Optical design of an image slicer for the low-dispersion spectrograph of the Chinese Giant Solar Telescope (CGST)

The Chinese Giant Solar Telescope (CGST) low-dispersion spectrograph requires a large field-of-view (FOV) and high spatial resolution, which can be addressed by a carefully designed image slicer system. Our proposed design divides the rectangular 50ʹʹ × 20ʹʹ FOV at the telescope focal plane into four 50ʹʹ × 5ʹʹ subfields. Each subfield undergoes optical reconstruction using its independent collimator-camera system (F/36–F/25.79), achieving vertical alignment and focal reduction of subfields to form a pseudo-slit. Using tilt mirrors for scanning allows simultaneous acquisition of spectral data with both a large FOV and a high angular resolution of 0.05ʹʹ. This resolves manufacturing challenges for an image slicer, avoiding the requirement for hundreds of elements, multi-angle configurations, and compact dimensions, and also provides effective technical support for engineering work on the CGST.