Producing illumination-independent additively mixed colors by diffractive optics.

We apply transmission gratings under Littrow incidence to produce polychromatic colors by additive color mixing. Parametric optimization of gratings is employed to produce high efficiency. In addition, we show that the system can yield the same color from a wide variety of spectra; i.

Diffraction of conic and Gaussian beams by a spiral phase plate.

An analytical expression for the spatial spectrum of the conic wave diffracted by a spiral phase plate (SPP) with arbitrary integer singularity of order n is obtained. Conic wave diffraction by the SPP is equivalent to plane-wave diffraction by a helical axicon. A comparison of the conic wave and Gaussian beam diffraction on a SPP is made.

White LED light coupling into light guides with diffraction gratings.

Radial diffractive gratings are used to couple light of a white LED into a light guide. Theoretical coupling efficiencies are evaluated with rigorous diffraction theory in a pure conical mounting. It is shown that when the refractive index of the grating increases from 1.