Naval Research Laboratory, 4555 Overlook Ave. S.W. WASHINGTON,D.C. 20375

58 -- DIFFRACTION GRATING SOL N00173-97-Q-0030 POC Darlene Copp, Purchasing Agent, (202) 767-2374 Fax (202) 404-8158. Naval Research Laboratory has a requirement for four (4) holographically recorded, ion-etched gratings. The grooves shall have a laminar (rectangular) profile, and run parallel to the long edge of each 90 x 160 mm grating. The grooves shall have a nominal density of 3600 1/mm and should be formed on a spherical face with a nominal radius of curvature of 4000 mm. The groove depth should be optimised to yield zero-order suppression and maximum first-order diffration efficiency at a wavelength of 231 Angstrom, using an angle of incidence of 4.85 degrees and an angle of diffraction of zero degrees. The grating blanks should be of fused silica, Herasil I, and each should have a dimensions of 160 x 90 x 20 mm. The dimensional tolerance should be +/- 0.1 mm. The blanks should be ground and polished to achieve radius of curvature of 4000+/- 5 mm. The process should be designed to minimize the deviation among the four radii. The slope error (FWRMS) is less than 0.2 arc sec in the longitudinal direction and lessthan 0.3 arc sec in the transverse direction. The micro roughness of the spherical surface should be less tham 0.5 nm (RMS), with a design goal of 0.3 nm (RMS). The rear face should be flat and polished to a finish sufficient for autocollimation, and its normal and the principal axis of the sperical surface should be parallel, with a tolerance of +/- 1 arc min. The side faces should also be flat and polished to a finish suitable for autocollimation. One side face, preferably that closest to the 1 cm wide allignment grating strip (as will be stated below) should be paralle to the groove direction, with a tolerance of +/- 1 arc min. A marking should identify this side face. All edges have a 2 mm wide 45 degree bevel. The holographic recording should use two monochromatic plane wave beams ( wavelength 488 nm) having equal and opposite angles of incidence to the grating principle axis. The resulting grooves should be parallel and of uniform density when projected on to the plane whose normal is the principal axis. The grooves should be aligned with the long side of the grating, with a tolerance of +/- 100 arc sec. The groove density at the grating center is 3600 +/-1 1/mm, and the variation in ruling density over the grating is less than 1 part in 100,000. The grooves formed by the ion-etching process shoul have a depth of 5.8+/-0.5 nm, and the width of the land and the groove is 139+/-15 nm. The microroughness within the grooves is less than 0.5 nm (RMS), with a design goal of 0.3 nm (RMS). For the purpose of alignment using optical light (green Hg line at 5460.740 Angstrom), grooves with a density of 152.3+/-1.0 1/mm should be formed on a strip 10 mm wide on one long edge of the grating, so that the high density grating surface is 160 x 80 mm. The low-density and high-density grooves should be parallel, with a tolerance of +/-2 arc min. the grooves should have a depth of 139+/-14 nm, and the width of the land and the groove should be 3200+/-300 nm. Each grating should be stored and shipped in its own clean, hermetically seal aluminum alloy container. It should be locked in position by Teflon clamps which prevent any contact between the grating and container surfaces. Documentation should be provided which summarizes the results of test made during manufacture to establish the blank geometry, the characteristics of the polished surfaces, the groove density and directionn, and the geometry and microroughness of the final groove profile at a number of positions on the grating. Oral request will not be accepted. (0024)

Loren Data Corp. http://www.ld.com (SYN# 0308 19970129\58-0001.SOL)