I. OPTICAL QUALITY Flatness of the replica surface is held to within 1/4 wavelength, but surface flatness to better than 1/4 wavelength is available on request; First order Rowland ghost intensity is approximately .002% or less; Resolution of all gratings is 80% to 90% of theoretical; and Efficiency at first order Littrow blaze is between 65 to 90%. 2. BLANK MATERIAL Blank material is fine, annealed Pyrex unless otherwise requested. 3. TOLERANCES Blaze wavelength is ± 10% Length and width of blank is ± 0.2 mm Diameter of blank is ± 0.2 mm Thickness of blank is ± 0.5 mm Radius of curvature of concave gratings is ± 0.1% Epoxy surfaces of replica gratings will withstand a maximum temperature of 45º C, but on special request, epoxy surfaces with temperature tolerances of 85º C can be provided. Test information regarding any specific DPI grating is available on request. 4. THIN FILM REPLICA GRATINGS Thin film replica gratings made from polymethylmethacrylate plastic, approximately .002 mm thick are available for use in making polarizers for the infrared. These thick film replicas are available at 1/4 of the standard plane reflectance grating price. Epoxy thin film reflectance gratings also are available. 5. SPECIAL RULINGS Gratings with the following special characteristics can be ruled. Prices on these gratings will be quoted on request: Gratings other than those listed in the tables can be ruled with sizes up to 203 mm x 380 mm. Gratings with spacings other than those listedin the catalogue. Course, low blaze angle gratings Large grids for ion-etched gratings Compound, interlaced gratings Ruled areas other than traditional shapes: round or elliptical, for example Cylindrical, toroidal, or ellipsoidal gratings Radial Gratings Slits Cut-groove, rather than burnished-groove gratings Variable-spaced grooves Variable-depth grooves Variable-angle grooves

6. care of gratings The grating surface can be easily damaged. Handle gratings with extreme care. Never allow anything to touch the grating surface. The grating should be kept in a dust and oil free environment for greatest efficiency. Before proceeding to clean a grating, please contact DPI. DPI will solvent clean gratings upon request for $60.00 each. 7. ORDERING INFORMATION Orders should be addressed to: DIFFRACTION PRODUCTS, INC. P.O. BOX 1030 WOODSTOCK,IL 60098(U.S.A.) Telephone: (815) 338-6768 Cable Address: DPINC, Woodstock, IL 60098 Fax: (815) 338-7167 EMAIL: DPINC@AOL.COM 8. PRICES AND DELIVERY Prices shown including packaging, F.O.B. Woodstock, IL Prices of special gratings are quoted on request. OEM bulk prices are quoted on request. Special Discounts are available where quantities are involved. Delivery on stock gratings is two or three weeks, depending on size and quantity. Delivery time on special order gratings is scheduled at time of order. Every invoice is due and payable in full 30 days from the date of invoice, unless other terms are arranged with DPI.