Patent ID: 7177031

Claim:
A method of providing a grating array system comprising the step of aligning at least one grating of a plurality of gratings with respect to another providing effectively one large monolithic grating, with said plurality of gratings operative in a coherently additive mode to simultaneously satisfy the following equations OPD L =−OPD P , where OPD L =Δx (λ/ d ), Δ x=L−Md ; and OPD P =2(Δ z )cos θ r , Δz=P−Nλ, (1) wherein OPD is an optical path difference, Δx is a change in a movement in a lateral direction parallel to the plane of the gratings, L is a lateral shift between gratings, M is an integer, d is a grating pitch, λ is a wavelength of light, which is the average wavelength for polychromatic light, Δz is a change in a movement in the piston shift direction perpendicular to the plane of the gratings P is a piston shift between the gratings, N is any integer, and θ r is the rotation of one grating with respect to each other about a line perpendicular to the grating plane Δθ r =−Δθ y * ctgθ i, (2) wherein Δθ r is a change in rotation direction of one grating with respect to the other gratings about a line perpendicular to a grating plane, Δθ y is a change in an angular displacement in the y-direction known as tip, and θ i is an angle of incidence of the incident light beam on the grating array system Δθ x =0, (3) wherein Δθ x is a change in an angular displacement in the x-direction known as tilt.