Design and Diffraction Efficiency Analysis of Field-of-View Deflectors Using Self-Achromatic Grism

Field-deflection optical elements play a significant role in various high-resolution and field-of-view (FOV) expandable optical systems. In our previous work, we proposed a self-achromatic double-faced grism (DFG) configuration capable of field deflection. In this paper, to effectively guide the design and fabrication of DFG diffractive microstructures, we analyze the diffraction process of light within the DFG based on scalar diffraction theory, establish a diffraction efficiency model for the DFG, and propose an optimization method to improve diffraction efficiency over all FOVs while minimizing diffraction efficiency variations across the waveband. Following this design approach, two DFGs for 3–5 μm were specifically designed: one for a 4.4° FOV with 1.6° deflection, and the other for a 40° FOV with 15° deflection. Further optimization increased the bandwidth-integrated average diffraction efficiency (BIADE) to above 0.93 and reduced the diffraction efficiency variations across the waveband by 23.5% and 48%. And based on a tolerance analysis model, we performed tolerance analysis of the designed DFGs. The BIADE of both elements across all FOVs can exceed 0.86 after adding fabrication errors, maintaining a high diffraction efficiency. The results demonstrate that this method can effectively guide the design and manufacturing of diffractive microstructures.