US5658490A
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Liquid crystal achromatic compound retarder
Assignee: COLORADO UNIVERSITY OF BOARD OF REGENTS OF
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Filing: 1995-04-07
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Granted: 1997-08-19
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Expires: 2015-04-07
Abstract
Abstract This invention provides achromatic liquid crystal compound retarders, achromatic polarization switches, and achromatic shutters using the liquid crystal compound retarders. It further provides achromatic variable retardance smectic liquid crystal retarders. The compound retarder of this invention comprises a central liquid crystal retarder unit and two external passive retarders positioned in series with and on either side of the liquid crystal retarder unit. The liquid crystal retarder unit comprises either (1) a rotatable smectic liquid crystal half-wave retarder or (2) first and second liquid crystal variable retarders having retardance switchable between zero and half-wave. The external passive retarders are equal in retardance and orientation to each other. Design equations determine the retardance of the external elements and their orientation relative to the central retarder to obtain a particular achromatic retardance for the compound structure.
Inventors
- 👤 Gary D. Sharp
- 👤 Kristina M. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:13
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1347; G02F1/13471; G02F1/1335; G02F1/13363; G02F1/133638; G02F1/137; G02F1/139; G02F1/1393; G02F1/141; G02F1/1418; G02F2203/00; G02F2203/02; G02F2413/00; G02F2413/02
Claims Analysis
Total Claims: 87
Claim 1
Independent Claim
108 words
A liquid crystal achromatic compound retarder, comprising: a first passive retarder having retardance Γ 1 0 at a design wavelength, and orientation α 1 ; and a second passive retarder having retardance Γ 1 0 at said design wavelength, and orientation α 1 ; and a liquid crystal retarder unit, positioned between said first and second retarders, said retarder unit having composite retardance π at said design wavelength and having composite orientation electronically switchable between α 2 , in a first state, and α 2 ', in a second state; wherein α 1 and α 2 are such that said compound retarder is achromatic in said first state.
Claim 2
Dependent Claim
108 words
A liquid crystal achromatic compound retarder, comprising: a first passive retarder having retardance Γ 1 0 at a design wavelength, and orientation α 1 ; and a second passive retarder having retardance Γ 1 0 at said design wavelength, and orientation α 1 ; and a liquid crystal retarder unit, positioned between said first and second retarders, said retarder unit having composite retardance π at said design wavelength and having composite orientation electronically switchable between α 2 , in a first state, and α 2 ', in a second state; wherein α 1 and α 2 are such that said compound retarder is achromatic in said first state.
Claim 3
Dependent Claim
15 words
The compound retarder of claim 1 wherein cos(2(α 2 -α 1 ))=-π/2Γ 1 0 .
Claim 4
Dependent Claim
18 words
The compound retarder of claim 1 wherein said compound retarder is achromatic in orientation in said second state.
Claim 5
Dependent Claim
11 words
The compound retarder of claim 1 wherein Γ 1 0 =π.
Claim 6
Dependent Claim
12 words
The compound retarder of claim 4 wherein α 2 -α 1 =π/3.
Claim 7
Dependent Claim
12 words
The compound retarder of claim 5 wherein α 2 '-α 2 =π/4.
Claim 8
Dependent Claim
41 words
The compound retarder of claim 1 wherein said liquid crystal retarder unit comprises a planar-aligned smectic liquid crystal retarder having retardance π at said design wavelength and having an optic axis electronically switchable between orientations α 2 and α 2 '.
Claim 9
Dependent Claim
29 words
The compound retarder of claim 7 wherein said smectic liquid crystal retarder is selected from the group consisting of SmC*, SmA*, DHF, antiferroelectric, and achiral ferroelectric liquid crystal retarders.
Claim 10
Dependent Claim
18 words
The compound retarder of claim 7 wherein said smectic liquid crystal retarder is a SmC* liquid crystal retarder.
Claim 11
Dependent Claim
12 words
The compound retarder of claim 9 wherein α 2 '-α 2 =π/4.
Claim 12
Dependent Claim
24 words
The compound retarder of claim 7 wherein said optic axis of said smectic liquid crystal retarder is electronically switchable between more than two orientations.
Claim 13
Dependent Claim
65 words
The compound retarder of claim 1 wherein said liquid crystal retarder unit comprises a first and a second liquid crystal variable retarder, said first variable retarder having an optic axis orientation α 2 and having a retardance electronically switchable between π and 0, said second variable retarder having an optic axis orientation α 2 ' and having a retardance electronically switchable between 0 and π.
Claim 14
Dependent Claim
33 words
The compound retarder of claim 12 wherein said liquid crystal variable retarders are selected from the group consisting of homogeneously aligned nematic liquid crystal cells, π-cells and homeotropically aligned smectic liquid crystal cells.
Claim 15
Dependent Claim
14 words
The compound retarder of claim 12 wherein said liquid crystal variable retarders are π-cells.
Claim 16
Dependent Claim
33 words
An achromatic polarization switch comprising the compound retarder of claim 1 and further comprising a first linear polarizer, having orientation θ 1 , and positioned on a first side of said compound retarder.
Claim 17
Dependent Claim
15 words
The polarization switch of claim 15 wherein cos(2(α 2 -α 1 ))=-π/2Γ 1 0 .
Claim 18
Dependent Claim
25 words
The polarization switch of claim 15 wherein said compound retarder is achromatic in orientation in a second switching state of said liquid crystal retarder unit.
Claim 19
Dependent Claim
22 words
The polarization switch of claim 17 wherein the composite orientation of said compound retarder is θ 1 in said second switching state.
Claim 20
Dependent Claim
11 words
The polarization switch of claim 15 wherein Γ 1 0 =π.
Claim 21
Dependent Claim
12 words
The polarization switch of claim 19 wherein α 2 -α 1 =π/3.
Claim 22
Dependent Claim
12 words
The polarization switch of claim 20 wherein α 2 '-α 2 =π/4.
Claim 23
Dependent Claim
12 words
The polarization switch of claim 21 wherein α 1 =θ 1 +π/12.
Claim 24
Dependent Claim
41 words
The polarization switch of claim 15 wherein said liquid crystal retarder unit is a planar-aligned smectic liquid crystal retarder having retardance π at said design wavelength and having an optic axis electronically switchable between orientations α 2 and α 2 '.
Claim 25
Dependent Claim
65 words
The polarization switch of claim 15 wherein said liquid crystal retarder unit is a first and a second liquid crystal variable retarder, said first variable retarder having an optic axis orientation α 2 and having a retardance electronically switchable between π and 0, said second variable retarder having an optic axis orientation α 2 ' and having a retardance electronically switchable between 0 and π.
Claim 26
Dependent Claim
32 words
An achromatic shutter comprising the polarization switch of claim 15 and further comprising a second linear polarizer, having orientation θ 2 , and positioned on a second side of said compound retarder.
Claim 27
Dependent Claim
15 words
The achromatic shutter of claim 25 wherein cos(2(α 2 -α 1 ))=-π/2Γ 1 0 .
Claim 28
Dependent Claim
42 words
The achromatic shutter of claim 25 wherein said compound retarder is achromatic in orientation in a second switching state of said liquid crystal retarder unit and wherein the composite orientation of said compound retarder is θ 1 in said second switching state.
Claim 29
Dependent Claim
11 words
The achromatic shutter of claim 25 wherein Γ 1 0 =π.
Claim 30
Dependent Claim
12 words
The achromatic shutter of claim 28 wherein α 2 -α 1 =π/3.
Claim 31
Dependent Claim
12 words
The achromatic shutter of claim 29 wherein α 2 '-α 2 =π/4.
Claim 32
Dependent Claim
12 words
The achromatic shutter of claim 30 wherein α 1 =θ 1 +π/12.
Claim 33
Dependent Claim
12 words
The achromatic shutter of claim 31 wherein θ 2 =θ 1 +π/2.
Claim 34
Dependent Claim
41 words
The achromatic shutter of claim 25 wherein said liquid crystal retarder unit is a planar-aligned smectic liquid crystal retarder having retardance π at said design wavelength and having an optic axis electronically switchable between orientations α 2 and α 2 '.
Claim 35
Dependent Claim
24 words
The achromatic shutter of claim 33 wherein said optic axis of said smectic liquid crystal retarder is electronically switchable between more than two orientations.
Claim 36
Dependent Claim
65 words
The achromatic shutter of claim 25 wherein said liquid crystal retarder unit is a first and a second liquid crystal variable retarder, said first variable retarder having an optic axis orientation α 2 and having a retardance electronically switchable between π and 0, said second variable retarder having an optic axis orientation α 2 ' and having a retardance electronically switchable between 0 and π.
Claim 37
Dependent Claim
14 words
A multiple-pixel array comprising a plurality of achromatic shutters as recited in claim 25.
Claim 38
Dependent Claim
76 words
A polarization interference filter comprising the compound retarder of claim 1 and further comprising: a first linear polarizer, having orientation θ 1 , and positioned on a first side of said compound retarder; a second linear polarizer, having orientation θ 2 , and positioned on a second side of said compound retarder; and a third passive retarder, positioned between said first polarizer and said compound retarder, and having retardance Γ 3 and orientation α 3 .
Claim 39
Dependent Claim
13 words
The polarization interference filter of claim 37 wherein α 3 =θ 1 +π/4.
Claim 40
Dependent Claim
32 words
A two-stage filter comprising the polarization interference filter of claim 37 and further comprising: a third linear polarizer; and a second-stage retarder positioned between said third polarizer and said polarization interference filter.
Claim 41
Dependent Claim
14 words
The two-stage filter of claim 39 wherein said second-stage retarder is a passive retarder.
Claim 42
Dependent Claim
18 words
The two-stage filter of claim 39 wherein said second-stage retarder is a second liquid crystal achromatic compound retarder.
Claim 43
Dependent Claim
22 words
The two-stage filter of claim 41 further comprising a second-stage passive retarder positioned between said third polarizer and said polarization interference filter.
Claim 44
Dependent Claim
76 words
A split-element filter comprising the polarization interference filter of claim 38 and further comprising: a fourth passive retarder, positioned between said third passive retarder and said second polarizer, and having orientation θ 1 ; and a fifth passive retarder, positioned between said fourth passive retarder and said second polarizer, and having retardance Γ 3 and orientation θ 1 ±π/4; neither said fourth nor said fifth passive retarder being positioned between said first and second passive retarders.
Claim 45
Dependent Claim
22 words
The split-element filter of claim 43 wherein said fourth passive retarder is positioned between said third passive retarder and said compound retarder.
Claim 46
Dependent Claim
22 words
The split-element filter of claim 44 wherein said fifth passive retarder is positioned between said fourth passive retarder and said compound retarder.
Claim 47
Dependent Claim
21 words
The split-element filter of claim 44 wherein said fifth passive retarder is positioned between said compound retarder and said second polarizer.
Claim 48
Dependent Claim
21 words
The split-element filter of claim 43 wherein said fourth passive retarder is positioned between said compound retarder and said second polarizer.
Claim 49
Dependent Claim
22 words
The split-element filter of claim 43 further comprising a second liquid crystal achromatic compound retarder positioned between said first and second polarizers.
Claim 50
Dependent Claim
25 words
The split-element filter of claim 45 further comprising a second liquid crystal achromatic compound retarder positioned between said first polarizer and said third passive retarder.
Claim 51
Dependent Claim
26 words
The split-element filter of claim 46 further comprising a second liquid crystal achromatic compound retarder positioned between said third passive retarder and said fourth passive retarder.
Claim 52
Dependent Claim
20 words
A color filter comprising the polarization switch of claim 15 wherein said first polarizer is a first pleochroic linear polarizer.
Claim 53
Dependent Claim
22 words
The color filter of claim 51 further comprising a second pleochroic linear polarizer positioned on a second side of said compound retarder.
Claim 54
Dependent Claim
32 words
The color filter of claim 52 further comprising a second liquid crystal achromatic compound retarder positioned on the opposite side of said second pleochroic linear polarizer from said first pleochroic linear polarizer.
Claim 55
Dependent Claim
32 words
The color filter of claim 53 further comprising a third pleochroic linear polarizer positioned on the opposite side of said second liquid crystal achromatic compound retarder from said second pleochroic linear polarizer.
Claim 56
Dependent Claim
34 words
The color filter of claim 54 further comprising a third liquid crystal achromatic compound retarder positioned on the opposite side of said third pleochroic linear polarizer from said second liquid crystal achromatic compound retarder.
Claim 57
Dependent Claim
31 words
The color filter of claim 55 further comprising a neutral linear polarizer positioned on the opposite side of said third liquid crystal achromatic compound retarder from said third pleochroic linear polarizer.
Claim 58
Dependent Claim
25 words
A color filter comprising the polarization switch of claim 15 and further comprising a color polarizer positioned on a second side of said compound retarder.
Claim 59
Dependent Claim
16 words
The color filter of claim 57 wherein said color polarizer is a first cholesteric circular polarizer.
Claim 60
Dependent Claim
15 words
The color filter of claim 58 wherein said compound retarder has a quarter-wave composite retardance.
Claim 61
Dependent Claim
36 words
The color filter of claim 58 wherein said compound retarder has a half-wave composite retardance and wherein said color filter further comprises a passive quarter-wave plate positioned between said compound retarder and said cholesteric circular polarizer.
Claim 62
Dependent Claim
15 words
The color filter of claim 60 wherein said quarter-wave plate has orientation θ 1 ±π/4.
Claim 63
Dependent Claim
24 words
The color filter of claim 58 further comprising a second cholesteric circular polarizer positioned between said compound retarder and said first cholesteric circular polarizer.
Claim 64
Dependent Claim
16 words
The color filter of claim 57 wherein said color polarizer is a first pleochroic linear polarizer.
Claim 65
Dependent Claim
15 words
The color filter of claim 63 wherein said compound retarder has a half-wave composite retardance.
Claim 66
Dependent Claim
24 words
The color filter of claim 63 further comprising a second pleochroic linear polarizer positioned between said compound retarder and said first pleochroic linear polarizer.
Claim 67
Dependent Claim
126 words
An achromatic shutter comprising: a first linear polarizer oriented at an angle θ 1 ; a second linear polarizer oriented at an angle θ 2 ; a liquid crystal retarder unit, positioned between said first and second polarizers, said retarder unit having composite retardance π at a design wavelength and having composite orientation electronically switchable between 5π/12 and 8π/12 with respect to θ 1 ; a first retarder, positioned between said first polarizer and said liquid crystal retarder unit, having retardance π at said design wavelength and orientation π/12 with respect to θ 1 ; and a second retarder, positioned between said second polarizer and said liquid crystal retarder unit, having retardance π at said design wavelength and orientation π/12 with respect to θ 1 .
Claim 68
Dependent Claim
126 words
An achromatic shutter comprising: a first linear polarizer oriented at an angle θ 1 ; a second linear polarizer oriented at an angle θ 2 ; a liquid crystal retarder unit, positioned between said first and second polarizers, said retarder unit having composite retardance π at a design wavelength and having composite orientation electronically switchable between 5π/12 and 8π/12 with respect to θ 1 ; a first retarder, positioned between said first polarizer and said liquid crystal retarder unit, having retardance π at said design wavelength and orientation π/12 with respect to θ 1 ; and a second retarder, positioned between said second polarizer and said liquid crystal retarder unit, having retardance π at said design wavelength and orientation π/12 with respect to θ 1 .
Claim 69
Dependent Claim
12 words
The achromatic shutter of claim 66 wherein θ 2 -θ 1 =π/2.
Claim 70
Dependent Claim
44 words
The achromatic shutter of claim 66 wherein said liquid crystal retarder unit comprises a planar-aligned smectic liquid crystal retarder having retardance π at said design wavelength and having an optic axis electronically switchable between orientations 5π/12 and 8π/12 with respect to θ 1 .
Claim 71
Dependent Claim
29 words
The achromatic shutter of claim 68 wherein said smectic liquid crystal retarder is selected from the group consisting of SmC*, SmA*, DHF, antiferroelectric, and achiral ferroelectric liquid crystal retarders.
Claim 72
Dependent Claim
18 words
The achromatic shutter of claim 68 wherein said smectic liquid crystal retarder is a SmC* liquid crystal retarder.
Claim 73
Dependent Claim
72 words
The achromatic shutter of claim 66 wherein said liquid crystal retarder unit comprises a first and a second liquid crystal variable retarder, said first variable retarder having an optic axis orientation 5π/12 with respect to θ 1 and having a retardance electronically switchable between π and 0, said second variable retarder having an optic axis orientation 8π/12 with respect to θ 1 and having a retardance electronically switchable between 0 and π.
Claim 74
Dependent Claim
33 words
The achromatic shutter of claim 71 wherein said liquid crystal variable retarders are selected from the group consisting of homogeneously aligned nematic liquid crystal cells, π-cells and homeotropically aligned smectic liquid crystal cells.
Claim 75
Dependent Claim
14 words
The achromatic shutter of claim 71 wherein said liquid crystal variable retarders are π-cells.
Claim 76
Dependent Claim
14 words
A multiple-pixel array comprising a plurality of achromatic shutters as recited in claim 66.
Claim 77
Dependent Claim
93 words
A reflection-mode liquid crystal achromatic compound retarder, comprising: a first passive retarder having retardance Γ 1 0 at a design wavelength and orientation α 1 ; a reflector; and a liquid crystal retarder unit, positioned between said first retarder and said reflector, said retarder unit having composite retardance π/2 at said design wavelength and having composite orientation electronically switchable between α 2 , in a first state, and α 2 ', in a second state; wherein α 1 and α 2 are such that said compound retarder is achromatic in said first state.
Claim 78
Dependent Claim
93 words
A reflection-mode liquid crystal achromatic compound retarder, comprising: a first passive retarder having retardance Γ 1 0 at a design wavelength and orientation α 1 ; a reflector; and a liquid crystal retarder unit, positioned between said first retarder and said reflector, said retarder unit having composite retardance π/2 at said design wavelength and having composite orientation electronically switchable between α 2 , in a first state, and α 2 ', in a second state; wherein α 1 and α 2 are such that said compound retarder is achromatic in said first state.
Claim 79
Dependent Claim
41 words
The reflection-mode retarder of claim 75 wherein said liquid crystal retarder unit comprises a planar-aligned smectic liquid crystal retarder having retardance π/2 at said design wavelength and having an optic axis electronically switchable between orientations α 2 and α 2 '.
Claim 80
Dependent Claim
65 words
The reflection-mode retarder of claim 75 wherein said liquid crystal retarder unit comprises a first and a second liquid crystal variable retarder, said first variable retarder having an optic axis orientation α 2 and having a retardance electronically switchable between π/2 and 0, said second variable retarder having an optic axis orientation α 2 ' and having a retardance electronically switchable between 0 and π/2.
Claim 81
Dependent Claim
15 words
The reflection-mode retarder of claim 75 wherein cos(2(α 2 -α 1 ))=-π/2Γ 1 0 .
Claim 82
Dependent Claim
22 words
The reflection-mode retarder of claim 75 wherein Γ 1 0 =π, α 2 -α 1 =π/3, and α 2 '-α 2 =π/4.
Claim 83
Dependent Claim
38 words
A reflection-mode shutter comprising the reflection-mode retarder of claim 75 and further comprising a linear polarizer, having orientation θ 1 , and positioned on the opposite side of said first passive retarder from said liquid crystal retarder unit.
Claim 84
Dependent Claim
15 words
The reflection-mode shutter of claim 80 wherein cos(2(α 2 -α 1 ))=-π/2Γ 1 0 .
Claim 85
Dependent Claim
22 words
The reflection-mode shutter of claim 80 wherein Γ 1 0 =π, α 2 -α 1 =π/3, and α 2 '-α 2 =π/4.
Claim 86
Dependent Claim
12 words
The reflection-mode shutter of claim 82 wherein α 1 =θ 1 +π/12.
Claim 87
Dependent Claim
14 words
A multiple-pixel array comprising a plurality of reflection-mode shutters as recited in claim 80.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-18 | 2001-02-17 | 2001-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-18 | 2005-02-17 | 2005-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-18 | 2009-02-17 | 2009-08-19 | $7700.00 | Window Closed / Lapsed |