Fig. 1. Schematic diagram of the holographic exposure system and the process for preparing PMCG

Fig. 2. Frame of SRG system

Fig. 3. SRG system measurement signal. (a) Interference field periodic measurement signal at first holographic exposure; (b) interference field periodic measurement signal at second holographic exposure

Fig. 4. PMCG preparation process. (a) Quartz substrate spin-coated with photoresist; (b) first holographic exposure; (c) substrate after the first holographic exposure; (d) second holographic exposure; (e) prepared PMCG after two holographic exposures

Fig. 5. Schematic diagram of two exposures

Fig. 6. PMCG with size of 30 mm×50 mm×10 mm

Fig. 7. AFM characterization diagrams and grating groove outlines of PMCG under the same envelope with different spans of adjacent grating grooves. (a) The span is 16.43 μm; (b) the span is 16.45 μm; (c) the span is 16.38 μm; (d) the span is 16.40 μm

Fig. 8. Laser beam expanding collimation system and diffraction light field. (a) Schematic diagram of laser beam expanding and collimation system; (b) diffraction light field of PMCG

Fig. 9. Diffraction light field distribution at different positions from the PMCG. (a) Distance of 1 m; (b) distance of 3 m; (c) distance of 5 m; (d) distance of 7 m