EFFECTS OF FABRICATION ERRORS ON THE PERFORMANCE OF CYLINDRICAL DIFFRACTIVE LENSES - RIGOROUS BOUNDARY-ELEMENT METHOD AND SCALAR APPROXIMATION

The effects of fabrication errors on the performance of collimating fi nite-thickness cylindrical diffractive lenses with eight discrete leve ls are investigated with a rigorous boundary-element method and a scal ar approach. The photolithographic fabrication errors considered are m ask alignment errors, exposure errors (that result in linewidth errors ), and etch-depth errors. A cylindrical Gaussian beam of TE or TM pola rization is incident upon the resulting lenses. Lenses of F/4, F/2, an d F/1.4 are examined. The diffraction efficiencies of the lenses with fabrication errors are generally lower than the error-free lenses with the most severe performance degradation occurring for mask misalignme nt and exposure errors. (C) 1998 Optical Society of America. OCIS code s: 050.0050, 050.1940, 050.1970, 120.1680, 350.3950.