Patent EP0840159A2 successfully refreshed from Google Patents.
EP0840159A2
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EP
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Image forming apparatus
Assignee: Risø National Laboratory
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Filing: 1997-11-03
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Granted: —
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Expires: 2017-11-03
Abstract
Abstract An image H(x, y) for displaying a target image G(x, y) is displayed on a liquid-crystal display panel and illumination light from an illumination light source is made to pass therethrough to form an image on a PALSLM. Read light hv is radiated to the PALSLM and a phase-modulated light image α(x, y) read out of the PALSLM is subjected to Fourier transform by a lens. A phase contrast filter gives a predetermined phase shift to only the zero-order light component of Fourier light image α f (x, y). The phase-shifted light image is subjected to inverse Fourier transform by a lens to project an output image O(x, y) to an output plane. A light image O'(x, y) branched by a beam sampler is picked up by a pickup device and an evaluation value calculating unit evaluates conformity between the image O(x, y) and the image G(x, y). A control unit performs feedback control of optical characteristics of the illumination light source, PALSLM, and phase contrast filter, based on the evaluation result.
Inventors
- 👤 Haruyoshi Toyoda
- 👤 Jesper Gluckstad
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:42
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; G02B27/50; G02B27/52; G06; G06E; G06E3/00; G06E3/001; G06E3/005; G03; G03H; G03H2225/00; G03H2225/20; G03H2225/25; G03H2225/30; G03H2225/32
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
235 words
An image forming apparatus for forming a two-dimensional
optical image, based on electric image
information, comprising: an operation optical system, said operation
optical system having at least a light transmission type display device for,
based on said electric image information, displaying a
two-dimensional input image corresponding thereto, an illumination device for radiating illumination
light to the display image on said display device, read light generating means for emitting coherent
read light, optical address type two-dimensional spatial light
modulating means irradiated by a two-dimensional
intensity light image formed according to said two-dimensional
input image by said illumination light
transmitted by said display device, said spatial light
modulating means phase-modulating the read light
radiated from said read light generating means
according to a spatial light intensity distribution of
the two-dimensional intensity light image to output a
two-dimensional phase-modulated light image having a
spatial light intensity distribution, a Fourier lens for converting said phase-modulated
light image to a Fourier light image, a phase contrast filter, provided on a Fourier
plane of said Fourier lens, for phase-shifting a zero-order
light component of said Fourier light image, and an inverse Fourier lens for undergoing inverse
Fourier transform of said Fourier light image to output
said optical image; and operation controlling means for applying a desired
ideal image to be formed as said optical image to a
theoretical characteristic of said operation optical
system, thereby reversely calculating said electric
image information.
Claim 2
Dependent Claim
205 words
An image forming apparatus for forming a two-dimensional
optical image, based on electric image
information, comprising: an operation optical system, said operation
optical system having at least a self-emission type display device for, based on
said electric image information, radiating a two-dimensional
intensity image corresponding thereto, read light generating means for emitting coherent
read light, an optical address type two-dimensional spatial
light modulator irradiated by the two-dimensional
intensity light image produced by said display device,
said spatial light modulator phase-modulating the read
light radiated from said read light generating means
according to a spatial light intensity distribution of
the two-dimensional intensity light image to output a
phase-modulated light image having a spatial light
intensity distribution, a Fourier lens for converting said phase-modulated
light image to a Fourier light image, a phase contrast filter, provided on a Fourier
plane of said Fourier lens, for phase-shifting a zero-order
light component of said Fourier light image, and an inverse Fourier lens for undergoing inverse
Fourier transform of said Fourier light image to output
said optical image; and operation controlling means for applying a desired
ideal image to be formed as said optical image to a
theoretical characteristic of said operation optical
system, thereby reversely calculating said image
information.
Claim 3
Dependent Claim
160 words
An image forming apparatus for forming an
optical image, based on electric image information,
comprising: an operation optical system, said operation
optical system having at least read light generating means for emitting coherent
read light, an electrical address type two-dimensional spatial
light modulator for phase-modulating said read light
according to said electric image information to output
a two-dimensional phase-modulated light image having a
spatial light intensity distribution, a Fourier lens for undergoing Fourier transform of
said phase-modulated light image to a Fourier light
image, a phase contrast filter, provided on a Fourier
plane of said Fourier lens, for phase-shifting a zero-order
light component of said Fourier light image, and an inverse Fourier lens for undergoing inverse
Fourier transform of said Fourier light image to output
said optical image; and operation controlling means for applying a desired
ideal image to be formed as said optical image to a
theoretical characteristic of said operation optical
system, thereby reversely calculating said image
information.
Claim 4
Dependent Claim
19 words
An image forming apparatus according to Claim
3, wherein said two-dimensional spatial light modulator
is a liquid-crystal display panel.
Claim 5
Dependent Claim
24 words
An image forming apparatus according to Claims
1 to 3, wherein said Fourier lens and inverse Fourier
lens are lenses for two-dimensional Fourier transform.
Claim 6
Dependent Claim
60 words
An image forming apparatus according to Claims
1 to 3, wherein said Fourier lens is a first lens for
one-dimensional Fourier transform, said inverse Fourier
lens is a second lens for one-dimensional inverse
Fourier transform, and a Fourier transform plane of
said first lens and an inverse Fourier transform plane
of said second lens are arranged in a same orientation.
Claim 7
Dependent Claim
28 words
An image forming apparatus according to Claim
6, wherein a third lens having the same optical
characteristics as said first lens is positioned
perpendicular to said first lens.
Claim 8
Dependent Claim
26 words
An image forming apparatus according to Claims
1 to 3, wherein said phase contrast filter is a
transmission type filter for transmitting said Fourier
light image.
Claim 9
Dependent Claim
26 words
An image forming apparatus according to Claim 1
to 3, wherein said phase contrast filter is a
reflection type filter for reflecting said Fourier
light image.
Claim 10
Dependent Claim
129 words
An image forming apparatus according to Claims
1 to 3, wherein said phase contrast filter has such
structure that a dielectric multilayer film having a
predetermined light transmittance is interposed between
a light modulating material layer biased at a
predetermined voltage and a photoconductor layer and
that said Fourier light image is made incident to said
light modulating material layer and is reflected by the
dielectric multilayer film to be outputted, and
wherein a part of the zero-order light component
of said Fourier light image transmitted by said
dielectric multilayer film changes an electric
characteristic of said photoconductor layer, thereby
changing a birefringence distribution of said light
modulating material layer, and said light modulating
material layer phase-shifts and outputs said Fourier
light image reflected by the dielectric multilayer
film.
Claim 11
Dependent Claim
71 words
An image forming apparatus according to
Claims 1 to 3, wherein said operation controlling means
comprises: evaluation value calculating means for observing
the optical image outputted from said inverse Fourier
lens to evaluate conformity between said optical image
and said desired ideal image, and variable control means for variably controlling an
optical characteristic of said operation optical
system, based on a result of said evaluation by said
evaluation value calculating means.
Claim 12
Dependent Claim
153 words
An image forming apparatus comprising: optical generation means for generating an
optical signal representative of a first spatial
light distribution in the time plane; first transformation means for transforming
said optical signal into a transformed optical
signal representative of said first spatial light
distribution in the frequency plane; phase shifting means for shifting the phase of
said transformed optical signal by a phase value
within a frequency range of said transformed optical
signal; second transformation means for retransforming
said phase-shifted optical signal into a
retransformed optical signal representative of a
second spatial light distribution in the time plane; storage means for storing an optical signal
corresponding to an image to be formed by the image
forming apparatus; comparison means for comparing said stored
optical signal with said retransformed optical
signal; and correction means for correcting at least one of
said first spatial light distribution and said phase
value in accordance with said comparison.
Claim 13
Independent Claim
122 words
A method of forming an image, the method
comprising: generating an optical signal representative of
a first spatial light distribution in the time
plane; transforming said optical signal into a
transformed optical signal representative of said
spatial light distribution in the frequency plane; shifting the phase of said transformed optical
signal by a phase value within a frequency range of
said transformed optical signal; retransforming said phase-shifted optical
signal into a retransformed optical signal
representative of a second spatial light
distribution in the time plane; and correcting at least one of said first spatial
light distribution and said phase value in
accordance with a comparison between said
retransformed optical signal and a stored optical
signal representative of the image to be formed.
References Cited (Backward Citations)
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