Fabrication and testing of chemically micromachined silicon echelle gratings

We have fabricated large, coarsely ruled, echelle patterns on silicon wafers by using photolithography and chemical-etching techniques. The grating patterns consist of 142-microm-wide, V-shaped grooves with an opening angle of 70.6 degrees, blazed at 54.7 degrees. We present a detailed description of our grating-fabrication techniques and the results of extensive testing. We have measured peak diffraction efficiencies of 70% at lambda = 632.8 nm and conclude that the gratings produced by our method are of sufficient quality for use in high-resolution spectrographs in the visible and near IR (lambda approximately = 500-5000 nm).