中国科学院南京天文光学技术研究所机构知识库

The Large Sky Area Multi-Object Fiber Spectroscopy Telescope(LAMOST)has demonstrated exceptional capability in optical spectroscopic surveys.To overcome its inherent limitations in observing late-type stars and regions of high extinction,we present the optical design of a near-infrared(NIR)spectrograph prototype.This instrument is designed to expand LAMOST’s spectral coverage into the J band,specifically targeting 900–1400 nm.Driven by key science goals—precise parameter determination for late-type stars and chemical abundance analysis of red supergiants—the
design specifications require a spectral resolution R�1500,a throughput exceeding 35%,and a multiplexing
capability of 100 fibers.Confronted with constraints on large-format NIR detector availability,the design employs a 2×2 mosaic detector configuration.This necessitates three complementary observing modes,achieved through synchronized rotations of a volume phase holographic grating and the entire NIR optomechanical module, to seamlessly cover the required wavelength range.A critical innovation is the adoption of a fast(F/1.3),fully refractive camera,which avoids the central obscuration of a Schmidt design,thereby enhancing throughput.Optical performance analysis demonstrates that the design meets all requirements:it accommodates 106 fibers,achieves a resolution of 1400–2300(with a two-thirds slit width),and provides a theoretical peak throughput of 65%.This spectrograph prototype will effectively extend LAMOST’s discovery potential into the NIR,enabling groundbreaking studies of Galactic structure and the chemical evolution of nearby galaxies.