METHOD FOR REDUCING SPECKLES AND A LIGHT SOURCE USED IN SAID METHOD
A method of reducing speckle effects in a projected image which is displayed on a display surface, comprising the steps of splitting an incident beam into one reference beam and one modulation beam; modulating said modulation beam with a modulation unit so as to produce a modulated beam; recombining the modulated beam and the reference beam onto a diffuser; and deflecting the recombined beam so as to project said image onto said display surface.
1 . A method for reducing speckle effects in a projected image which is displayed on a display surface, comprising the steps of: splitting an incident beam into one reference beam and one modulation beam;
modulating said modulation beam with a modulation unit so as to produce a modulated beam;
recombining the modulated beam and the reference beam onto a diffuser;
deflecting the recombined beam so as to project said image onto said display surface.
2 . The method of claim 1 , further comprising:
producing a coherent light beam with a coherent light source;
collimating, focusing and/or changing divergence angle(s) of said coherent light beam with a lens so as to produce said incident beam light.
3 . The method of claim 1 , further comprising:
condensing said modulated beam with a condenser lens.
4 . The method of claim 1 , wherein said diffuser comprises a passive diffuser.
5 . The method of claim 1 , wherein said diffuser comprises an active diffuser.
6 . The method of claim 1 , said step of deflecting the recombined beam comprising deflecting said beam with a mems-based digital micromirrors device.
7 . The method of claim 1 , said step of deflecting the recombined beam comprising deflecting said beam with one two-dimensional mems scanning mirror or with two independent one-dimensional scanning mirrors.
8 . The method of claim 1 , said step of deflecting the recombined beam comprising deflecting said beam onto a liquid crystal based device.
9 . The method of claim 1 , said step of modulating comprising deflecting said modulating beam with a rotative device, for example a rotative mirror that oscillates.
10 . The method of claim 1 , said step of modulating comprising deflecting said modulating beam with a vibrating device.
11 . The method of claim 1 , said step of modulating comprising deflecting said modulating beam with an electro-optical device, such as for example an electro-active polymer.
12 . The method of claim 1 , wherein the width of said interference fringes on the display surface is comprised between 10 −6 and 10 −2 m so as to be not or barely perceptible by the human eye.
13 . The method of claim 1 , wherein said incident beam is a RGB beam source.
14 . The method of claim 1 , independently applied to three said incident beams with different wavelengths.
15 . The method of claim 1 , comprising a step of time-modulating said incident beam so as to vary the intensity of the recombined beam that is projected onto different portions of said display surface.
16 . A light source comprising:
a laser source for producing an incident beam a beam-splitter for splitting said incident beam into one reference beam and one modulation beam;
a modulation unit for modulating said modulation beam so as to produce a modulated beam;
a diffuser arranged so that the modulated beam and the reference beam are recombined onto said diffuser;
a deflecting unit for deflecting the recombined beam so as to project a speckle-free image onto a display surface.
17 . The light source of claim 16 , further comprising:
a beam shaper for collimating, focusing and/or changing divergence angle(s) the coherent beam generated by said laser source into said incident beam light.
18 . The light source of claim 16 , further comprising:
a condenser lens for condensing said modulated beam.
19 . The light source of claim 16 , said diffuser comprising a passive diffuser.
20 . The light source of claim 16 , said diffuser comprising an active diffuser.
21 . The light source of claim 16 , said deflecting unit comprising a mems-based digital micromirror device.
22 . The light source of claim 16 , said deflecting unit comprising one two-dimensional mems scanning mirror or two independent one-dimensional scanning mirrors.
23 . The light source of claim 16 , said deflecting unit comprising a liquid crystal based device.
24 . The light source of claim 16 , said modulation unit comprising a rotative device, for example an oscillating rotative mirror.
25 . The light source of claim 16 , said modulation unit comprising a vibrating device.
26 . The light source of claim 16 , said modulation unit comprising an electro-optical device.
27 . The light source of claim 16 , arranged for producing interference fringes on a display surface with a width comprised between 10 −6 and 10 −2 m so as to be not or barely perceptible by the human eye.
28 . The light source of claim 16 , said laser source being a RGB beam source.
29 . The light source of claim 16 , said laser source being time-modulated so as to vary the intensity of the recombined beam.
30 . A device comprising the light sources according to claim 17 , each light source having a different wavelength.