Multi-wavelength digital holography based on Kramers-Kronig relations

Area of Science:

• Optics and Photonics
• Metrology
• Digital Holography

Background:

• Traditional angle-multiplexing techniques in multi-wavelength digital holography face limitations in accuracy and resolution.
• Spectral utilization and measurement accuracy are critical challenges in multi-wavelength interference applications.

Purpose of the Study:

• To develop a unified angle-multiplexing multi-wavelength Kramers-Kronig (KK) model for enhanced digital holography.
• To overcome the accuracy and resolution limitations of existing angle-multiplexing methods.
• To improve spectral utilization and measurement accuracy in multi-wavelength interference.

Main Methods:

• Proposed a multi-wavelength digital holography approach based on Kramers-Kronig (KK) relations.
• Developed a unified angle-multiplexing multi-wavelength KK model.
• Captured object light waves using the full effective bandwidth from a single interferogram and reference wave intensity by linking real and imaginary parts of the multi-wavelength complex function via the KK relation.
• Employed a three-wavelength multiplexing system for topography measurement of multi-step samples.

Main Results:

• Expanded the spectral range by more than twice compared to traditional methods.
• Reduced measurement errors by 39.3%.
• Improved peak signal-to-noise ratio and structural similarity index by nearly three times compared to the Fourier transform (FT) method.

Conclusions:

• The proposed KK-based multi-wavelength digital holography method significantly enhances measurement accuracy and resolution.
• This approach offers a novel solution for high-precision multi-wavelength dynamic measurements.
• The method demonstrates potential to overcome existing limitations in multiplexing technology for optical measurements.