Richardson Gratings is providing a large mosaic echelle grating for the Extreme Precision Spectrometer (EXPRES), an instrument for the 4.3-m Discovery Channel Telescope outside Flagstaff, Ariz. The telescope is designed to detect Earth-like planets as part of Yale University's 100 Earths Project. Researchers aim to search nearby stars for rocky plants on which liquid water may exist, locating areas suitable for life. The grating was fabricated as a monolithic aluminum-coated replica from two matched gratings on the same echelle master. It has 31.6 grooves per millimeter with a nominal blaze angle of 75°. The peak unpolarized diffraction efficiency meets or exceeds 60 percent for diffracted orders peaking between 400 and 700 nm. Spectral resolving power was measured to exceed 600,000 at 633 nm, with spatial resolution better than 4 arcsec. The overall diffracted wavefront demonstrates irregularity from a plane wavefront of less than 0.1 waves at 633 nm. Founded in 1947, Richardson Gratings designs and manufactures standard and custom diffraction gratings for use in analytical instrumentation, lasers and tunable light sources, fiber-optic telecommunications networks and photolithographic systems, as well as for researchers, astronomers and educators. It is part of Newport Corp.