A concept design of deployable space membrane diffractive telescope

Abstract

The traditional Space Telescope has a tremendous potential shortcoming for very large aperture space telescopes. The total mass of the conventional monolithic mirror will skyrocket along with the increase of the apertures; even so much as cannot be launched to space even with the best current lightweight mirror designs. The use of a membrane diffractive optical element (DOE) can reduce the mass of large space telescopes and achieve as much as a factor of seven in mass savings per unit aperture area compared to lightweight mirrors. The primary lens of this telescope is a transmissive membrane etched with a diffraction pattern that offers a significant relaxation in the control requirements on the membrane surface figure. In 2012, the meter-scale transmissive membrane DOE was successfully developed. In 2014, the brassboard telescope of 5-meter diameter successfully demonstrates the ability to collect polychromatic high resolution imagery over a representative object using the transmissive DOE technology. All in all, the development of diffractive telescope with apertures in excess of 5 meter diameter has been put on the agenda. In this paper we first discuss the diffractive imaging system. Then some traditional deployable space optical systems are analyzed in the aspects of deployment methods and characteristics and a conceptual design for a 10m-diameter diffraction telescope is proposed. At last we talk about the key technologies for membrane diffractive telescope.