emerging for HOE fabrication.
• Evaluating the performance of digital HOEs against traditional optical elements is crucial.

Purpose of the Study:

• To digitally record a holographic optical element (HOE) with spherical mirror properties.
• To compare the optical performance and wavefront characteristics of a digital HOE with analog HOEs and a spherical mirror.
• To assess the effectiveness of phase maps for visualizing wavefront distortions.

Main Methods:

• A 50 × 50 mm digital HOE was fabricated on a silver halide photoplate using wavefront printing.
• Optical performance was evaluated using a Shack-Hartmann wavefront sensor.
• Comparisons were made with reconstructed holograms on DMDs, an analog HOE, and a spherical mirror.

Main Results:

• The digital HOE functioned as a spherical mirror but exhibited astigmatism, similar to DMD holograms.
• Focusability of the digital HOE was inferior to the analog HOE and spherical mirror.
• Phase maps provided clearer visualization of wavefront distortions than Zernike polynomials, revealing greater distortion in the digital HOE.

Conclusions:

• Digital HOEs can replicate spherical mirror functionality but require further optimization to overcome aberrations like astigmatism.
• Wavefront phase mapping is a valuable tool for detailed analysis of HOE performance.
• Current digital HOE technology shows limitations in focusability and wavefront fidelity compared to established optical components.