Patent ID: 7158304

Claim:
An apparatus comprising: a virtually imaged phased array (VIPA) generator receiving an input light at a respective wavelength and producing a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light, the output light thereby being spatially distinguishable from an output light produced for an input light at a different wavelength; a reflecting surface having a cone or modified cone shape, the reflecting surface being movable in a direction perpendicular to a plane which includes the traveling directions of collimated output light from the VIPA generator for input light at different wavelengths; and a lens or mirror focusing the output light traveling from the VIPA generator onto the reflecting surface so that the reflecting surface reflects the output light, the reflected light being directed by said lens or mirror back to the VIPA generator, curvature c(y) of the reflecting surface being as follows: c ⁡ ( y ) = K 8 ⁢ f 4 ⁢ y 4 + K ⁢ ⁢ Θ 2 ⁢ f 3 ⁢ y 3 + K ⁢ ⁢ Θ 2 - ( f - a ) 2 ⁢ f 2 ⁢ y 2 where y=is a light focusing position on the reflecting surface, Θ=is an input angle of the input light to the VIPA generator in air, f=is a focal length of the lens or mirror, a=is a depth of a center beam waist of the VIPA generator, and K is a constant so that chromatic dispersion equals −2n 4 K/cλ, with c being the speed of light, λ being wavelength, and n being a refractive index of material forming the VIPA generator.