研究目的
To propose and test a new approach for fabricating diamond diffractive optical elements (DOEs) with continuous relief for powerful CO2 lasers, avoiding direct laser processing of polycrystalline diamond by using short-pulse laser ablation to create inverted surface microstructures on a silicon substrate for replication onto diamond surface within the CVD process.
研究成果
The study demonstrates a promising alternative for direct laser micromachining of polished polycrystalline diamond in fabrication of variable DOEs with high diffraction efficiency for powerful CO2 lasers. The fabricated DOEs showed high transparency and diffraction efficiency, with low radiation scattering. The technique allows for the fabrication of complex continuous relief structures that are difficult to achieve with photolithography.
研究不足
The main limitation is the surface roughness of the laser-structured silicon template, which affects the final roughness of the diamond replica. The replication process also introduces slight surface roughening and occasional micro-craters.
1：Experimental Design and Method Selection:
The study involves short-pulse laser microstructuring of a silicon wafer, used as a substrate for polycrystalline diamond growth in a microwave plasma-assisted CVD process. After polishing, the silicon substrate is removed via chemical etching.
2：Sample Selection and Data Sources:
A 3 mm thick and 57 mm in diameter polycrystalline silicon wafer was used to prepare microstructured patterns for diamond replication.
3：List of Experimental Equipment and Materials:
A multimode laser system (VaryDisk50 from Dausinger+Giesen GmbH), XY scanner (Miniscan II from Raylase), F-Theta lens (F=100 mm), microwave plasma CVD system (ARDIS-100 from Optosystems Ltd), Raman spectrometer (LabRAM HR-800 from HORIBA-Jobin Yvon), white-light interferometer (ZYGO NewView5000), scanning electron microscope (JSM-6510LV from JEOL Ltd., Japan), IR spectrometer (Perkin Elmer Spectrum 100).
4：0).
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Laser micromachining of the silicon surface was performed with optimized processing parameters. The silicon templates were seeded with nanodiamond particles, and a polycrystalline diamond film was deposited. The diamond film was polished, and the silicon substrate was removed chemically.
5：Data Analysis Methods:
The surface profile of the diamond elements was investigated with a white-light interferometer and a scanning electron microscope. Transmittance spectra were measured by an IR spectrometer. Optical performance was evaluated using a TEA CO2 laser.
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