Computer graphics processing and selective visual display system – Plural physical display element control system – Optical means interposed in viewing path
Reexamination Certificate
1999-03-24
2003-04-01
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Optical means interposed in viewing path
C359S015000, C349S025000
Reexamination Certificate
active
06542134
ABSTRACT:
BACKGROUND
The invention generally relates to projection systems, and more particularly, the invention relates to a projection system that includes a holographic beam splitter.
An ever-increasing number of applications are using display devices that are derived from a combination of liquid crystal optics technology and semiconductor technology. For example, these display devices may be used in mobile telephones, projection systems, home entertainment systems and monitors for personal computers.
One such display device is a spatial light modulator (SLM) that may be used in a projection system to form a modulated beam image. For color projection systems, the system may have one SLM for each primary color channel (red, green and blue (RGB) primary color channels, as examples) of the projection system. As an example, to form a projected multicolor image, one SLM may modulate a red beam (of the red channel) to form a red modulated beam image, one SLM may modulate a green beam (of the green channel) to form a green modulated beam image, and another SLM may modulate a blue beam (of the blue channel) to form a blue modulated beam image. In this manner, the red, green and blue modulated beam images combine on a projection screen to form the multicolor image.
Conventional projection systems may include optics to keep the beams of the different color channels separated. For example, referring to
FIG. 1
, a conventional reflective projection system
10
may include a light source
28
that generates a beam of white light. For purposes of separating the beam of white light into its primary red, green and blue beams (of the different color channels), the projection system
10
may include dichroic beam splitters
12
and
16
. In this manner, the dichroic beam splitter
12
may separate a red beam, for example, from the white beam of light. A mirror
13
may reflect the red beam to a polarizing beam splitter
19
that, in turn, reflects the red beam to a reflective SLM
14
that modulates the red beam. The polarizing beam splitter
19
directs the resultant green modulated beam of light to an X-cube prism
24
that directs the modulated beam through projection optics
26
to form one component of the multicolor image, the green modulated beam image, on a projection screen (not shown). The projection system
10
typically includes additional optical devices, such as the dichroic beam splitter
16
, and polarizing beam splitters
17
and
22
to direct the unmodulated green and blue beams (from the original white beam) to an SLM
18
and an SLM
20
, respectively. The polarizing beam splitters
17
and
22
and the X-cube prism
24
direct the resultant green and blue modulated images through the projection optics
26
to form the remaining components of the multicolor image.
An example of a more compact conventional projection system
30
is depicted in FIG.
2
. The projection system
30
uses a folded optics system that is formed from prism blocks
32
,
34
and
36
. In this manner, a light source
46
generates a white beam of light that is directed via a polarizing beam splitter
44
toward the prism blocks
32
,
34
and
36
. Dichroic optical coatings
35
and
41
may be used on some of the prism block faces to maintain the separation of the different color channels and to divide the white beam of light into the its primary red, green and blue beams. In this manner, the dichroic optical coatings
35
and
41
direct the red, green and blue beams of light to an SLM
38
, SLM
40
and SLM
42
, respectively. Once modulated, the modulated beams of light follow optical paths near (but in the reverse order) to the paths followed by the associated unmodulated incident beams of light to return to the polarizing beam splitter
44
. The polarizing beam splitter
44
, in turn, directs the modulated beams through projection optics
48
to form a multicolor image on a projection screen (not shown).
Unfortunately, the dichroic beam splitters may be quite expensive, and the filtering by the dichroic beam splitters may remove a large amount of light. Furthermore, the dichroic beam splitters are one of a number of optical devices that may make alignment of the modulated beam images cumbersome during calibration of the system
10
,
30
and may introduce a significant amount of light loss due to the large number of reflective surfaces.
Thus, there is a continuing need for a system that addresses one or more of the problems stated above.
SUMMARY
In one embodiment of the invention, a projection system includes at least one light source, at least one light modulator and a holographic beam splitter. The holographic beam splitter is adapted to establish optical communication between the light source(s) and the light modulator(s).
In another embodiment, a projection system includes at least one light source, at least one light modulator and a holographic beam splitter. The light source(s) are adapted to furnish unmodulated beams of light, and each unmodulated beam of light is associated with a different color channel. Each light modulator is associated with a different one of the unmodulated beams of light and is adapted to modulate the associated unmodulated beam of light to produce a modulated beam of light. The holographic beam splitter is adapted to direct each of the unmodulated beams of light to the associated light modulator.
In another embodiment, a method includes furnishing reference waves of light and recording interference patterns. Each reference wave of light is associated with a different color channel, and each of the interference patterns is associated with a different one of the reference waves of light. The interference patterns are used to produce object waves of light, and each of the object waves is associated with a different one of the color channels. The object waves are modulated to produce modulated light waves.
In yet another embodiment, a beam splitter includes a holographic medium that is adapted to receive beams of light that are associated with different color channels. The medium is adapted to direct the beams of light along optical paths that are situated at different angles based on the associated color channels.
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patent: WO 97/13175 (1997-04-01), None
Patent Abstracts of Japan, Publication No. 09197340 (Jul. 31, 1997).
Patent Abstracts of Japan, Publication No. 10312034 (Nov. 24, 1998).
Intel Corporation
Osorio Ricardo
Shalwala Bipin
Trop Pruner & Hu P.C.
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