OPTICAL DESIGNS FOR ZERO ORDER REDUCTION
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.
1 . Apparatus for projecting a pattern, comprising:
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 comprising a zero order beam; and
a second DOE 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.
2 . The apparatus according to claim 1 , wherein the second DOE comprises an optically active region configured to receive the zero order beam, and an optically inactive region configured to transmit the first diffraction pattern absent the zero order beam.
3 . The apparatus according to claim 1 , wherein the first and the second DOEs are formed on one optical element.
4 . The apparatus according to claim 1 , wherein the first and the second DOEs are formed on separate optical elements.
5 . The apparatus according to claim 1 , wherein the second diffraction pattern comprises a further zero order beam, and wherein an energy flux of the further zero order beam is less than 0.1% of an energy flux of the input beam.
6 . The apparatus according to claim 1 , wherein the input beam has an input beam wavelength, and wherein the first DOE and the second DOE are configured so that the first and the second regions at least partially cover the surface independently of the input beam wavelength.
7 . The apparatus according to claim 1 , wherein the first diffraction pattern forms a first diffraction image comprising a first set of first spots on the first region, and wherein the second diffraction pattern forms a second diffraction image comprising a second set of second spots on the second region.
8 . The apparatus according to claim 1 , wherein at least one of the first and the second diffraction patterns forms a diffraction image comprising at least one of a set of lines and an area having graduated intensities.
9 . The apparatus according to claim 1 , wherein the first region and the second region tile the surface.
10 . The apparatus according to claim 1 , wherein the first region is bounded by a first rectangle and a second rectangle smaller than the first rectangle, the first and the second rectangles having a common center, and wherein the second region is bounded by the second rectangle.
11 . Apparatus for projecting a pattern, comprising:
a first diffractive optical element (DOE) configured to diffract an input beam so as to generate a plurality of separate output beams; and
a second DOE configured to apply a diffractive effect to the plurality of separate output beams so as to generate a respective plurality of diffraction patterns on respective regions of a surface such that the respective regions together at least partially cover the surface.
12 . The apparatus according to claim 11 , wherein the first and the second DOEs are formed on one optical element.
13 . The apparatus according to claim 11 , wherein the first and the second DOEs are formed on separate optical elements.
14 . The apparatus according to claim 11 , wherein the input beam has an input beam wavelength, and wherein the first DOE and the second DOE are configured so that the respective regions at least partially cover the surface irrespective of the input beam wavelength over a specified wavelength range.
15 . The apparatus according to claim 11 , wherein the plurality of diffraction patterns form a plurality of sets of spots on the respective regions.
16 . The apparatus according to claim 11 , wherein at least one of the diffraction patterns forms a diffraction image comprising at least one of a set of lines and an area having graduated intensities.
17 . The apparatus according to claim 11 , wherein the respective regions tile the surface.
18 . Apparatus for projecting a pattern, comprising:
a diffractive optical element (DOE) configured to diffract an input beam having a wavelength so as to generate a diffraction pattern comprising a zero order beam; and
a narrow-band filter, which is tuned to the wavelength of the input beam and is positioned with respect to the DOE so as to cause the diffraction pattern, absent the zero order beam, to impinge on a region of a surface.
19 . The apparatus according to claim 18 , wherein the filter comprises an interference filter.
20 . The apparatus according to claim 18 , wherein the filter comprises a grating.
21 . A method for projecting a pattern, comprising:
diffracting an input beam with a first diffractive optical element (DOE) so as to generate a first diffraction pattern on a first region of a surface, the first diffraction pattern comprising a zero order beam; and
diffracting the zero order beam with a second DOE 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.
22 . A method for projecting a pattern, comprising:
diffracting an input beam with a first diffractive optical element (DOE) so as to generate a plurality of separate output beams; and
applying a diffractive effect to the plurality of separate output beams with a second DOE so as to generate a respective plurality of diffraction patterns on respective regions of a surface such that the respective regions together at least partially cover the surface.
23 . A method for projecting a pattern, comprising:
diffracting an input beam having a wavelength with a diffractive optical element (DOE) so as to generate a diffraction pattern, which comprises a zero order beam;
positioning a narrow-band filter, which is tuned to the wavelength of the input beam, with respect to the DOE so as to cause the diffraction pattern, absent the zero order beam, to impinge on a region of the surface.