EP0271900A2
Expired / Lapsed
EP
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Device, method and apparatus for optical modulation
Assignee: Canon Inc
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Filing: 1987-12-16
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Granted: —
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Expires: 2007-12-16
Abstract
Abstract An optical recording method comprises writing in a ferroelectric material heated at or above the glass transition point, and holding the resultant written state below the glass transition point. Preferably, the ferroelectric material constituting the optical recording layer has an optical thickness capable of providing a multiple reflection state. The multiple reflection state of the optical recording layer is locally changed at or above the glass transition point by irradiating the optical recording layer under an electric field with a laser beam in order to write in the optical recording layer.
Inventors
- 👤 Kazuo Yoshinaga
- 👤 Takeshi Miyazaki
- 👤 Toshikazu Ohnishi
- 👤 Yutaka Kurabayashi
- 👤 Yoshio Takasu
- 👤 Tadashi Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 23:43
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/004; G11B7/0055; G11B7/00557; C; C09; C09K; C09K19/00; C09K19/04; C09K19/38; C09K19/3833; C09K19/3842; C09K19/3852; C09K19/3857; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/133365; G02F1/137; G02F1/139; G02F1/141; G11B7/24; G11B7/241; G11B7/242; G11B7/244; G11B7/25; G11B9/00; G11B9/02
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
32 words
An optical modulation method, comprising: writing in a ferroelectric having a glass transition point at or above the glass transition point, and holding the resultant written state below the glass transition point.
Claim 2
Dependent Claim
32 words
An optical modulation method, comprising: writing in a ferroelectric having a glass transition point at or above the glass transition point, and holding the resultant written state below the glass transition point.
Claim 3
Dependent Claim
20 words
A method according to Claim 1, wherein the written state is given by a change in birefringence of the ferroelectric.
Claim 4
Dependent Claim
33 words
A method according to Claim 1, wherein the writing in the ferroelectric is effected by applying an electric field to the ferroelectric while heating the ferroelectric at or above the glass transition point.
Claim 5
Dependent Claim
22 words
A method according to Claim 1, wherein the ferroelectric is heated at or above the glass transition point by a heat-generating electrode.
Claim 6
Dependent Claim
42 words
A method according to Claim 1, wherein the ferroelectric is disposed between a pair of electrodes, and the ferroelectric is heated at or above the glass transition point by irradiation with a semiconductor laser beam through one of the pair of electrodes.
Claim 7
Dependent Claim
45 words
An optical modulation method, comprising: writing in a ferroelectric having a glass transition point at or above the glass transition point, holding the resultant written state below the glass transition point, and optically discriminating the written state as a difference in birefringence of the ferroelectric.
Claim 8
Dependent Claim
45 words
An optical modulation method, comprising: writing in a ferroelectric having a glass transition point at or above the glass transition point, holding the resultant written state below the glass transition point, and optically discriminating the written state as a difference in birefringence of the ferroelectric.
Claim 9
Dependent Claim
18 words
A method according to Claim 6, wherein the written state is discriminated by means of a beam splitter.
Claim 10
Dependent Claim
21 words
An optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes.
Claim 11
Dependent Claim
21 words
An optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes.
Claim 12
Dependent Claim
64 words
An optical modulation apparatus, comprising: an optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes; and means for writing in the ferroelectric at or above the glass transition point to provide a written state given by a difference in birefringence of the ferroelectric and holding the written state below the glass transition point.
Claim 13
Dependent Claim
64 words
An optical modulation apparatus, comprising: an optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes; and means for writing in the ferroelectric at or above the glass transition point to provide a written state given by a difference in birefringence of the ferroelectric and holding the written state below the glass transition point.
Claim 14
Dependent Claim
85 words
An optical modulation apparatus, comprising: an optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes; means for writing in the ferroelectric at or above the glass transition point to provide a written state given by a difference in birefringence of the ferroelectric and holding the written state below the glass transition point; and means for optically discriminating the written state with a difference in birefringence of the ferroelectric held below the glass transition point.
Claim 15
Dependent Claim
85 words
An optical modulation apparatus, comprising: an optical modulation device comprising a pair of electrodes and a ferroelectric having a glass transition point disposed between the electrodes; means for writing in the ferroelectric at or above the glass transition point to provide a written state given by a difference in birefringence of the ferroelectric and holding the written state below the glass transition point; and means for optically discriminating the written state with a difference in birefringence of the ferroelectric held below the glass transition point.
Claim 16
Dependent Claim
19 words
An apparatus according to Claim 10, wherein said ferroelectric is a polymer liquid crystal having a chiral smectic phase.
Claim 17
Dependent Claim
87 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound having a birefringence, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; optical modulation means for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the layer; and means for illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 18
Dependent Claim
87 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound having a birefringence, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; optical modulation means for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the layer; and means for illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 19
Dependent Claim
34 words
An apparatus according to Claim 12, wherein said optical modulation compound is capable of changing its birefringence in response to an electric field applied thereto and said optical modulation means comprises voltage application means.
Claim 20
Dependent Claim
16 words
An apparatus according to Claim 12, wherein said optical modulation compound comprises a nematic liquid crystal.
Claim 21
Dependent Claim
17 words
An apparatus according to Claim 12, wherein said optical modulation compound comprises a chiral smectic liquid crystal.
Claim 22
Dependent Claim
46 words
An apparatus according to Claim 15, wherein said chiral smectic liquid crystal comprises a liquid crystal showing chiral smectic C phase, chiral smectic F phase, chiral smectic I phase, chiral smectic H phase, chiral smectic J phase, chiral smectic G phase or chiral smectic K phase.
Claim 23
Dependent Claim
22 words
An apparatus according to Claim 12, wherein said optical modulation layer causes a change in optical thickness of 0.2 µm or less.
Claim 24
Dependent Claim
96 words
An optical modulation method, comprising: providing an optical modulation device including an optical modulation layer comprising an optical modulation compound having a birefringence and capable of changing the birefringence in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; changing the optical thickness of the optical modulation layer to change the multiple reflection state of the layer; and illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 25
Dependent Claim
96 words
An optical modulation method, comprising: providing an optical modulation device including an optical modulation layer comprising an optical modulation compound having a birefringence and capable of changing the birefringence in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; changing the optical thickness of the optical modulation layer to change the multiple reflection state of the layer; and illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 26
Dependent Claim
45 words
A method according to Claim 18, wherein said optical modulation compound is capable of changing its birefringence in response to an electric field applied thereto and the optical thickness of the optical modulation layer is changed by applying a voltage across the optical modulation layer.
Claim 27
Dependent Claim
132 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound having a glass transition point and a refractive index anisotropy, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; recording means for writing in the optical modulation layer at or above the glass transition point of the optical modulation compound and holding the resultant written state below the glass transition point, said recording means including optical modulation means for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the optical modulation layer; and means for illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 28
Dependent Claim
132 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound having a glass transition point and a refractive index anisotropy, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; recording means for writing in the optical modulation layer at or above the glass transition point of the optical modulation compound and holding the resultant written state below the glass transition point, said recording means including optical modulation means for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the optical modulation layer; and means for illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 29
Dependent Claim
36 words
An apparatus according to Claim 20, wherein said optical modulation compound is capable of changing its refractive index anisotropy in response to an electric field applied thereto, and said optical modulation means comprises voltage application means.
Claim 30
Dependent Claim
16 words
An apparatus according to Claim 20, wherein said optical modulation compound comprises a polymer liquid crystal.
Claim 31
Dependent Claim
17 words
An apparatus according to Claim 20, wherein said optical modulation compound comprises a ferroelectric polymer liquid crystal.
Claim 32
Dependent Claim
22 words
An apparatus according to Claim 20, wherein said optical modulation layer causes a change in optical thickness of 0.2 µm or less.
Claim 33
Dependent Claim
131 words
An optical modulation method, comprising: providing an optical modulation device including an optical modulation layer comprising an optical modulation compound having a glass transition point and a refractive index anisotropy, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; a recording step for writing in the optical modulation layer at or above the glass transition point of the optical modulation compound and holding the resultant written state below the glass transition point, said recording step including a step for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the optical modulation layer; and illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 34
Dependent Claim
131 words
An optical modulation method, comprising: providing an optical modulation device including an optical modulation layer comprising an optical modulation compound having a glass transition point and a refractive index anisotropy, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; a recording step for writing in the optical modulation layer at or above the glass transition point of the optical modulation compound and holding the resultant written state below the glass transition point, said recording step including a step for changing the optical thickness of the optical modulation layer to change the multiple reflection state of the optical modulation layer; and illuminating the optical modulation layer with readout light to optically discriminate the multiple reflection state as a difference in quantity of reflected light.
Claim 35
Dependent Claim
160 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a plane of polarization different from that of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 36
Dependent Claim
160 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a plane of polarization different from that of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 37
Dependent Claim
16 words
An apparatus according to Claim 26, wherein said optical modulation compound comprises a polymer liquid crystal.
Claim 38
Dependent Claim
17 words
An apparatus according to Claim 26, wherein said optical modulation compound comprises a ferroelectric polymer liquid crystal.
Claim 39
Dependent Claim
158 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a wavelength different from that of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 40
Dependent Claim
158 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a wavelength different from that of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 41
Dependent Claim
16 words
An apparatus according to Claim 29, wherein said optical modulation compound comprises a polymer liquid crystal.
Claim 42
Dependent Claim
17 words
An apparatus according to Claim 29, wherein said optical modulation compound comprises a ferroelectric polymer liquid crystal.
Claim 43
Dependent Claim
163 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a wavelength and a plane of polarization different from those of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 44
Dependent Claim
163 words
An optical modulation apparatus, comprising: an optical modulation device including an optical modulation layer comprising an optical modulation compound which has a glass transition point and a refractive index anisotropy and is capable of changing its refractive index anisotropy in response to an electric field applied thereto, the optical modulation layer being set to an optical thickness capable of providing a multiple reflection state; means for irradiating the optical modulation layer with writing light and applying an electric field of one polarity across the optical modulation layer to change the multiple reflection state of the optical modulation layer, thus writing in the optical modulation layer; and means for irradiating the optical modulation layer with erasure light having a wavelength and a plane of polarization different from those of the writing light and applying an electric field of the opposite polarity across the optical modulation layer to again change the multiple reflection state of the optical modulation layer, thus erasing the optical modulation layer.
Claim 45
Dependent Claim
16 words
An apparatus according to Claim 32, wherein said optical modulation compound comprises a polymer liquid crystal.
Claim 46
Dependent Claim
17 words
An apparatus according to Claim 32, wherein said optical modulation compound comprises a ferroelectric polymer liquid crystal.
References Cited (Backward Citations)
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