Light valve, light valve display, and method

A light valve comprising a pair of transparent elements each having a surface portion which has a phase diffraction grating having the same periodicity as, in close juxtaposition to, and having grating lines parallel to those of the like portion of the other, and means for moving one of said surface portions relative to the other in a direction perpendicular to the grating lines, to thereby vary the zero under diffraction transmission.

A light valve comprising two transparent sheets in close juxtaposition to one another each having on the face facing the other a relief grating identical to that on the other and oriented parallel to each other with parallel grating lines and having a depth corresponding to a fraction of the wavelength of the incident light at the frequency of interest, said fraction being one quarter or one half, and means for moving said sheets one with respect to the other in a direction perpendicular to the grating lines over a fraction of the period of said grating, said last-named fraction being one half when the first is a quarter and one quarter when the first is one half.

A light valve comprising a pair of elongated transparent strips, and a support, each said strip having a surface portion which has a phase diffraction grating having the same periodicity as that of, in close juxtaposition to, and facing the like portion of the other strip, and means for moving one of said surface portions relative to the other, said strips being of piezoelectric material, said moving means comprising means to anchor said strips to said support at opposite ends of the strips and transparent electrodes on each strip to receive voltages whereby the strips respond piezoelectrically by strain in opposite directions perpendicular to the grating lines.

A light valve comprising two superimposed identical transparent sheets, said sheets each having one plane side and the other side with a surface described as generated by a straight line moving parallel to itself and to said one plane side and whose distance to said one side varies periodically with the same period D on both said sheets, thereby forming diffraction gratings on the said other side of said sheets, said sheets having said other sides facing each other in close proximity with the grating lines of each parallel to those of the other, and said sheets being movable one with respect to the other in a direction perpendicular to said grating lines.

A light valve comprising a pair of transparent elements each having a surface portion which has a diffraction grating having the same periodicity as, in close juxtaposition to, having the grating lines parallel to those of, and facing the like portion of the other, and voltage responsive means for moving one of said elements relative to the other in a direction at right angles to the grating lines to provide zero order diffraction transmission responsive to an applied voltage.

A device for displaying images comprising light valves, each of said valves comprising a pair of transparent elements, one of each pair having a surface portion which has a phase diffraction grating of depth d and periodicity D with parallel grating lines and the grating lines of each one of a pair having the same periodicity D as, and being parallel to the lines of the other of the pair, each said surface portion in close juxtaposition to and facing the like surface portion of the other of the pair.

A device for displaying images in response to electrical signals comprising a parallel set of vertical strips and a parallel set of horizontal strips, the intersections of said vertical and horizontal strips defining light valve elements, each element consisting of a diffraction grating on the horizontal strip and a facing diffraction grating on said vertical strip, said gratings having the same periodicity, parallel grating lines, and facing each other in close juxtaposition.

A method of controlling the zero order transmission of light comprising placing in closely spaced face-to-face relationship a pair of phase diffraction gratings on a pair of transparent elements, said gratings of each pair having the same periodicity and parallel grating lines, and moving one of the elements relative to the other in a direction perpendicular to the grating lines.

A device for displaying images in response to electrical signals comprising a rigid transparent support having surface portions each of which has a phase diffraction grating, a plurality of transparent parallel lines, each of said transparent lines having surface portions each of which has a phase diffraction grating, the said diffraction gratings of said support and of said transparent lines having the same depth d and the same periodicity D and being in close juxtaposition, the gratings of said transparent lines facing and having grating lines parallel to those of said support.

The method of operating a light valve comprising a pair of transparent elements each having a surface portion which has a phase diffraction grating of depth d and periodicity D, one of said gratings having the same periodicity D as, grating lines parallel to those of, and in close juxtaposition to, and facing the like grating of the other, comprising the steps of:

• moving one of said elements and its said surface portions relative to the other in a direction perpendicular to the grating lines to vary the zero order diffraction transmission, said motion being subject to a substantially sinusoidally oscillating motion in response to a restoring force about a point of zero restoring force,
• releasing the one element at a first time from whatever initial position it may have, and
• then subjecting the element to a locking force substantial at a quarter period of said motion after said first time.