Improved optical combiner collimating apparatus

Claim 2

An optical combiner for combining a first image incident on said combiner in a first direction with a second image incident on said combiner in a second direction, characterised in that said combiner comprises at least one cholesteric liquid crystal element (30) for transmitting said first image in said first direction and for reflecting said second image in said first direction.

Claim 3

An optical combiner as claimed in claim 1, wherein said at least one cholesteric element (30) comprises a plurality of cholesteric liquid crystal elements each having a maximum reflectivity at a different colour.

Claim 4

An optical combiner as claimed in claim 2, wherein said plurality of cholesteric elements are deposited in layers one on another to form a single element.

Claim 5

A colour shutter for receiving a monochrome image and for transmitting a plurality of coloured images characterised by: a plurality of cholesteric liquid crystal elements (30A, 30B) disposed in series, each cholesteric element having a maximum reflectivity at a different colour; and an optical element disposed after said cholesteric elements for switching light output between said different colours.

Claim 6

A colour shutter for receiving a monochrome image and for transmitting a plurality of coloured images characterised by: a plurality of cholesteric liquid crystal elements (30A, 30B) disposed in series, each cholesteric element having a maximum reflectivity at a different colour; and an optical element disposed after said cholesteric elements for switching light output between said different colours.

Claim 7

A colour shutter as claimed in claim 4, wherein said optical switching element comprises a liquid crystal colour shutter having an output responsive to an input voltage state.

Claim 8

A colour shutter as claimed in claim 4, wherein at least two of said cholesteric elements have a different circular polarity, whereby at least two different colours have a different circular polarity.

Claim 9

An optical collimating apparatus for focussing an image at or closer than an infinite distance from an observer in a line of sight from said observer characterised by: at least one cholesteric liquid crystal element (30) disposed in said line of sight for polarizing said image; a semireflective concave mirror (42) disposed in said line of sight after said at least one element (30) for transmitting said image; and a second cholesteric liquid crystal element (44) disposed in said line of sight after said concave miror for transmitting a first portion of said image to said observer and for reflecting a second portion of said image back to said mirror, said mirror reflecting said second portion back to said second cholesteric element, said second cholesteric element transmitting said second portion to said observer.

Claim 10

An optical collimating apparatus for focussing an image at or closer than an infinite distance from an observer in a line of sight from said observer characterised by: at least one cholesteric liquid crystal element (30) disposed in said line of sight for polarizing said image; a semireflective concave mirror (42) disposed in said line of sight after said at least one element (30) for transmitting said image; and a second cholesteric liquid crystal element (44) disposed in said line of sight after said concave miror for transmitting a first portion of said image to said observer and for reflecting a second portion of said image back to said mirror, said mirror reflecting said second portion back to said second cholesteric element, said second cholesteric element transmitting said second portion to said observer.

Claim 11

An apparatus as claimed in claim 7, wherein said cholesteric elements substantially all have the same circular polarity.

Claim 12

An apparatus as claimed in claim 7, wherein said second cholesteric element comprises a plurality of cholesteric elements each having a maximum reflectivity at a different colour.

Claim 13

An optical collimating system for focussing an image at or closer than an infinite distance from an observer in a line of sight from said observer, characterised by: an image source (32) for generating a first image; a transmitter/combiner, said transmitter/combiner comprising at least one cholesteric liquid crystal element (30) for transmitting a second image in said line of sight and for reflecting said first image in said line of sight; a semireflective concave mirror (42) disposed in said line of sight for transmitting said images; and a second cholesteric liquid crystal element (44) disposed in said line of sight after said concave mirror for transmitting said second image and a first portion of said first image to said observer and for reflecting a second portion of said first image back to said mirror, said mirror receiving said second portion and reflecting said first portion back to said second cholesteric element, said second cholesteric element transmitting said first portion to said observer.

Claim 14

An optical collimating system for focussing an image at or closer than an infinite distance from an observer in a line of sight from said observer, characterised by: an image source (32) for generating a first image; a transmitter/combiner, said transmitter/combiner comprising at least one cholesteric liquid crystal element (30) for transmitting a second image in said line of sight and for reflecting said first image in said line of sight; a semireflective concave mirror (42) disposed in said line of sight for transmitting said images; and a second cholesteric liquid crystal element (44) disposed in said line of sight after said concave mirror for transmitting said second image and a first portion of said first image to said observer and for reflecting a second portion of said first image back to said mirror, said mirror receiving said second portion and reflecting said first portion back to said second cholesteric element, said second cholesteric element transmitting said first portion to said observer.

Claim 15

A collimating system as claimed in claim 10, said at least one cholesteric element comprising a plurality of cholesteric liquid crystal elements each having a maximum reflectivity at a different colour.

Claim 16

A collimating system as claimed in claim 10, wherein said at least one cholesteric element is for polarizing said first image.

Claim 17

A collimating system as claimed in claim 10, wherein said cholesteric elements are disposed on opposing sides of said semireflective mirror.

Claim 18

A collimating system as claimed in claim 10, wherein said second cholesteric element comprises a plurality of cholesteric liquid crystal elements each having a maximum reflectivity at a different colour.

Claim 19

A helmet mounted display system characterised by: a helmet (22) having a visor (24) for viewing the environment; and an optical combiner (30) disposed on said visor for combining a first image incident on said combiner from said environment with a second image incident on said combiner from a helmet mounted optical path; said combiner comprising at least one cholesteric liquid crystal element.

Claim 20

A helmet mounted display system characterised by: a helmet (22) having a visor (24) for viewing the environment; and an optical combiner (30) disposed on said visor for combining a first image incident on said combiner from said environment with a second image incident on said combiner from a helmet mounted optical path; said combiner comprising at least one cholesteric liquid crystal element.

Claim 21

A display system as claimed in claim 15, further comprising at least one liquid crystal colour shutter element mounted in said helmet and disposed in said optical path ahead of said combiner.