Optical designs for zero order reduction

Abstract

Apparatus for projecting a pattern includes a first diffractive optical element (DOE) configured to diffract an input beam so as to generate a first diffraction pattern on a first region of a surface, the first diffraction pattern including a zero order beam. A second DOE is configured to diffract the zero order beam so as to generate a second diffraction pattern on a second region of the surface such that the first and the second regions together at least partially cover the surface.

Description

RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Patent Application 61 / 022,482, titled “Optical Designs for Zero-Order Reduction,” filed Jan. 21, 2008, which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to optical pattern generation, and specifically to optical pattern generation with reduced uncontrolled zero order energy, particularly (but not exclusively) in configurations using diffractive optical elements.BACKGROUND OF THE INVENTION[0003]Efficient optical projection of patterns is used in diverse applications such as optical three dimensional (3D) mapping. Such a mapping generates a 3D profile of the surface of an object by processing its optical image. The desired properties of the projected patterns generally depend on the application, but typically include high contrast, high projection efficiency and high uniformity of intensity distribution between the projected beamlets that make up...

AI Technical Summary

Benefits of technology

[0009]In an embodiment of the present invention, a first diffractive optical element (DOE) is positioned in proximity to a second DOE. The first DOE diffracts an input beam incident to generate a first diffraction pattern, which comprises a zero order beam. The second DOE receives the zero order beam, and forms a second diffraction pattern therefrom. The two diffraction patterns project into a volume, so that for a given surface within the volume, the first and second diffraction patterns cover respective first and second regions of the surface. Typically, the two regions effectively tile the surface, although there may be relatively minor gaps and / or overlaps between the regions.

[0013]Consequently, diffraction patterns produced by distributed designs of the present invention typically have enhanced overall efficiency compared to the efficiency of generation of the diffraction patterns with a single DOE. In addition, in some embodiments, which are described in detail hereinbelow, contrasts of the beams produced by a distributed design system are typically greater than that of a single DOE, because of the smaller deviation angles required by the two DOEs.

Problems solved by technology

Poor uniformity of a projection method may render it unusable for certain applications, such as those applications in which the projected pattern can be seen by the user.

However, the DOEs may suffer from the so-called zero order problem.

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