Dry photopolymer films for computer-generated infrared radiation focusing elements

Area of Science:

• Optics and Photonics
• Materials Science
• Holography

Background:

• Traditional fabrication of diffractive optical elements often involves wet processing, leading to surface scattering.
• Photopolymerizable materials offer potential for dry, holographic recording of relief structures.
• Understanding the mechanism of hologram formation in photopolymers is crucial for optimizing element performance.

Purpose of the Study:

• To develop a dry photopolymer-based fabrication method for relief computer-generated focusing elements for infrared (IR) radiation.
• To investigate the self-development process and surface wave formation in photopolymer layers.
• To achieve high diffraction efficiency for IR radiation using these elements.

Main Methods:

• Utilizing a dry photopolymer recording material for holographic illumination.
• Employing a self-development process in the dark, eliminating wet processing.
• Analyzing dye-sensitized polymerization of acrylamide and its nonlinear effects.
• Implementing corrections to the computer-generated amplitude function to compensate for nonlinearity.

Main Results:

• Successful fabrication of relief computer-generated focusing elements for IR radiation using a dry photopolymer approach.
• Observation of monomer surface wave formation along the light-darkness boundary, confirming a thermodynamic model.
• Achieved a diffraction efficiency of approximately 55% for carbon dioxide (CO2) laser radiation (λ = 10.6 µm).
• Demonstrated low surface scattering in the fabricated diffractive elements.

Conclusions:

• The dry photopolymer fabrication method is effective for producing high-performance IR focusing elements.
• The observed surface wave phenomenon provides new insights into photopolymer hologram formation mechanisms.
• This technology offers a promising route for efficient and low-scattering IR diffractive optics.