中国科学院南京天文光学技术研究所机构知识库

Traditional apochromatic refracting telescopes only achieve spherical aberration  correction at a single wavelength and exhibit significant wavelength-dependent  spherical aberration (spherochromatism), which severely constrains their broad band imaging performance in high-precision astrometric applications and wide-field  surveys. We propose a dual-correction strategy integrating chromatic aberration  equalization and aspheric compensation, achieving diffraction-limited imaging sig nificantly better than the traditional apochromat. Specifically, a 6-in. triplet refractor  designed using this method achieves an on-axis Strehl ratio greater than 99%  across the spectral range from the g-line to the r -line, whereas the 6-in. quadruplet  refractor achieves an on-axis Strehl ratio greater than 99.95% from the ultraviolet  i-line to the near-infrared t -line. Astrometric accuracy simulation shows that this  design enables sub-pixel centroiding (<15 mas) for 16th-magnitude stars. The  designs support the application of wide-field (with short focal length) and multiband  solar observation and can also eliminate manufacturing error accumulation caused  by wavelength mismatch between testing and operational bands in conventional  designs.