IMAGE DISPLAY SYSTEM
In an image display system, a light distribution forming lens is placed between a laser light source and a spatial light modulator or a MEMS mirror device for adjusting a distribution of light intensity of the laser light so that light intensity at an exit pupil of a projection lens is greater in a radially intermediate part thereof than in a central part thereof. The light distribution lens is provided with a conical incident surface and a convex exit surface so as to function also as a collimator lens. Thereby, the image display system can be constructed as a highly compact unit that is highly efficient in the use of available light and free from the problem of speckle noises.
1 . An image display system, comprising:
a laser light source configured to emit laser light;
a spatial light modulator for generating video light by modulating the laser light according to a given video signal;
a projection lens for projecting the video light onto a screen; and
a light distribution forming lens placed between the laser light source and the spatial light modulator for adjusting a distribution of light intensity of the laser light so that light intensity at an exit pupil of the projection lens is greater in a radially intermediate part thereof than in a central part thereof.
2 . The image display system according to claim 1 , further comprising a fly eye lens placed between the light distribution forming lens and the spatial light modulator for evenly illuminating the spatial light modulator with the laser light, the spatial light modulator causing a greater intensity of the laser light in a radially intermediate part than in a central part at the fly eye lens.
3 . The image display system according to claim 2 , wherein the laser light made incident to the fly eye lens has a peak light intensity at a prescribed distance from an optical center line at an incident surface of the fly eye lens.
4 . The image display system according to claim 3 , wherein the laser light made incident to the fly eye lens has a substantially constant intensity at the prescribed distance from the optical center line at the incident surface of the fly eye lens substantially over an entire circumference.
5 . The image display system according to claim 3 , wherein the light intensity diminishes as one moves radially inward from a region of the peak light density, and moves radially outward from the region of the peak light density.
6 . The image display system according to claim 1 , wherein the system comprises a plurality of laser light sources for different colors, a light distribution forming lens provided for each laser light source, and a cross prism configured to combine laser light exiting the light distribution forming lenses.
7 . The image display system according to claim 1 , wherein the light distribution forming lens is provided with a conical surface on at least one of the incident and exiting surfaces.
8 . The image display system according to claim 7 , wherein the light distribution forming lens is provided with a conical surface facing the laser light source and a convex surface facing the spatial light modulator.
9 . The image display system according to claim 8 , wherein the conical surface is defined as a concave conical surface.
10 . The image display system according to claim 8 , wherein the light distribution forming lens is provided with an aspheric convex lens facing away from the conical surface.
11 . The image display system according to claim 7 , wherein the light distribution forming lens is configured to convert the laser light into a parallel beam.
12 . An image display system, comprising:
a laser light source for emitting laser light;
a MEMS minor device for generating video light by modulating the laser light;
a projection lens for projecting the video light onto a screen; and
a light distribution forming lens placed between the laser light source and the MEMS mirror device for adjusting a distribution of light intensity of the laser light such that an intensity in a radially intermediate region of the laser light is greater than that in a radially central region of the laser light at a beam waist of the laser light.
13 . The image display system according to claim 12 , wherein the laser light at the beam waist has a peak light intensity at a prescribed distance from an optical center line.
14 . The image display system according to claim 13 , wherein the laser light at the beam waist has a substantially constant intensity at the prescribed distance from the optical center line substantially over an entire circumference.
15 . The image display system according to claim 13 , wherein the light intensity diminishes as one moves radially inward from a region of the peak light density, and moves radially outward from the region of the peak light density.
16 . The image display system according to claim 12 , wherein the system comprises a plurality of laser light sources for different colors, a light distribution forming lens provided for each laser light source, and a dichroic mirror device configured to combine laser light exiting the light distribution forming lenses.
17 . The image display system according to claim 12 , wherein the light distribution forming lens is provided with a conical surface on at least one of the incident and exiting surfaces.
18 . The image display system according to claim 17 , wherein the light distribution forming lens is provided with a conical surface facing the laser light source and a convex surface facing the spatial light modulator.
19 . The image display system according to claim 17 , wherein the conical surface is defined as a concave conical surface.
20 . The image display system according to claim 17 , wherein the light distribution forming lens is provided with an aspheric convex lens facing away from the conical surface.