To reduce the stray light effect of Xing Long 1-meter optical telescope

an objective lens was developed

and simulations and observations were undertaken to evaluate the lens. The Point Source Normalized Irradiance Transmission(PSNIT) for“dome-telescope”and “dome-telescope-lens” systems was calculated with the code Tracepro and observations were carried out at a moon night. The calculation results indicate that for the stray light sources located at off-axis angle within 30°

the PSNITs of the observational system

including dome

1 m telescope and the lens

have been lower than 10

-10

.Furthermore

the observation results for stars located at 22°and 25°off-axis angles away from the moon in May 26th 2008 indicate that the observational SNR of the system has been increased by a factor about 1.4 with the lens. These results show that for the 1-meter optical telescope the stray light is reduced and the photometric accuracy and limiting magnitude are improved by the lens effectively