Kilometer scale primary objective telescope with no moving parts

摘要

The author proposes the use of a diffraction grating as a primary collector in a very large ground-based telescope. The grating is to be placed at grazing exodus relative to a secondary receiver and will have considerable length relative to width. Collector areas of square kilometers are being considered. Large collectors pose problems for ordinary telescopes, but with the proposed telescope, the rotation of the earth is the only requisite motion. Other than the earth itself, there are no moving parts. In the course of a night's observation, a plurality of stars within a narrow band of right ascension would yield detailed spectra. We anticipate that while acquiring the spectra of a star, the instrument would also acquire the spectra of any planetary system around it, because the high inherent resolving power of the instrument can measure subtle Doppler shifts, and the collecting area is sufficiently large to detect spectra from planets in the full glare of the star that illuminates them. Where signature spectra are available, planets can by typed, including earth-like planets which can be distinguished by their unique spectra and their implied surface temperature as inferred from orbit diameter. Our study investigates several grating arrangements, types and efficiencies including some using reflection gratings and one with a transmission grating in an evanescent mode. We explore options for grating fabrication and mounting.