GB2575235A

GB2575235A - Electro-optic photoreactive raster or vector beam scanner for highlight projectors

Info

Publication number: GB2575235A
Application number: GB1807462.5A
Authority: GB
Inventors: Jan Doornaert Dries
Original assignee: Barco NV
Current assignee: Barco NV
Priority date: 2018-05-08
Filing date: 2018-05-08
Publication date: 2020-01-08
Also published as: GB201807462D0

Abstract

A laser beam 2 emitted from a first laser light source is incident on a first electro-optic crystal 1 exhibiting the Kerr or Pockel effect, passes through a half-wave plate 18 and is incident on a second electro-optic crystal 11 exhibiting the Kerr or Pockel effect, after emerging from the second electro-optic crystal the beam is directed through at least one optical component 20 towards a projection screen; voltages applied to the crystals are controlled to generate a laser beam spot that is directed to any position on the projection screen. In some embodiments the projection screen may be a 2D projection screen. In some embodiments the laser beam spot may display highlighting for a projected image. The projected image may be projected by a separate projector or be processed along a second optical path. The beam leaving the electro-optic crystal may be incident on a spatial light modulator.

Description

ELECTRO-OPTIC PHOTOREACTIVE RASTER OR VECTOR BEAM SCANNER FOR HIGHLIGHT PROJECTORS

The present invention relates to highlight projectors, to optical subunits for deflecting a laser beam, to methods of constructing and operating such projectors or sub-units and software for implementing such methods.

Background

A multi-stage modulation projector system typically has a single light source that illuminates a screen with an image that is modulated by some optical system within the projector. Some projectors have the capability of highlighting. This can be done by a dedicated spatial light modulator, e.g. with micro-mirrors modulator to provide mechanical beam steering of the beam used for highlighting. Highlight modulators preferably can steer the incident light beam to any location of an image to be projected where a particular part is to be highlighted by increasing its luminosity.

US2016/0139560 discloses a projector system with at least one highlight modulator that employs non-mechanical beam steering, i.e. does not rely on moveable micro-mirror(s). The projector display system comprises a light source; a controller; a first holographic modulator, said first modulator being illuminated by said light source and said first modulator comprising a holographic imaging module; a lens, said lens adapted to transmit from said first holographic modulator; a second modulator, said second modulator being illuminated by light from said lens and capable of modulating light from said lens, and said second modulator comprising a plurality of mirrors. Control signals are sent to said first holographic modulator such that said first holographic modulator may allocate a desired proportion of the light from said light source onto said second modulator; and control signals are sent to said second modulator such that said desired proportion of the light from said light source is modulated to form said desired image for projection.

The display system may include a polarizer, said polarizer being illuminated by said light source and said polarizer inducing a desired polarization to the light from said light source;

a beam expander, said beam expander expanding said light from said polarizer; a first partial beam splitter, said first partial beam splitter capable of splitting the light preferentially along a main light path and a highlight path; a spatial light modulator, said spatial light modulator receiving said light along said highlight path and modulating said light along said highlight path to create a desired highlight light; a second partial beam splitter, said second partial beam splitter capable of combining light from said main light path and said highlight path. The image data can comprise at least one highlight feature.

Although the known non-mechanical beam steering may be advantageous in principle it has certain drawbacks. If an LCD panel is used to form the holographic image, the panel absorbs light which is a waste of energy as well as causing heating. If light from the light source is split, e.g. by its polarization, then light for the main image is lost. In addition to the sub-optimal use of light and hence the low light efficiency the geometry can be complex.

In the article entitled “KTN Crystals Open Up New Possibilities and Applications” by Shogo Yagi, November 2, 2011, NTT Technical review, it is stated that the resolution of the present KTN devices is insufficient for printers, copiers, and displays, whereby the present resolution is sufficient for spectrometers and medical use.

Summary of the invention.

A method of providing highlighting in a projector system, the method comprising a laser beam emitted from a first laser light source is incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passes through a half-wave plate and is incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electrooptic crystal exhibiting the Kerr or Pockel effect are controlled to generate a laser beam spot that is directed to any position on the 2D projection screen.

A system for providing highlighting in a projector system, the system comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, and first and second means for applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to generate a laser beam spot that is directed to any position on the 2D projection screen.

Embodiments of the present invention provide a method of providing highlighting in a proj ector system, the method comprising a laser beam emitted from a first laser light source passing along an optical path comprising incidence on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect being directed through at least one optical component towards a projection screen, voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect are controlled to generate a laser beam spot that is directed to any position on the projection screen to display highlighting for a projected image.

The advantage of this method is the high speed that can be achieved with light steering by electro-optic crystals exhibiting the Kerr or Pockel effect.

The projected image is projected by a separate projector or is processed along a second optical path and displayed. By using a separate projector for the main image or by using a separate optical path, the highlights can be given a higher light intensity.

The beam leaving the electro-optic crystal is preferably incident on a spatial light modulator. This allows unwanted highlights to be dumped, e.g. typically the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the spatial light modulator is driven to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

The voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel are driven to keep the average applied voltage equal to zero volts. This avoids drift effects.

The method allows for compensating for a changing DC voltage level.

The DC drift ng can be measured with an electronic integrator circuit and ADC converters, or computed it directly when computing highlight locations, or monitoring the output spot with an imaging device and adjusting accordingly. Controlling drift increases the accuracy of beam placement in the final projected image.

The method can include blanking of the beam from the first laser source during compensation, or compensation by placing the first laser source on the aperture, or using multiple crystals so one crystal is “reset” while the other(s) is/are being used.

All these techniques improve the operation of the scanner unit.

The method can also include the steps:

load a video frame find highlight location subtract highlight from video frame store coordinate compute masking pattern generate spots for highlighting.

The step of finding highlight locations in the projected image can be via the steps: divide the video frame into many small non-overlapping segments and determine for each segment whether or not a highlight is required, if required the highlight is placed centrally in the segment, and subtract the highlight for each required segment and repeat the above steps.

The step of finding highlight locations in the projected image can be via the steps: divide the video frame into many small non-overlapping segments, determine for a segment if a highlight is required, subtract the highlight on its exact spot for this segment, and move to the next segment and repeat above steps.

The step of finding highlight locations in the projected image can be via the steps: divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment if a highlight has been found, repeat for the same segment if not, move to the next segment and repeat above steps.

In another aspect embodiments of the present invention provide a system for highlighting images produced by one or more projectors, the system comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electrooptic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, and first and second means for applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to generate a laser beam spot that is directed to any position on the 2D projection screen.

The system can include a separate projector for projecting an image, or a second optical path along which the projected image is processed and projected and displayed.

The beam leaving the electro-optic crystal can be incident on a spatial light modulator. Spatial light modulators are standard components.

The spatial light modulator can have a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the spatial light modulator is driven to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

The system may include a unit to generate voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel and the unit is driven to keep the average applied voltage equal to zero volts.

The system may include means for compensating for a changing DC voltage level.

The system may include means for determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly

The system may be adapted for:

Blanking of the beam from the first laser source during compensation, or Compensation by placing the first laser source on the aperture, or

Using multiple crystals so one crystal is “reset” while the other(s) is/are being used.

The system can have:

means to load a video frame means to find a highlight location means to subtract a highlight from video frame means to store coordinate means to compute a masking pattern, and means to generate spots.

The means for finding a highlight location in the projected image can be adapted to:

divide the video frame into many small non-overlapping segments and determine for each segment whether or not a highlight is required, if required the highlight is placed centrally in the segment, and subtract the highlight for each required segment and repeat the above steps.

The means to find a highlight location in the projected image can be adapted to: divide the video frame into many small non-overlapping segments, determine for a segment if a highlight is required, subtract the highlight on its exact spot for this segment, and move to the next segment and repeat above steps.

The means to find a highlight location in the projected image can be adapted to: divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment if a highlight has been found, repeat for the same segment if not, move to the next segment and repeat above steps.

In another aspect embodiments of the present invention provide a computer program product which is adapted to execute any of the methods of the present invention when executed on a processing engine.

A non-transitory signal storage medium can store the computer program product. Embodiments of the present invention provide a controller for a projector providing highlighting, the projector comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, the controller comprising first and second means for controlling the application of voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot that is directed to any position on the 2D projection screen.

Embodiments of the present invention provide a raster or vector beam scanner for highlight projectors comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a halfwave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, and first and second means for applying voltages to the first electrooptic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot to any position on the 2D projection screen.

Brief description of the figures

Figure 1A shows a line scanner with a single electro-optic refractive crystal.

Figures IB to 10 show 2D beam steering units with dual electro-optic refractive crystals in accordance with embodiments of the present invention.

Figure 11 shows a highlighter projector schematically which can include any of the 2D beam steering units of Figures IB to 10 according to embodiments of the present invention. Figure 12 shows a highlighter projector schematically which can include any of the beam steering units of Figures IB to 10 according to embodiments of the present invention, the figure showing in particular the light spots created by the beam steering units.

Figures 13 A to 15B show different embodiments of the present invention including beam steering units of any of the figures IB to 10.

Figure 16 shows the combination of a separate base projectors and highlighter projector according to an embodiment of the present invention.

Figure 17 to 25 show further embodiments of the present invention including beam steering units according to any of Figures IB to 10, or arrangements disclosed in Figures 13A to 15B.

Figure 26 is a schematic representation of coloured base light from a base light projector being combined with coloured light from a highlight projector comprising any of the beam steering units described in any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13a, or b to 15 a, or b at an angle combined via etendue according to embodiments of the present invention. The combined beam is then sent to the projection lens system.

Figure 27 is a schematic representation of a driving circuit, e.g. with DC offset for use with embodiments of the present invention e.g. in the range 0 to plus or minus 250 Volt such as 100 Volt and a superimposed AC voltage such as an AC voltage with a maximum of +/250V. The wave forms comprise small steps being transient for 1 to 5 micro sec or 10 microsec, or up to 25 microsec or up to 400 microsec.

Figures 28A and 28B show how drive pulses can be split into two for any of the embodiments of the present invention, so that each plus has one up and one down flank, in order to have an AC signal that guarantees a zero volt average. Sending an AC pulse instead of a DC pulse means that instead of one spot two spots 195, 197 are generated. These can be arranged such that one spot is where it should be and one on the other side. Assuming one dumps the second side then 50% of the light is lost. The undesired spots contain half of the total energy. It is thus important to recuperate this light. This can be done by mirrors or by a special lens as described below.

Figures 29A and 29B show embodiments of the present invention which make use of a mirror. In Figure 29A a flat mirror 190 is shown that reflects the light from the laser 192 from the moment the light exits the electro-optic crystal such as a KTN cell 194. This configuration places the up and down laser spot on top of each other. Figure 29B shows a curved mirror 196 that reflects the light from the laser 192 at a distance from the electrooptic crystal such as a KTN cell 194. This configuration also places the up and down laser spots on top of each other.

Figure 29C shows a lens 198 that deflects the light exiting the the electro-optic crystal such as a KTN cell 194 in the bottom part and passes the light to the top part.

The deflection is such that the bottom spot arrives at the same location as the top spot for use with any of the embodiments of the present invention.

Figure 29D shows a 3D layout of a lens as shown in Figure 29C that compensates bottom to top and right to left for use with any of the embodiments of the present invention. Figure 30 shows the flow diagram of a method to be used with any of the embodiments of the present invention.

Figures 31A to 32C show different embodiments of the present invention for the elastic support of electro-optic refractive crystal for use with any of the embodiments of the present invention.

Figure 33 shows a highlight projector according to an embodiment of the present invention. Figures 34A to 34D show arrangements of an electro-optic crystal such as a KTN crystal covered with electrodes according to embodiments of the present invention.

Definitions

The term laser scanning is used for the controlled deflection of laser beams, i.e. the controlled steering of laser beams. In raster scanning the beam is made to follow a sequence of lines, one after another. In vector scanning the beam is move to a particular position, i.e. the beam traverses a path defined by a vector.

An electro-optic crystal as used in embodiments of the present invention is a photorefractive crystal exhibiting the Pockel or Kerr effect. Such a crystal provides a photorefractive effect to move, e.g. scan a laser beam. Particularly preferred are electrooptic crystals exhibiting the Kerr effect driven to a trapped space charge effect. An electrooptic crystal can be used to deflect a laser beam whereby the deflection can be made by refraction at the interfaces of an optical prism. A KTN crystal can be used but this results in lower deflection angles. Preferably the deflecting is generated in an electro-optic crystal with Kerr or Pockel effect driven to a trapped space charge effect. The deflection is caused by an index gradient (GRIN) that is applied perpendicular to the direction of propagation of the laser beam. Suitable electro-optic crystals can be made from potassium tantalate niobate (KTN, a preferred crystal). Electro-optic, photorefractive crystal examples:

• Beta Batrium Borate (BBO) • Bismuth Borate (BIBO) useful for highlighter applications • Lithium Triborate (LBO) • Potassium Dideuterium Phosplate (KDP, KD*P, DKDP) • Potassium Titanyl Phosphate (KTP) • Potassium Titanyl Arsenate (KTA) • AgGaS2, AgGaSe2, GaSe, ZnGeP2 (infrared crystals) • Lithium Iodate (LiIO3) • Lithium Niobate (LiNbO3) • Cadmium Selenide (CdSe)

The article “Three order increase in scanning speed of space charge-controlled KTN deflector by eliminating electric field induced phase transition in nanodisordered KTN” by Wenbin Zhu, Ju-Hung Chao, Chang-Jiang Chen, Shizhuo Yin & Robert C. Hoffman, Sei. Rep. 6, 33143; doi: 10.1038/srep33143 (2016) is incorporated herein in its entirety by reference. A space-charge-controlled KTN beam steering unit achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal is preferred in any of the embodiments of the present invention. The beam steering unit can be operated at a temperature slightly above or below the Curie temperature. It is preferred if an electric field is generated in the crystal that does not cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase, which causes the deflection of a laser beam to operate in the linear electro-optic regime. It is preferred if the scanning speed of the beam steering unit is not limited by the electron mobility within the KTN crystal. It is preferred if this speed limitation caused by the EFIPT is and the scanning speed can be in the nanosecond regime. Electro-optic crystals made of potassium tantalate niobate (KTN) have the advantage of an exceptionally large quadratic electro-optical coefficient. KTN crystals have the advantage of

High dielectric constant

High refractive index : 2. I4~2.33

Large Electro-Otic effect e.g. by Kerr or Pockel effect, which is proportional to the square of electric field.

High nonlinear optical coefficient: 20~60 times larger than that of quartz

High electro-mechanical coupling coefficient:

High light transmittance: substantially 100% in the range of 488~3500nm

Several crystal structures such as cubic, tetragonal, orthorhombic, rhombohedral, are available and with unique properties. When used in a highlight projector the lower resolution of electro-optic crystals is less important.

Detailed description of the illustrative embodiments

An aspect of the present invention is to create brightly illuminated spots (“highlights”) on a display or projection screen by moving a light beam such as a white and/or colored light beam such as a laser beam or a combination of laser beams such as laser beams of primary colours such as RGB lasers to any position of a projected image. These spots can be used for creating or modify video content such as providing highlighting, vector-scanning, or laser shows. Embodiments of the present invention include raster or vector-scanning but vector scanning is preferred.

It is preferred that if the spots are to be applicable for movies, then the position of the spot or spots e.g. for highlights are computed at framerate and are generated in a l-100ps time scale. The transition from a spot being in one position on an image, e.g. to make a first highlight to another position to make a second highlight should preferably happen in an as short time as possible. The light source such as the laser can be shut down in the process, i.e. in between spots to be illuminated. Further, the order in which highlights at different positions are addressed is preferably controlled to reduce transition times and to reduce “light trails” as a laser spot sweeps across an area of the display.

Embodiments of the present invention make use of a raster or vector scanner having a lack of mechanical moving parts. Deflection of a light beam such as a laser is achieved with control of an electro-optic crystal achieved by a photorefractive effect such as in a KTN crystal. Embodiments of the present invention include an electro-optic and electronic system which is controlled by a controller which is configured to apply control voltages and currents. The system can have large deflection angles/resolution and can reach resonant speeds high enough for raster scanning and/or transition times low enough for vector scanning.

With reference to Figure 1A, a signal voltage 3 applied across an electro-optic crystal 1 such as a KTN crystal will generate an electric field and GRIN (graded index) behavior via induced birefringence. This means that a light beam 2 such as a laser passing through the crystal 1 will be deflected in the direction of the electric field in accordance with a photorefractive effect. GRIN (graded index) behavior is in one direction, i.e. the direction of the applied electric field.

By switching the voltage (positive or negative) on the crystal 1, the deflection angle 4 can be controlled allowing for beam scanning or vectoring. The beam deflection generated by the electro-optic crystal 1 such as the KTN crystal can also, under certain circumstances, induce a lensing effect. This lensing effect, if it is present, can be compensated by use of a cylindrical lens 5 added after the electro-optic crystal 1. In Figure 1A and in some or all of the embodiments of the present invention the deflecting of a laser beam is generated in an electro-optic crystal with Kerr or Pockel effect driven to a trapped space charge. The deflection is caused by an index gradient (and is hence a photorefractive effect), that is applied perpendicular to the direction of propagation of the laser beam. A crystal for operation in space charge mode is constructed with specific electrodes to ensure that electrons are injected in the crystal. These electrons create a distribution of the refractive index in the crystal. Due to this distribution a large deflection angle can be achieved. This procedure works very well with low power laser of modest wavelengths (from green to infrared).

The electro-optic crystal with a graded refractive index distribution provides an electrooptical modulation of a light beam from a laser and a beam collimator. A KTN crystal in operation has flat conductive electrodes connected with an external modulation voltage source. For a raster scan the voltage source is a sine wave. For vector scanning a voltage is applied to move the laser beam spot to the correct position on the projected image. The incident light beam is modulated by the KTN crystal, the outgoing beam trajectory is sent towards a projection lens.

Electro-optic crystals such as the KTN crystals have generally had a pyramidal shape. An electro-optic crystal such as the KTN crystal 1 and/or 11 (see Figure lb) as used in any of the embodiments of the present invention can be rectangular shape on which an electrode is patterned to convert the crystal into a prismatic shape. As shown in any of the figures 34A to 34D the laser beam 2 is steered by means of the electro-optic crystal such as the KTN crystal. Figure 34A shows a generally rectangular electro-optic crystal such as the KTN crystal 550 covered with an electrode 552 on top and sides and shaped to convert the crystal into a pyramidal effective shape. There can be multiple prisms on the same crystal - see Figure 34B which shows multiple pyramidal sections 556 of crystal. In addition to the rectangular crystal 550 being made effectively pyramidal by means of electrodes 552, the electro-optic crystal such as the KTN crystal 1 and/or 11 may have an additional triangular or prismatic part of crystal 556 at least on one face as shown in Figures 34C and 34D. As shown in Figures 34C and 34D this extra piece 556 may be covered with electrode material or can be naked crystal depending on the design.

One advantage of the use of the electrodes to change the effective shape of the crystal is that the deflection angle is not limited by total internal deflection due to the rectangular shape. Also there are less reflection losses and a much better and easier design for antireflection coatings.

A potential disadvantage is that it uses double the amount of crystal compared to a crystal which itself is prismatic in shape.

Fig. IB shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Also it may be more likely to suffer more from stress and there may be more edge effects at the interface between electrode and no electrode.

The photonic modulation system is polarisation dependent. It is thus required to have two electro-optic crystals 1, 11 in series in order to scan in a two-dimensional manner, i.e. for XY-scanning two electro-optic crystals 1, 11 such as KTN crystals are placed in series. With reference to Figure lb, a signal voltage 3 applied across an electro-optic crystal 1 such as a KTN crystal and a second electro-optic crystal 11 will in each case generate an electric field and GRIN (graded index) behavior via induced birefringence. Between the two electro-optic crystals such as the KTN crystals 1 and Ila half wave plate 18 is placed to alter the polarization of the laser beam to align it with the GRIN of the second electrooptic crystal such as the KTN crystal 11. This means that a light beam 2 such as a laser passing through the crystal 1 will be deflected in the direction of a first electric field in one direction and the beam will be deflected in a second direction orthogonal to the first direction in the direction of the electric field in the second electro-optic crystal such as the KTN crystal 11. This arrangement provides a working embodiment for an optical beam steering unit in a projector but can be improved as explained below.

Suitable electro-optic crystals can be made from potassium tantalate niobate (KTN, a preferred crystal). Such non-linear crystals are used for frequency conversion of lasers, in resonators, optical parametric oscillators (OPO) and optical heads. Non-linear optical crystals are used in wide range of optical frequency conversion applications including laser harmonic generations (SHG, THG, 4HG), sum or difference frequency generation (SFG, DFG) and optical parametric generation, amplification or oscillation (OPG, OP A, OPO) e g. 1064nm (IR) doubles(SHG) to 532nm(green) and triples(THG) to 354 nm (UV).

Further electro-optic, photorefractive crystal examples:

Figure 2 shows along the optical axis the optical components of light source such as a laser beam 2, a beam collimator 15 emitting a polarized laser beam (e.g. linearly polarized) which can be aligned parallel or perpendicular with the GRIN of a first electro-optic crystal such as a KTN crystal 1, an optional first compensation lens 16, for removing undesired lens effects as well as focusing or defocusing, a half wave plate 18 to turn the polarization of the laser beam through 90° (e.g. linearly polarized light) to align this polarization with the GRIN grading aligned either perpendicular or parallel of a second electro-optic crystal such as a KTN crystal 11, an optional second compensation lens 19 , for removing undesired lens effects as well as focusing or defocusing, and an application dependent beam shaping optics 20, e.g. for any of or combination of spot expansion, collimation, colour conversion, angle enlarging or compression, focusing etc. Fig. 2 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 3 shows along the optical axis the optical components of a light source such as a laser beam 2, a beam collimator 15 emitting a polarized laser beam (e.g. linearly polarized) aligned with the GRIN of a first electro-optic crystal such as a KTN crystal 1, an optional first compensation lens 16 , for removing undesired lens effects as well as focusing or defocusing, an optional first cylindrical compensation lens 17 to compensate for any lensing introduced by the first electro-optic crystal such as the KTN crystal 1, a half wave plate 18 to turn the polarization of the laser beam through 90° (e.g. linearly polarized light) and to align this polarization with the GRIN of a second electro-optic crystal such as a KTN crystal 11, an optional second compensation lens 19, for removing undesired lens effects as well as focusing or defocusing and an optional first cylindrical compensation lens 21 to compensate for any lensing introduced by the second electro-optic crystal such as the KTN crystal 11. In the optics of Figure 3 the laser beam is bent by the first electro optic crystal such as the KTN crystal 1 and realigned with the optical axis by the cylindrical lens 17. This allows for an easier and cleaner transmission through the second electro-optic crystal such as the KTN crystal 11. To restore the deflection caused by the first electrooptic crystal such as the KTN crystal 1, the cylindrical lens 21 is placed at the end as well. Fig. 3 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 4 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which the optical path includes a light source 2 such as a laser source. A beam shaper 22 is placed between the collimator 15 and the first electro-optic crystal such as the KTN crystal 1 to enhance efficiency and power handling. Fig. 4 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 5 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which the optical path includes a light source 2 such as a laser, and further a beam shaper 22 is placed between the collimator 15 and the first electro-optic crystal such as the KTN crystal 1 to change the beam shape from a circular laser beam to a horizontal ellipse and to steer the beam to be incident on the first electro-optic crystal such as a first KTN crystal 1, the latter being to cause deflection of the beam. The half wave plate 18 is to rotate the polarization through 90° a further beam shaper 23 may be placed between the first compensation lens 16 and the half wave plate 18 to rotate the elliptical beam through 90° and/or a further beam shaper 24 is placed after the second compensation lens 19 to change e the shape of the beam from elliptical to circular. These additional beam shapers enhance efficiency and power handling. Fig. 5 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 6 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in an optical path with a light source 2 such as a laser and which has a first polarizing beam splitter 25 and a first beam dump 26 placed between the collimator 15 and the first electrooptic crystal such as the KTN crystal 1 to improve the polarization, and a second polarizing beam splitter 27 and a second beam dump 28 may be placed between the half wave plate 18 and the second electro-optic crystal such as the KTN crystal 11. Introducing any optical elements in a high power beam path can create some depolarisation of the beam. To deflect a beam in an electro-optic crystal such as a KTN crystal it is best if the polarisation is as pure as possible. Wrongly polarised light will go through the electro-optic crystal unaffected and thus places a highlighting spot on an undesired location in the projected image. This can be reduced by repolarising the beam just before the first and/or second electro-optic crystals such as KTN crystals 1 and 11 as shown in Figure 6. Fig. 6 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 7 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which the optical path has a light source 2 such as a laser and a top hat beam shaper 29 is placed between the collimator 15 and a first polarizing beam splitter 25 and a first beam dump 26 which are placed between the before the first electro-optic crystal such as the KTN crystal 1 to improve the polarization, and a second polarizing beam splitter 27 and a second beam dump 28 may be placed between the half wave plate 18 and the second electro-optic crystal such as the KTN crystal 11. Introducing any optical elements in a high power beam path can create some depolarisation of the beam. To deflect a beam in an electro-optic crystal such as a KTN crystal it is best if the polarisation is as pure as possible. Fig. 7 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 8 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which there is an optical path with a light source 2 such as a laser, whereby a top hat beam shaper 29 is placed between the collimator 15 and a first polarizing beam splitter 25 and a first beam dump 26 which are placed before the first electro-optic crystal such as the KTN crystal 1 to improve the polarization, and a second polarizing beam splitter 27 and a second beam dump 28 may be placed between the half wave plate 18 and the second electro-optic crystal such as the KTN crystal 11. In addition a first cylindrical lens 17 is placed between the first compensation lens 16 and the half wave plate 18 to realign the laser beam. A second cylindrical lens 21 is placed after the second compensation lens 19. Fig. 8 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 9 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which an optical path has a light source 2 such as a laser and a beam shaper 22 is placed between the collimator 15 and the first electro-optic crystal such as the KTN crystal 1 to convert the beam shape from circular to horizontal elliptical. A further beam shaper 23 may be placed between the first compensation lens 16 and the half wave plate 18 to rotate the elliptical beam shape through 90° and/or a further beam shaper 24 is placed after the second compensation lens 19 to change the beam shape from elliptical to circular. The half wave plate 18 rotates the polarization through 90°. A first polarizing beam splitter 25 and a first beam dump 26 are placed before the first electro-optic crystal such as the KTN crystal 1 to improve the polarization, and a second polarizing beam splitter 27 and a second beam dump 28 may be placed between the half wave plate 18 and the second electro-optic crystal such as the KTN crystal 11. Fig. 9 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Figure 10 shows a modification to the optics of Figure 2 (but the same modification can be made to Figure 3 and is included within the scope and disclosure of the present invention) in which an optical path has a light source 2 such as a laser and a beam shaper 22 is placed between the collimator 15 and the first electro-optic crystal such as the KTN crystal 1 to change e the shape of the beam from circular to elliptical, and a second beam shaper 23 may be placed between the first compensation lens 16 and the half wave plate to rotate the elliptical beam shape through 90° n and/or a third beam shaper 24 is placed after the second compensation lens 19 to change the beam shape from elliptical to circular. A first polarizing beam splitter 25 and a first beam dump 26 are placed before the first electro-optic crystal such as the KTN crystal 1 to improve the polarization, and a second polarizing beam splitter 27 and a second beam dump 28 may be placed between the half wave plate 18 and the second electro-optic crystal such as the KTN crystal 11. A first cylindrical lens 17 can be placed between the first compensation leans 16 and the second beam shaper 23 and a second cylindrical lens 30 can be provided between the second compensation lens 19 and a third beam shaper 24. A third lens 31 can be provided after the third beam shaper to “rebend” the laser beam. Fig. 10 shows a beam steering unit that can be used in a highlight projector to generate highlighted parts of a projected image, e.g. an image projected by a base or image projector.

Projectors with beam steering units such as raster scanning or vector scanning units according to embodiments of the present invention make use of any of the embodiments of the present invention described with reference to Figures lb to 10 in a projector, e.g. to provide an image projector, a highlight projector for use with an image projector or in a hybrid highlight/image projector.

Figure 11 shows a lay-out for a beam steering unit such as a vector scanning or raster scanning highlighter for a projector whereby vector scanning is preferred. The projector 50 includes a light source 40 such as a laser light source which generates a light beam 42 which is incident on a beam steering unit 44 based on an electro-optic crystal such as a KTN crystal 1 and/or 11 as described with respect to any of the Figures IB to 10. The beam steering unit 44 can include one or more prisms. A beam leaving the beam steering unit 44 can be incident on a spatial light modulator 46 such as a transmissive spatial light modulator such as an LCD or a reflective spatial light modulator, e.g. a DMD or an LCOS spatial light modulator. The spatial light modulator 46 can include one or more prisms. The beam from the spatial light modulator 46 enters a projection lens system 48 for projection.

For highlighting projected videos more light needs to be directed to certain places of the projected images and hence to certain places on the spatial light modulator 46 whereas much less or little or no light should be directed to other places. What is shown in Figure 11 is preferably a projector or part of a projector that provides highlights to a projected image by beam steering a laser spot to those pixels that need highlighting. Due to lack of resolution of the electro-optic crystal such as the KTN crystal 1 or 11, a pixel may be given too much highlight. That can be corrected by the spatial light modulator 46, e.g. increasing the light that is dumped more than is required by the base or image projector. If too little light is steered towards a pixel then this can again be corrected by operation of the spatial light modulator 46, i.e. less light is dumped by the spatial light modulator 46 than is required by the base or image projector.

Embodiments of the present invention include a projector with

1) the full dynamic range of intensity at each pixel modulated according to an image content (i.e as part of a main or base projector), or

2) the dynamic range is separated in a base light and a highlight. The base light operates as a traditional projector, i.e. projecting conventional video images. The highlight operates only to provide highlighted parts of the image projected by the base or main projector. The highlighter projector can be provided by holographic, two stage amplitude modulated or rasterized or vectorized beam scanning light path.

Images of a projector 50 are shown in Figure 12. On the left is shown the image to be projected. This image is dark except for bright portions on the string adjusting knobs. Similarly a night scene of a fire would also generate dark parts with brightly illuminated areas, e.g. of flames. These bright portions are enhanced by highlighting according to embodiments of the present invention. Hence there is a projected base image using a conventional projector. To enhance the base images a highlighter is used to generate highlight images to be superimposed on the conventional projected base images and to provide a greater light intensity at the highlight positions. For vector scanning by such a highlighter projector, the highlighted image is decomposed into discrete spots shown schematically in Figure 12 in the middle. Using beam steering, the laser light of the highlighter projector can be vectored to any of these highlighted positions based on the voltages applied to tandem electro-optic crystals such as KTN crystals as described with reference to any of Figures lb to 10. The spots are blurred in Figure 12 as the highlight images do not need to be sharply in focus and generally lack resolution. The cleaning up of the image can be performed by a spatial light modulator 46. This modulator will direct the highlight to a dump where some more or less light is dumped, relating to places of an image where the highlighted image has an intensity that does not match with the correct image which is shown on the right in Figure 12 as an amplitude modulated image. The clean-up of the highlighted image is done via a software prediction in combination with calibration on test patterns. The correction is done by the spatial light modulator 46 which corrects pixels that are too bright. A pixel which is too dark should be very rare and does not need correction as the desired image is split into a base and a highlight part. The highlight part can be selected such that there is always enough light to create the highlights, and dark pixels should not appear. In case dark pixels do appear, they will be in the darkest part of the highlights and it will not harm the image.

If there is clearly not enough light for the highlights then it is also possible to scale down all the highlights.

A particular advantage of any of the electro-optic beam steering units as described with reference to any of Figures lb to 10, is that the electrical values that need to be applied to the electro-optic crystal such as the KTN crystal 1 or 11 to vector the light beam to a certain pixel can be determined in advance. Also the size of the spot generated by the laser can also be determined in advance. This means that the light intensity patterns shown in the centre image of Figure 12 can be predicted in advance and hence also bright pixels which should be dark can be determined and the spatial light modulator 46 can be driven to dump these over-bright pixels resulting in the sharp image on the right of Figure 12. Thus the voltages to be applied to the electro-optic crystals such as the KTN crystals 1 or 11 can be stored in a Look Up Table and can be retrieved very quickly.

As shown schematically in Figure 13A in an optical subunit of a projector 60 separate coloured laser sources such as primary colour sources as separate red, green and blue (RGB) light sources 61, 62, 63 emit coloured laser beams and each colored beam passes through its own beam steering unit 64, 65, 66 respectively of the kind described with respect to any of the Figures IB to 10. Coloured light beams from the beam steering units 64-66 are combined in a combiner (not shown) and sent to a single transmissive or reflective spatial light modulator 67 such as an LCD, DMD or LCOS to be sent then to a projection lens system (not shown).

As shown schematically in Figure 13B in an optical subunit of a projector 60 separate coloured laser sources like primary colour sources such as separate red, green and blue (RGB) light sources 61, 62, 63 emit coloured laser beams and each colored beam passes through its own beam steering unit 64, 65, 66 respectively of the kind described with respect to any of the Figures IB to 10. Coloured light beams from the beam steering units 64-66 are each sent to a transmissive or reflective spatial light modulator 67, 68, 69 respectively such as an LCD, DMD or LCOS and afterwards combined in a combiner 71 to be sent then to a projection lens system (not shown).

As shown schematically in Figure 14 in an optical subunit of a projector 70 a white light laser source 72 emits a white laser beam to a beam steering unit 74 of the kind described with respect to any of the Figures lb to 10. The light beam from the beam steering unit 74 is split in a splitter 75 into three separate colour light beams like primary colour beams such as red green and blue light beams and each coloured light beam is sent to its own transmissive or reflective spatial light modulator 76, 77, 78, respectively such as an LCD, DMD or LCOS to be sent then to a projection lens system (not shown). The transmissive or reflective spatial light modulators 76, 77, 78 are synchronized with the operation of the voltage control of the beam steering unit 74 so that the correct coloured or white spots are directed to the correct part of the image when projected.

As shown schematically in Figure 15A in an optical subunit of a projector 80 separate coloured laser sources like primary colour sources such as separate red, green and blue (RGB) light sources 81, 82, 83 emit coloured laser beams and each colored beam passes through its own beam steering unit 84, 85, 86 respectively of the kind described with respect to any of the Figures IB to 10. Coloured light beams from the beam steering units 84-86 are then projected directly onto a projection screen 87. In this projector 80 there are not two different projectors - a conventional one and a highlighter. Instead the beam steering units 84 to 86 provide the full image.

As shown schematically in Figure 15B in an optical subunit of a projector 90 an infrared laser source 92 emits an infrared laser beam to a beam steering unit 94 of the kind described with respect to any of the Figures IB to 10. The light beam from the beam steering unit 94 is upconverted in an upconveter 95 to three separate colour light beams like primary colour beams such as red green and blue light beams via one or more wavelength conversion devices such as a phosphors or non-linear crystals. Each coloured light beam is sent to its own transmissive or reflective spatial light modulator 96, 97, 98, respectively such as an LCD, DMD or LCOS to be sent then to a projection lens system (not shown).

Embodiments of the present invention provide base and highlight projector options using any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13A, or B to 15 A, or B. An embodiment of the present invention includes a dual and highlight projector or separate base and highlight projectors in which the base and highlight exiting a projection lens system is combined on the screen into a video image with highlighting. Figure 16 shows a base projector 100 for projecting video images in a conventional way, a highlight projector 101 and these two projectors are aligned so that parts of the image projected onto the screen 102 by the base projector 100 are highlighted with light from projector 101. Projector 101 comprises any of the beam steering units described in any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13A, orBto 15 A, orB.

An embodiment of the present invention includes a dual base and highlight projector using any of the beam steering units described in any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B in which the highlight and base light beams are combined via polarisation before or after the spatial light modulator(s) such as the transmissive or reflective spatial light modulator(s) (see Figures 17 to 19). Figure 17 shows a primary colour laser 103a such as a red laser which emits coloured laser light to a beam steering unit 104 as described with respect to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B, or 15 A, or B. The light from the laser 103a is used for highlighting. The light from the beam steering unit 104 is incident on a polarization beam splitter/combiner 105. A primary colour laser 103b such as a red laser emits coloured laser light to uniformizing optics 106 such as one or more integrators, one or more diffusers which are optionally moving and from there to the polarization beam splitter/combiner 105 where the beam from laser 103a is combined with the beam from laser 103b via polarization. The light from the laser 103b is used to provide the base image which is combined with the highlight image to form combined beams. The combined beams are then incident on a transmissive or reflective spatial light modulator 107, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 103a, 103b respectively and the three coloured beams are combined in combiner 108 to be sent then to a projection lens system 109. This structure is repeated for each other primary colour red, green, blue etc.

Figure 18 shows a primary colour laser 110a such as a red laser which emits coloured laser light to a beam steering unit 111 as described with respect to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15 A, or B. The light from the beam steering unit Illis incident on a transmissive or reflective spatial light modulator 112, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 110a and the three coloured beams are combined in combiner 113. A primary colour laser 110b such as a red laser emits coloured laser light to uniformizing optics 114 such as an integrator and from there to a transmissive or reflective spatial light modulator 115, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 110b and the three coloured beams are combined in combiner 116. Light from the two combiners 113 and 116 is incident on a polarization beam splitter/combiner 117 where the beam from laser 110a is combined with the beam from laser 110b via polarization to be sent then to a projection lens system 118.

Figure 19 shows a primary colour laser 120a such as a red laser which emits coloured laser light to a beam steering unit 121 as described with respect to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15A, or B. The light from the light beam 120a is used to provide highlights to a base image. The light from the beam steering unit 121 is incident on a transmissive or reflective spatial light modulator 122 which preserves the polarization of the light beam, such as an LCD, DMD or LCOS. A primary colour laser 120b such as a red laser emits coloured laser light to uniformizing optics 123 such as an integrator and from there to a transmissive or reflective spatial light modulator 124, such as an LCD, DMD or LCOS. The light from the laser 120b is used for producing a base image. Light from the two transmissive or reflective spatial light modulators is incident on a polarization beam splitter/combiner 125 where the beam from laser 120a is combined with the beam from laser 120b via polarization. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 120a and 120b respectively and the three coloured beams are combined in combiner 126 to be sent then to a projection lens system 127.

Embodiments of the present invention includes a dual base and highlight projector using any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B in which the highlight and base light beams are combined via spectral multiplexing before or after the spatial light modulator(s) such as the transmissive or reflective spatial light modulator(s) (see Figures 20 to 22).

Figure 20 shows a primary colour laser 130a such as a red laser which emits coloured laser light to a beam steering unit 131 as described with respect to any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15A, or B. The light from the beam steering unit 131 is incident on a dichroic combiner 132. A primary colour laser 130b such as a red laser emits coloured laser light to uniformizing optics 133 such as an integrator and from there to the dichroic combiner 132 where the beam from laser 130a is combined with the beam from laser 130b via spectral multiplexing. The combined beams are then incident on a transmissive or reflective spatial light modulator 134, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 130a, 130b respectively and the three coloured beams are combined in combiner 135 to be sent then to a projection lens system 136.

Figure 21 shows a primary colour laser 140a such as a red laser of a highlight path which emits coloured laser light to a beam steering unit 141 as described with respect to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B, or 15 A, or B. The light from the beam steering unit 141 is incident on a transmissive or reflective spatial light modulator 142 such as an LCD, DMD or LCOS. A primary colour laser 140b such as a red laser of a base image path emits coloured laser light to uniformizing optics 143 such as an integrator and from there to a transmissive or reflective spatial light modulator 144, such as an LCD, DMD or LCOS. Light from the two transmissive or reflective spatial light modulators 142, 144 is incident on a dichroic combiner 145 where the beam from laser 140a is combined with the beam from laser 140b via spectral multiplexing. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 140a and 140b respectively and the three coloured beams are combined in combiner 146 to be sent then to a projection lens system 147.

Figure 22 shows a primary colour laser 150a of a highlight path such as a red laser which emits coloured laser light to a beam steering unit 151 as described with respect to any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13 A, orB, or 15 A, or B. The light from the beam steering unit 151 is incident on a transmissive or reflective spatial light modulator 152 such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 150a respectively and the three coloured beams are combined in combiner 153. A primary colour laser 150b of a base image path such as a red laser emits coloured laser light to uniformizing optics 154 such as an integrator and from there to a transmissive or reflective spatial light modulator 155, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 150b respectively and the three coloured beams are combined in combiner 156. Light from the two combiners 153, 156 is incident on a dichroic combiner 157 where the beam from laser 150a is combined with the beam from laser 150b via spectral multiplexing to be sent then to a projection lens system 158.

Embodiments of the present invention include a dual base and highlight projector using any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B in which the highlight and base light beams are combined via time multiplexing before or after the spatial light modulator(s) such as the transmissive or reflective spatial light modulator(s) (see Figures 23 to 25).

Figure 23 shows a primary colour laser 160a such as a red laser which emits coloured laser light to a beam steering unit 161 as described with respect to any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15A, or B. The light from the beam steering unit 161 is incident on a time based switching module 163. A primary colour laser 160b such as a red laser emits coloured laser light to uniformizing optics 162 such as an integrator and from there to the time based switching module 163 where the beam from laser 160a is combined with the beam from laser 160b on a time switching basis. The combined beams are then incident on a transmissive or reflective spatial light modulator 164, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 160a, 160b respectively and the three coloured beams are combined in combiner 165 to be sent then to a projection lens system 166.

Figure 24 shows a primary colour laser 170a such as a red laser which emits coloured laser light to a beam steering unit 171 as described with respect to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15A, or B. The light from the beam steering unit 171 is incident on a transmissive or reflective spatial light modulator 172 such as an LCD, DMD or LCOS. A primary colour laser 170b such as a red laser emits coloured laser light to uniformizing optics 173 such as an integrator and from there to a transmissive or reflective spatial light modulator 174, such as an LCD, DMD or LCOS.

Light from the two transmissive or reflective spatial light modulators 172, 174 is incident on a time based switching module 175 where the beam from laser 170a is combined with the beam from laser 170b via switching in time. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 170a and 170b respectively and the three coloured beams are combined in combiner 176 to be sent then to a projection lens system 177.

Figure 25 shows a primary colour laser 180a such as a red laser which emits coloured laser light to a beam steering unit 181 as described with respect to any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13A, or B, or 15A, or B. The light from the beam steering unit 181 is incident on a transmissive or reflective spatial light modulator 182 such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 180a respectively and the three coloured beams are combined in combiner 183. A primary colour laser 180b such as a red laser emits coloured laser light to uniformizing optics 184 such as an integrator and from there to a transmissive or reflective spatial light modulator 185, such as an LCD, DMD or LCOS. The other primary colours such as the other two primary colours green and blue are generated by further primary colour lasers such as green and blue lasers and similar optics as for the red laser 180b respectively and the three coloured beams are combined in combiner 186. Light from the two combiners 183, 186 is incident on a time based switching module 187 where the beam from laser 180a is combined with the beam from laser 180b via time based switching to be sent then to a projection lens system 188.

In the above embodiments if the combining is done before the spatial light modulator a single spatial light modulator can be used whereas if the combining is done after the spatial light modulator two spatial light modulators can be used. These disclose further embodiments of the present invention.

An embodiment of the present invention includes a dual base and highlight projector using any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B in which the highlight and base light beams are combined by sending the highlight beam via an angle into the base beam path (etendue combination - see Figure 26). Figure 26 shows coloured base light from a base light projector being combined with coloured light from a highlight projector comprising any of the beam steering units described in any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B at an angle combined via etendue. The combined beam is then sent to the projection lens system.

A further embodiment of the present invention includes a dual base and highlight projector using any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B in which the highlight and base light beams are combined via a pinhole mirror before the spatial light modulator.

In any of the embodiments of the present invention e.g. as described with reference to any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13A, or B to 15A, or B or projectors shown in Figures 16 to 26, a varifocal lens can be added in the beam path. In particular, a varifocal lens can be added after the electro-optic crystal such as the KTN crystal or after photonic deflector unit to adjust the beam spot size in real time. In particular, a variofocal lens can be placed between the electro-optic crystal and the transmissive or reflective spatial light modulator such as an LCD, DMD or LCOS as part of any of the beam steering units described in any of the Figures IB to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15A, or B, or projectors of Figures 16 to 26.

In the electro-optic crystals used in any of the embodiments of the present invention the generation of birefringence in optical materials is achieved via either the Pockel or the Kerr or Pockel effect. The Pockel effect is a linear in the electric field while the Kerr or Pockel effect is quadratic. These cells are typically used as variable waveplates. Kerr/Pockel cells are traditionally used as pure capacitors and thus insulators. This means that the birefringent effect is uniform through the crystal (no GRIN effect). An electro-optic crystal such as a KTN cell used in any of the embodiments of the present invention is preferably driven at a specific temperature, e.g. close to Curie temperature, that allows for electrons to penetrate into the crystal. The crystal operates in the so-called trapped-space-charge regime (see “Electro-optic KTN devices” - Yagi Shogo 2014). This is a variant of the Kerr or Pockel effect which is linear in the electric field and generates large optical effects.

Electro-optic crystals such as KTN cells according to any of the embodiments of the present invention can be driven and modelled as a capacitor even though the space charges introduce resistive effects. A DC-voltage from a DC source is applied to “charge” the crystal with electrons. This generates a default DC deflection angle and a default beam deformation. The optics provided in accordance with embodiments of the present invention is adapted to compensate the DC beam deformation for a single calibrated DC value. Superimposed on the DC drive signal a varying signal such as an AC signal can be applied. This AC signal can be sinusoidal and in resonance which allows to move charges very fast (e.g. order 700 kHz) and is suitable for raster scanning in any of the embodiments of the present invention. The embodiments of the present invention are preferably driven to perform vector scanning with which the AC signal is essentially a series of step voltages chosen to steer the laser beam to match the positions or desired coordinates of the highlights. To achieve fast spot displacement, amplifiers with high voltage (+/- a few 100V), high slew rate (a few 100V/ps) and high current (a few 100mA) are preferred. The frequencies achieved can be 10-50 kHz.

An example of a driving circuit with DC offset for use with embodiments of the present invention is a driving circuit with a DC offset e.g. in the range 0 to plus or minus 250 Volt such as 100 Volt and a superimposed AC voltage such as an AC voltage with a maximum of +/- 250V as shown in Figure 27. The wave form comprises small steps being transient for 1 to 5 micro sec or 10 microsec, or up to 25 microsec or up to 400 microsec.

Applying step voltages in arbitrary order with amplitudes related to image content does not guarantee a zero volt average of the pulses. Realistically on a frame by frame base the average will always differ from zero volts. A non-zero average can cause a virtual rise of the DC level combined with electron drift. A minimum frequency 100Hz can be able to eliminate electron drift. Embodiments of the present invention can be driven to keep the average applied voltage equal to zero volts. An alternative to control the application to compensate for the changing DC level. The DC drift can be determined by:

• Measuring the drift with an electronic integrator circuit and ADC converters.

• Compute it directly in the software that computes the highlight locations • Monitor the output spot with an imaging device such as a CMOS or CCD camera and adjust accordingly.

DC drift is a problem that occurs when the pulses send to the crystal don’t average to 0V. Any of the embodiments of the present invention can use:

• Blanking of the laser during compensation • Compensation by placing the laser on the aperture • Use multiple crystals so one crystal is “reset” while using the other(s).

Any of the embodiments of the present invention can use DC balancing which means that the integral of applied voltage over a certain time is made to be zero. By blanking out the laser at the source any compensation voltage can be applied as no laser beam hits the electro-optic crystal and disturbance to the projected image will occur. A high balancing voltage can be set for a short time or a lower balancing voltage for a longer time.

If the laser cannot be blanked out the laser can be set outside the relevant area e.g. onto the aperture surrounding the transmissive or reflective spatial light modulator such as an LCD, LCOS or DMD and moved around to balance the DC voltage.

In case of multiple electro-optic crystals such as KTN crystals per color, one crystal can be reset to zero while another illuminates the transmissive or reflective spatial light modulator such as an LCD, LCOS or DMD. Switching crystals frame per frame allows for balancing. The control software can also arrange the spots such that an optimised time spreading of the voltages is achieved.

Any of the embodiments of the present invention can split each drive pulse in two, so that each plus has one up and one down flank, in order to have pure AC that guarantees a zero volt average as shown schematically in Figures 28A and 28B. Sending an AC pulse from a laser 192 to an electro-optic crystal such as a KTN cell 194 instead of a DC pulse means that instead of one spot there is always two spots 195, 197, one at the desired position and one at a position diametrically opposite which is undesired. Assuming one dumps the second side then 50% of the light is lost as the undesired spots contain half of the total energy. It is thus important to recuperate this light. This can be done by mirrors or by a special lens as described below. It is preferred if the undesired spots which contain half of the total energy can have that energy recuperated. This can be done by mirrors or by a special lens, for example.

Figures 29A and B show embodiments of the present invention which make use of a mirror. Figure 29A shows a flat mirror 190 that reflects the light 195 from the laser 192 from the moment the light exits the electro-optic crystal such as a KTN cell 194. This configuration places the up (197) and down laser spot (195) on top of each other. Figure 29B shows a curved mirror 196 that reflects the light from the laser 192 at a distance from the electrooptic crystal such as a KTN cell 194. This configuration also places the up (195) and down laser spots (197) on top of each other.

Figure 29 C shows a lens 198 that deflects the light coming from the laser 192 and exiting the the electro-optic crystal such as a KTN cell 194 in the bottom part 195 and passes the light to the top part 197. The deflection is such that the bottom spot arrives at the same location as the top spot. A 3D layout of such a lens that compensates bottom to top and right to left is shown schematically in Figure 29D.

Any of the embodiments of the present invention can use DC compensation such that the optics following the electro-optic crystal such as the KTN crystal will be adapted according to the DC level.

Any of the embodiments of the present invention can use any of the following options.

Option 1:

calibrate a varifocal lens to compensate for different DC levels. This allows for real time shape optimisation. A variofocal lens can be used with any of the embodiments of the present invention placed after the electro-optic crystal.

Option 2:

Characterise the spot shape for different spot shapes and adjust the transmissive or reflective spatial light modulator such as a DMD, LCOS, LCD.

Any of the embodiments of the present invention can use any of the following options for power handling.

Option 1: beam reshaping

An electro-optic crystal such as a KTN crystal typically has a rectangular entrance window with about a 3 tol aspect ratio. An incident circular laser beam can thus at most have a 1mm diameter, leaving a large part of the crystal unused. If a high laser power needs to be passed through the electro-optic crystal any of the embodiments of the present invention can make use of beam reshaping. In any of the embodiments of the present invention the incident laser beam can be reshaped to an ellipse and thus a beam can be passed with about 3 times lower optical density or a three times more powerful beam can be put through the same electro-optic crystal.

In any of the embodiments of the present invention the following optical transitions can be done:

From a circular laser beam to a horizontal ellipse, incidence on the first electro-optic crystal such as a first KTN crystal to cause deflection of the beam. Rotate polarization of the laser beam through 90°. Reshape beam to a vertical ellipse, incidence on the second electrooptic crystal such as a second KTN crystal to cause deflection of the laser beam along an orthogonal direction. Finally the laser beam is reshaped to a circle.

The use of beam shaping improves the maximum deflection angle an electro-optic crystal such as a KTN crystal can generate because the optical power density of the laser is utilized better.

Option 2: Tophat/flat-top shaping.

With known optical components a Gaussian laser beam can be transformed into a tophat shaped beam. In contrast with a Gaussian beam the tophat beam does not have long tails that broaden the actual beam beyond the beam waist. The tails of a Gaussian beam contain about 14% of the energy. This energy is lost if the beam needs to be clipped or generates undesired diffraction if there is interaction with the sides of the electro-optic crystal. Use of the tophat beam shape improves the maximum deflection angle an electro-optic crystal such as a KTN crystal can generate because the optical power density of the laser is utilized better.

Option 3: cascading

When larger crystals are used, more light is allowed to pass through but the electric field diminishes for a fixed voltage. If a large deflection angle is required the electric field will no longer suffice. This can be solved by cascading multiple KTN crystals in series to accumulate deflection.

Use of cascading improves the maximum deflection angle a series of electro-optic crystals such as a KTN crystals can generate because the optical power density of the laser is spread over several crystals.

Option 4:

The required laser power can be distributed over multiple electro-optic crystals placed in parallel such that each crystal is driven below a certain threshold. Parallel beams allows for parallel addressing of the highlights.

Sub-option 1:

The target plane of the transmissive or spatial light modulator can be divided in a number of areas equal to the number of laser beams. Each beam then addresses its own area. This allows for smaller deflection angles, parallelisation of the software and higher resolution highlighting as each crystal can generate a fixed number of spots so that is there are more crystals there are more spots but with lower power per spot.

Sub-option 2:

Each beam can address the full plane. This has the same increased resolution as option 1. If a very bright highlight is needed in one place the energy can be spread over time more easily because each spot has lower intensity. This is also very beneficial for eye safety.

Option 5:

If the power is distributed over parallel beams there is also an option to do wavelength broadening. If each beam is generated with a slightly different wavelength a more broad spectral line is achieved. This is very beneficial for despeckling of an image. In this case all beams have the same spot pattern to conserve color uniformity across the image.

In any of the embodiments of the present invention means for laser safety for scanning lasers can be provided. For example:

• A vector scanned projection system can be regarded as a pulsed laser source. Pulsed lasers have high intensity in a short time with a certain repetition rate. One such pulse is already sufficient to induce eye damage.

A vector scanner for movie purposes with one deflector per color should be operated with keep out zones, supervision by safety officers, warning signs, ....

Note: the blinking reflex is 0.25s while one pulse is 0.0001s (l-100ps) with a rise time of 0.00001s (l-10ps). The eye is thus always slower.

To make the product more eye safe the pulses should be made low intensity, i.e. Energy per area per time.

The highlighting can be provided over large zones instead of very few pixels which will reduce the energy per area.

Distributing the power over multiple photonic beam steering units and address pixels/zones at different times so that energy per time is reduced.

Embodiments of the present invention can use an RGB system with three electro-optic crystal or KTN crystal beam steering unit deflectors or alternative a white laser system can be used with one beam steering unit deflector.

The advantages of white laser can be:

• Less electro-optic crystal such as KTN deflectors is more economical • One deflector requires less alignment

Disadvantages:

Hard to find white laser (e.g. supercontinuum lasers)

The deflection angle of the beam steering unit is wavelength dependent, i.e. there is chromatic dispersion) which can create rainbow effects.

Less saturated colors can be used.

However, these rainbows can be masked if each color has a separate transmissive or reflective spatial light modulator. The rainbow effect can be reduced with compensation crystals

The quality of an electro-optic crystal such as a KTN crystal vectorscanner can be judged by the number, N, of resolvable spots. It is good to have 5<N<10, better is 10<N<20, or 20<N<100 or 100<N is the best. This translates to beam quality M2 dependent on the max beam diameter D, the max deflection angle of the electro-optic crystal such as the KTN crystal (0m) and the used wavelength (λ).

dm rr—D

M2 = —= (is equal to or approximately equal to) 2.95

4Z

This value must be greater than 1, e.g. such as in the range 1 to 10.

For single pass electro-optic crystal the full deflection angle is currently specified at

40mrad.

The max beam diameter D is related to the shortest length W of electro-optic crystal such as the KTN crystal for example D =W-0.5mm.

An electro-optic crystal such as a KTN crystal has a small entrance window (for example 1-3mm x 3mm) with 40mrad deflection for a single pass configuration. A triple pass configuration has 160mrad deflection but is more constraining for the laser diameter. Example, take a single pass crystal with 40mrad max deflection, 1mm x 3mm entrance window and a green laser with k=532nm laser. If a resolution of 10 separable highlight spots is required in the longest direction of the image, this means that the divergence angle of the laser is max 0=4mrad full angle (40mrad/10 highlights). The laser diameter can be at most D=0.5mm to pass through the crystal. The required laser quality M2 is given by:

M2 =—=2.95

4λ

If M2=l this is a perfect Gaussian laser, so closer to 1 is closer to a Gaussian laser. The range may be larger than up to less than 10) is a good laser.

Values of M2 for different laser types (power >10 Watt):

Fiber pumped laser =1.1-1.2

Direct diode >10

Fiber coupled diode >80

DPSS ((diode pumped solid state) >3

An electro-optic crystal such as a KTN crystal has a very large efficiency (e.g. >95%). Thanks to this high efficiency the generation of highlights can be done with reasonable laser powers.

Example 1:

Requirement is a 2001umen LCOS cinema highlighter projector. Assume 40% efficiency for the LCOS and projection lens. Assume 75% for the electro-optic crystal such as the KTN crystal and associated optics.

Red laser = 1.25W / Green laser = 0.86W / Blue laser = 1.07W

Example 2:

A 40001umen LCOS cinema highlighter projector is required.

Assume 40% efficiency for the LCOS and projection lens.

Assume 60% for the electro-optic crystal such as the KTN crystal and associated optics.

Red laser = 31W / Green laser = 21W / Blue laser = 18W

With respect to the use of infrared lasers it is known that the electro-optic crystal such as the KTN crystal loses efficiency rapidly in the 400-500nm range. Given that blue light for the Rec2020 standard is 467nm, a problem can arise to get the blue laser through the electro-optic crystal in a clean and effective way. The deflection might be very small in blue.

In any of the embodiments of the present invention an alternative is to use a high power IR laser to transmit light through the electro-optic crystal such as the KTN crystal. Once the IR beam has passed through the electro-optic crystals such as the KTN crystals it should be transformed into the required colour, e.g. R, G or B). This is an upconverting (antiStokes) process, meaning that each photon of RGB has more energy than the original IR photon. Because of this upconversion is not efficient (e.g. 10% max).

Nonlinear crystals can be used for frequency conversion of lasers, e.g. placed after a beam steering unit according to any of the embodiments of the present invention as described in any of the Figures lb to 10 and/or any of the optical sub-units of Figures 13 A, or B to 15 A, or B or any of the projectors described with reference to Figures 16 to 26.

Electro-optic, photorefractive crystal examples:

The vector/pulse nature of the highlights as produced by any of the embodiments of the present invention can interfere with an amplitude modulator such as a transmissive or reflective spatial light modulator, e.g. LCOS, LCD, DMD.

Option 1:

Syncronisation of the pulse locations with the digital PWM signals of the amplitude modulator.

Option 2:

An LCOS or LCD can be driven with analog signals instead of digital PWM. Also the system can have instant full plane update instead of line update. Such an analog system is not time dependent and will not interfere with the pulses/spots.

A software algorithm 200 to be used with any of the embodiments of the present invention is shown schematically in Figure 30. The software can be run on a projector controller, e.g. having a processing engine such as a microprocessor or an ASIC or an FPGA or similar. Algorithm 200 comprises the steps:

Step 202: Load video frame

Step 203 Find highlight maximum

Step 204: Subtract highlight from frame and continue with steps 203 and 204 while number of highlights is < N and while number of iterations <M.

Step 205: store coordinate of highlight

Step 206: compute masking pattern

Step 207: generate spots.

The Software algorithm is able to find the highlight locations in the projected image via

Option 1:

• Divide the video frame into many small non-overlapping segments and determine for each segment whether or not a highlight is required • If required the highlight is place centrally in the segment • Subtract the highlight for each required segment • Repeat the above

Or via Option 2:

• Divide the frame into many small non-overlapping segments • Determine for a segment if a highlight is required • Subtract the highlight on its exact spot for this segment • Move to the next segment

Or via Option 3:

• Divide the frame into many small non-overlapping segments • Determine for a segment if a highlight is required • Subtract the highlight on its exact spot for this segment • If a highlight was found, repeat the same segment • If not, move to the next segment highlight

Options 2 and 3 are preferred.

In the options presented above the segments are non-overlapping but a highlight can still be in multiple segments. This means that segment 2 cannot be computed before segment 1 has been computed and parallelizing the code is restricted.

An image can be broken up into a checquerboard pattern such as a red green and blue chequerboard pattern comprising distributed segments in each of the three primary colours. Parallel computing can be done by skipping an intermediate segment or intermediate segments whereby each color can be done in parallel, e.g. all green in parallel. Hence the green, blue and red segments do not have an adjacent segment in the same colour. Parallel computing can be performed on multithreaded RAM, GPU or dedicated FPGA.

Despeckling can be achieved in any of the embodiments of the present invention by using multi-wavelengths, depolarization, diffusing or electronic diffusing by vibration or any combination of these

Efficiency increase is important for a highlighter. The crucial, controllable, component that determines the efficiency is the “first spatial light modulator”. In case of a DMD the efficiency is about 70% efficiency (not considering additional optics). In case of an LCOS it is about 85% efficiency (not considering additional optics). In case of an electro-optic crystal such as a KTN crystal the efficiency in the visible range >95%. With at least two in series, the efficiency is about 90%.

A second aspect is how light is used. In embodiments of the present invention zone to zone mapping is not required so that if only a small highlight is needed all other zones do not need to be blacked out.

Embodiments of the present invention can use all to all mapping and then if only a small highlight is needed all light can be directed to that highlight creating a very bright highlight with no light being dumped

Further because the electro-optic crystal such as the KTN crystal requires very collimated lasers there is also minimal loss from aperturing the light.

Embodiments of the present invention provide a mechanical fixation of the electro-optic crystal such as a KTN crystal, e.g. to allow the cell to vibrate with reduced possibility of breaking or without breaking. Allowing an increase in vibrational energy has been found to affect operation by allowing the temperature of the crystal to be set closer to the Curie temperature. It has been found that operating with such temperatures gives larger deflection angles but the vibrations increase with increasing deflection angle.

The mechanical fixation has to fulfill one or more or all of three functions:

• Allow large vibrations of the crystal without causing high stresses in or on the crystal material • Allow good temperature control of the crystal: no temperature gradients in the crystal and regulation to tight tolerances such as less than 1°C, less than 0.5°C preferably to 0.1 °C or less.

• Allow good electrical contact to the electrodes of the crystal.

The temperature control and electrical control can be via one material or via two materials. Embodiments using these materials are viable but using two materials can provide more advantages than using one material.

In all figures copper can be replaced by other good electrical conductors such as gold, silver, or aluminium.

Figure 33 shows a schematic presentation of a highlighter projector 500 as a standalone item for one colour. It can be used with a normal image projector whereby the images from the highlighter projector have to be aligned with the images from the base or image projector on a projection screen. Alternatively the projector of Figure 33 may be merged with any image or base projector as explained with respect the above embodiments which are incorporated herewith as amendments to the projector of Figure 33. A laser 502 of e.g. one primary colour emits a beam 501 to a collimator 504 and then to a first electro-optical crystal such as a KTN crystal 510. The crystal 510 is adapted to steer the beam 501 in response to a signal from a signal generator 512 being applied to the electro-optical crystal such as the KTN crystal 510. The steering isa deflection in a first direction. The signal generator 512 can be controlled by a digital processing device such as a computer 514. An amplifier 506 can be provided to amplify the signal from the signal generator. The temperature of the electro-optical crystal such as the KTN crystal 510 is controlled by means of a temperature control subsystem 508 which may include means for heating and/or cooling such as a resistor heater/Peltier cooler which is preferably controlled by a controller such as a microcontroller or by the processing device 514.The steered beam 501 exiting the electro-optical crystal such as the KTN crystal 510 is incident on a waveplate 518 which alters the polarization of the beam.

The beam 501 exiting the wave plate 518 is incident on a second electro-optical crystal such as a KTN crystal 520. The crystal 520 is adapted to steer the beam 501 by application of a signal from another signal generator or from the signal generator 512. The other signal generator or the signal generator 512 can be controlled by the digital processing device such as the computer 514. An amplifier 516 can be provided to amplify the signal from the signal generator. The temperature of the electro-optical crystal such as the KTN crystal 520 is controlled by means of a temperature control subsystem 519 which may include means for heating and/or cooling such as a resistor heater/Peltier cooler which is preferably controlled by a controller such as a microcontroller or by the processing device 514. The steered beam 50 leaving the second electro-optical crystal such as a KTN crystal 520 is also steered by the second electro-optical crystal such as a KTN crystal 520 and is deflected in a second direction perpendicular to the first direction so that the beam can reach any part of a 2 dimensional area by application by appropriate signals from the signal generator 512. The beam 501 from the second electro-optical crystal such as a KTN crystal 520 can be incident on a diffuser 522 which can optionally be movable, e.g. oscillating, which can reduce speckle. The beam501 leaving the diffuser 522 is incident on relay optics 524 and from there to a spatial light modulator 526, e.g. a reflective spatial light modulator such as a DMD or LCOS. In a three colour projector the optical path described above is repeated for two other primary colours and the three images from spatial light modulators are combined in a combiner 528 and from there are sent to a projection lens 530.

A controller such as the processing device 514 with or without controller 508, 509 can be adapted to provide highlighting for a projector. The projector can comprise a first laser light source 502 emitting a laser beam 501 incident on a first electro-optic crystal 510 exhibiting the Kerr or Pockel effect, passing through a half-wave plate 518 and being incident on a second electro-optic crystal 520 exhibiting the Kerr or Pockel effect and the beam 501 emerging from the second electro-optic crystal 520 exhibiting the Kerr or Pockel effect is directed through at least one optical component such as diffuser 522 and relay optics 524 towards a 2D projection screen e.g. via a projection lens 530 and/or a colour combiner 528, the controller comprising first and second means 506, 516 for controlling the application of voltages to the first electro-optic crystal 510 exhibiting the Kerr or Pockel effect and the second electro-optic crystal 520 exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot to be directed to any position on the 2D projection screen.

The controller can also be used with a separate projector for projecting image, or a second optical path along which the projected image is processed and projected and displayed. The beam leaving the electro-optic crystal 520 is incident on a spatial light modulator 526 such as a DMD or LCOS device and the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the controller is adapted to drive the spatial light modulator to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

The controller can also have a unit to generate voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel and the controller can be adapted to drive the unit to keep the average applied voltage equal to zero volts.

The controller may also have means for compensating for a changing DC voltage level.

The controller may have means for determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly

The controller may be adapted for:

Blanking of the beam from the first laser source during compensation, or

Compensating by placing the first laser source on the aperture, or

The controller may have:

The controller can have means for finding a highlight location in the projected image which is adapted to:

The controller can have the means to find a highlight location in the projected image which is adapted to:

divide the video frame into many small non-overlapping segments, determine for a segment if a highlight is required, subtract the highlight on its exact spot for this segment, and move to the next segment and repeat above steps.

The controller can have means to find a highlight location in the projected image which is adapted to:

divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment if a highlight has been found, repeat for the same segment.

The embodiment of Figure 31A uses a soft, elastic material 302 with good thermal conductivity and being an electric insulator to surround and support the electro-optic crystal such as a KTN crystal 311. An example of the soft material is a gel/silicone/ foam. The contacts 304, 306 to the electro-optic crystal such as a KTN crystal 311 are preferably elastic or flexible, e.g. provided by springs, or “loose wires”. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 3 IB uses a soft, elastic material 302 with good thermal conductivity and being an electric insulator to surround and support the electro-optic crystal such as a KTN crystal 311. An example is a gel/silicone/ foam. The contacts 301, 303 to the electro-optic crystal such as a KTN crystal 311 are preferably copper plate electrical connections having a sinusoidal or wave like structure. This provides good support to the electro-optic crystal such as a KTN crystal 311. Copper can be replaced by other good electrical conductors. The waves act as springs to dampen vibrations of the the electro-optic crystal such as a KTN crystal 311. Surfaces 307, 308 (not shown) of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 31C uses the same materials as in Figure 3 IB but a forced gas flow 309 is used to control temperature. It is preferred but not essential to use inert gasses such as Nitrogen or Argon. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 3 ID uses the forced gas flow 309 of Figure 31C to control temperature. It is preferred but not essential to use inert gasses such as Nitrogen or Argon. Electrical contact is provided by copper plates 401, 403 which are fixed (e.g. with glue, solder, welding, etc.) to the crystal 311 to provide structural support and electrical contact. Copper can be replaced by other good electrical conductors. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 3 IE uses the forced gas flow 309 of Figure 31C to control temperature. It is preferred but not essential to use inert gasses such as Nitrogen or Argon. Electrical contact is provided by flexible copper clamps 404, 405 which are fixed (e.g. with glue, solder, welding etc.) to the crystal 311 to provide structural support and electrical contact. Copper can be replaced by other good electrical conductors. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 32A uses a soft, elastic material 402 with good thermal and electrical conductivity to surround and support the electro-optic crystal such as a KTN crystal 311. An example of the soft material is a silver loaded gel/silicone/ foam. The electrical contacts 404, 405 to the electro-optic crystal such as a KTN crystal 311 make use of the conductive elastic material 402. An insulating layer 409 is provided to electrically isolate contact 404 from 405. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 32B uses the same materials as in Figure 31C but the forced gas flow 309 to control temperature is replaced with a static gas that cools by convection. It is preferred but not essential to use inert gasses such as Nitrogen or Argon. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

The embodiment of Figure 32C uses the static gas of Figure 32B. It is preferred but not essential to use inert gasses such as Nitrogen or Argon. Electrical and thermal contact to crystal 311 is provided by copper arcuate material 406 which acts as a spring. Surfaces 307, 308 of the electro-optic crystal such as a KTN crystal 311 are preferably exposed so that laser light strikes these surfaces and not the elastic material.

Methods according to the present invention can be performed by a control unit such as a control unit or a processing device 514 shown in Figure 33 or any control unit for use with embodiments of the present invention including microcontrollers, either as a standalone device or embedded in a projector or as part of an optical subsystem for a projector. The present invention can use a processing engine being adapted to carry out functions. The processing engine preferably has processing capability such as provided by one or more microprocessors, FPGA’s, or a central processing unit (CPU) and/or a Graphics Processing Unit (GPU), and which is adapted to carry out the respective functions by being programmed with software, i.e. one or more computer programs. References to software can encompass any type of programs in any language executable directly or indirectly by a processor, either via a compiled or interpretative language. The implementation of any of the methods of the present invention can be performed by logic circuits, electronic hardware, processors or circuitry which can encompass any kind of logic or analog circuitry, integrated to any degree, and not limited to general purpose processors, digital signal processors, ASICs, FPGAs, discrete components or transistor logic gates and similar.

Such a control unit or a processing device may have memory (such as non-transitory computer readable medium, RAM and/or ROM), an operating system, optionally a display such as a fixed format display, ports for data entry devices such as a keyboard, a pointer device such as a “mouse”, serial or parallel ports to communicate other devices, network cards and connections to connect to any of the networks.

The software can be embodied in a computer program product adapted to carry out the functions of any of the methods of the present invention, e.g. as itemised below when the software is loaded onto the controller and executed on one or more processing engines such as microprocessors, ASIC’s, FPGA’s etc. Hence a processing device control unit for use with any of the embodiments of the present invention can incorporate a computer system capable of running one or more computer applications in the form of computer software.

The methods described with respect to embodiments of the present invention above can be performed by one or more computer application programs running on the computer system by being loaded into a memory and run on or in association with an operating system such as WindowsTM supplied by Microsoft Corp, USA, Linux, Android or similar. The computer system can include a main memory, preferably random access memory (RAM), and may also include a non-transitory hard disk drive and/or a removable non-transitory memory, and/or a non-transitory solid state memory. Non-transitory removable memory can be an optical disk such as a compact disc (CD-ROM or DVD-ROM), a magnetic tape, which is read by and written to by a suitable reader. The removable non-transitory memory can be a computer readable medium having stored therein computer software and/or data. The non-volatile storage memory can be used to store persistent information that should not be lost if the computer system is powered down. The application programs may use and store information in the non-volatile memory.

The software embodied in the computer program product is adapted to carry out the following functions when the software is loaded onto the respective device or devices and executed on one or more processing engines such as microprocessors, ASIC’s, FPGA’s etc.:

Driving a first electro-optic crystal exhibiting the Kerr or Pockel effect to steer a laser beam emitted from a first laser light source which passes along an optical path comprising incidence on the first electro-optic crystal exhibiting the Kerr or Pockel effect,

Driving a second electro-optic crystal exhibiting the Kerr or Pockel effect to steer the laser beam which has passed through a half-wave plate and being incident on the second electrooptic crystal exhibiting the Kerr or Pockel effect,

Projecting the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect through at least one optical component towards a projection screen,

Applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect to generate a laser beam spot that is directed to any position on the projection screen to display highlighting for a projected image.

Projecting the image to be projected using separate projector or is processed along a second optical path for displayed,

Driving a spatial light modulator, the beam leaving the electro-optic crystal being incident on spatial light modulator, the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; further comprising driving the spatial light modulator to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

Applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel to keep the average applied voltage equal to zero volts, compensating for a changing DC voltage level, determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly.

Blanking of the beam from the first laser source during compensation, or compensating by placing the first laser source on the aperture, or using multiple crystals so one crystal is “reset” while the other(s) is/are being used.

Controlling the steps load a video frame find highlight location subtract highlight from video frame store coordinate compute masking pattern generate spots, finding highlight locations in the projected image via the steps: dividing the video frame into many small non-overlapping segments and determine for each segment whether or not a highlight is required, if required the highlight is placed centrally in the segment, and subtract the highlight for each required segment and repeat the above steps, or finding highlight locations in the projected image is via the steps: dividing the video frame into many small non-overlapping segments, determine for a segment if a highlight is required, subtract the highlight on its exact spot for this segment, and move to the next segment and repeat above steps, or finding highlight locations in the projected image via the steps: divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment if a highlight has been found, repeat for the same segment if not, move to the next segment and repeat above steps.

Any of the above software may be implemented as a computer program product which has been compiled for a processing engine in any of the servers or nodes of the network. The computer program product may be stored on a non-transitory signal storage medium such as an optical disk (CD-ROM or DVD-ROM), a digital magnetic tape, a magnetic disk, a solid state memory such as a USB flash memory, a ROM, etc.

Claims

1. A method of providing highlighting in a projector system, the method comprising a laser beam emitted from a first laser light source passing along an optical path comprising incidence on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electrooptic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect being directed through at least one optical component towards a projection screen, voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect are controlled to generate a laser beam spot that is directed to any position on the projection screen to display highlighting for a projected image.

2. The method according to claim 1, wherein the projected image is projected by a separate projector or is processed along a second optical path and displayed.

3. The method according to claim 2, wherein the beam leaving the electro-optic crystal is incident on a spatial light modulator.

4. The method according to claim 3, wherein the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the spatial light modulator is driven to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

5. The method according to any previous claims, wherein voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electrooptic crystal exhibiting the Kerr or Pockel are driven to keep the average applied voltage equal to zero volts.

6. The method according to any of the claims 1 to 4, further comprising compensating for a changing DC voltage level.

7. The method according to any of the claims 1 to 4, further comprising determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly

8. The method according to claim 7, further comprising blanking of the beam from the first laser source during compensation, or compensation by placing the first laser source on the aperture, or using multiple crystals so one crystal is “reset” while the other(s) is/are being used.

9. The method according to any of the previous claims, comprising the steps: load a video frame find highlight location subtract highlight from video frame store coordinate compute masking pattern generate spots.

10. The method of claim 9, wherein the step of finding highlight locations in the projected image is via the steps:

11. The method of claim 9, wherein the step of finding highlight locations in the projected image is via the steps:

12. The method of claim 9, wherein the step of finding highlight locations in the projected image is via the steps:

divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment if a highlight has been found, repeat for the same segment if not, move to the next segment and repeat above steps.

13. A system for providing highlighting in a projector system, the system comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, and first and second means for applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electrooptic crystal exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot to any position on the 2D projection screen.

14. The system according to claim 13, further comprising a separate projector for projecting image, or a second optical path along which the projected image is processed and projected and displayed.

15. The system according to claim 13 or 14, wherein the beam leaving the electro-optic crystal is incident on a spatial light modulator.

16. The system according to claim 15, wherein the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the spatial light modulator is driven to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

17. The system according to any of the claims 13 to 16, further comprising a unit to generate voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel and the unit is driven to keep the average applied voltage equal to zero volts.

18. The system according to any of the claims 13 to 16, further comprising means for compensating for a changing DC voltage level.

19. The system according to any of the claims 13 to 16, further comprising means for determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly.

20. The system according to claim 19, further adapted for:

blanking of the beam from the first laser source during compensation, or compensation by placing the first laser source on the aperture, or using multiple crystals so one crystal is “reset” while the other(s) is/are being used.

21. The system according to any of the claims 13 to 20, further comprising: means to load a video frame means to find a highlight location means to subtract a highlight from video frame means to store coordinate means to compute a masking pattern, and means to generate spots.

22. The system of claim 21, wherein means for finding a highlight location in the projected image is adapted to:

23. The system of claim 22, wherein the means to find a highlight location in the projected image is adapted to:

24. The system of claim 22, wherein the means to find a highlight location in the projected image is adapted to:

25. A computer program product which is adapted to execute any of the methods of claims 1 to 12 when executed on a processing engine.

26. A non-transitory signal storage medium storing the computer program product of claim 25.

27. A controller for a projector providing highlighting, the projector comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, the controller comprising first and second means for controlling the application of voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot that is directed to any position on the 2D projection screen.

28. The controller according to claim 27, further for use with a separate projector for projecting image, or a second optical path along which the projected image is processed and projected and displayed.

29. The controller according to claim 27 or 28, wherein the beam leaving the electrooptic crystal is incident on a spatial light modulator.

30. The controller according to claim 29, wherein the spatial light modulator has a plurality of rows and columns of pixels and each pixel has two states, a first state when light is sent towards the projection screen and a second state when light is sent to a light dump; and the controller is adapted to drive the spatial light modulator to send a part of highlights to the light dump when the light projected to the display has a higher intensity than intended.

31. The controller according to any of the claims 27 to 30, further comprising a unit to generate voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel and thecontroller is adapted to drive the unit to keep the average applied voltage equal to zero volts.

32. The controller according to any of the claims 27 to 31, further comprising means for compensating for a changing DC voltage level.

33. The controller according to any of the claims 27 to 31, further comprising means for determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly.

34. The controller according to claim 33, further adapted for:

35. The controller according to any of the claims 27 to 34, further comprising:

36. The controller of claim 35, wherein means for finding a highlight location in the projected image is adapted to:

37. The controller of claim 35, wherein the means to find a highlight location in the projected image is adapted to:

38. The controller of claim 35, wherein the means to find a highlight location in the projected image is adapted to:

39. A raster or vector beam scanner for highlight projectors comprising a first laser light source emitting a laser beam incident on a first electro-optic crystal exhibiting the Kerr or Pockel effect, passing through a half-wave plate and being incident on a second electro-optic crystal exhibiting the Kerr or Pockel effect and the beam emerging from the second electro-optic crystal exhibiting the Kerr or Pockel effect is directed through at least one optical component towards a 2D projection screen, and first and second means for applying voltages to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel effect respectively to steer a laser beam spot to any position on the 2D projection screen.

40. The scanner according to claim 39, further for use with a separate projector for projecting image, or a second optical path along which the projected image is processed and projected and displayed.

41. The scanner according to claim 39 or 40, further comprising a unit to generate voltages applied to the first electro-optic crystal exhibiting the Kerr or Pockel effect and the second electro-optic crystal exhibiting the Kerr or Pockel and thecontroller is adapted to drive the unit to keep the average applied voltage equal to zero volts.

42. The scanner according to any of the claims 39 to 41, further comprising means for compensating for a changing DC voltage level.

43. The scanner according to any of the claims 39 to 41, further comprising means for determining a DC drift by: measuring it with an electronic integrator circuit and ADC converters, or computing it directly when computing highlight locations, or monitor the output spot with an imaging device and adjusting accordingly.

44. The scanner according to claim 43, further adapted for:

45. The scanner according to any of the claims 39 to 44, further comprising: means to load a video frame means to find a highlight location means to subtract a highlight from video frame means to store coordinate means to compute a masking pattern, and means to generate spots.

46. The scanner r of claim 45, wherein means for finding a highlight location in the projected image is adapted to:

47. The scanner of claim 45, wherein the means to find a highlight location in the projected image is adapted to:

48. The scanner of claim 45, wherein the means to find a highlight location in the projected image is adapted to:

divide the video frame into many small non-overlapping segments determine for a segment if a highlight is required subtract the highlight on its exact spot for this segment.