Patent ID: 7050235

Claim:
A method for providing a diffractive optical filter having a far field discrete spectral response C[m] which is a scaled approximation to a Hermitian, passive discrete spectral response B[m], the method comprising: a) calculating t[j] such that t[j] and B[m] are a discrete Fourier transform pair; b) calculating t min equal to the minimum of t[j]; c) calculating u[j]=t[j]−t min ; d) calculating D equal to the sum of u[j] for all j; e) calculating v[j]=u[j]/D; f) setting a discrete fractional level density of said diffractive optical filter substantially equal to v[j]; whereby C[m]=1 for m=0, and C[m]=B[m]/D for nonzero m, thereby providing said scaled approximation to B[m].