System for making a hologram of an image

Abstract

A system for converting an image into a hologram formed from diffraction gratings includes obtaining image data for each pixel in an image to be converted, putting the image into digital form and using the image data to control portions of a laser beam split into a reference beam and at least one object beam. The diffraction gratings are formed by an interference pattern of a reference beam and at least one object beam. intersecting on a profitable surface on a pixel-by-pixel basis. Modulation of at least one object beam and adjustment of the angle at which that beam interferes with the reference beam on the profitable surface is used to reflect image data for each pixel of the image being converted into a hologram. By using this method and selecting the spacings between pixel pairs on the profitable surface, the angle at which a viewer will see a predetermined image or reflecting light from the hologram is determined, as well as the apparent position of image created by reflecting light from the hologram comprising the spaced diffraction gratings.

What is claimed is:  
     
         1 . A method of converting an image into a hologram, the method comprising: 
 receiving a set of data regarding a copied image;    assigning the set of data to a selected pixel of a set of pixels which are located within a coordinate system and representative of the image;    splitting a laser beam into a reference beam and at least one object beam;    directing the reference beam and the at least one object beam along separate paths so as to interfere at a prescribed location on a profileable surface;    wherein each object beam of the at least on object beam subtends a different angle with respect to the profileable surface;    wherein the prescribed location on the profileable surface coincides with the selected pixel; and    in accordance with the set of data assigned to the selected pixel, controlling the interference of the reference beam and the at least one object beam.    
     
     
         2 . The method as set forth in  claim 1  further comprising digitally encoding the received data.  
     
     
         3 . The method as set forth in  claim 1  wherein controlling the interference of the reference beam and the at least one object beam includes at least one of selecting an object beam, directing the orientation of an object beam with respect to the profileable surface and causing an object beam and the reference beam to interfere for a prescribed duration in time.  
     
     
         4 . The method as set forth in  claim 3  wherein directing the orientation of the an object beam with respect to the profileable surface includes rotating the object beam with respect to the reference beam.  
     
     
         5 . The method as set forth in  claim 3  wherein causing an object beam and the reference beam to interfere for a prescribed duration in time includes intermittently blocking passage of the object beam.  
     
     
         6 . The method as set forth in  claim 1  wherein the set of data comprises at least one of the pixel location within the coordinate system, the duration in time for which the object beam and the reference beam interfere, the size of the selected pixel, and the orientation of the object beam with respect to the profileable surface.  
     
     
         7 . The method as set forth in  claim 1  wherein the profitable surface comprises a photosensitive surface.  
     
     
         8 . The method as set forth in  claim 1  further comprising: 
 for successive selected pixels within the coordinate system receiving a successive set of data regarding the image;  
 assigning the successive set of data to the successive selected pixel within the coordinate system;  
 causing relative movement between the profileable surface and the reference and object beams;  
 directing the reference beam and the at least one object beam along separate paths so as to interfere at a successive prescribed location on the profileable surface;  
 wherein the successive prescribed location on the profileable surface coincides with the successive selected pixel; and in accordance with the successive set of data assigned to the successive selected pixel, controlling the interference of the reference beam and the at least one object beam.  
 
     
     
         9 . The method as set forth in  claim 1  wherein receiving a set of data regarding the image includes scanning the image into a device which provides digital output representative of the image.  
     
     
         10 . The method as set forth in  claim 1  wherein receiving a set of data regarding the image includes receiving computer-generated data for each of the pixels representing the image.  
     
     
         11 . The method as set forth in  claim 10  wherein a plurality of images are computer-generated, and a plurality of patterns are recorded on the profileable surface corresponding to the plurality of computer-generated images.  
     
     
         12 . The method as set forth in  claim 1  wherein directing the reference beam and the at least one object beam includes: 
 diffusing the laser beam; and  
 refocusing the laser beam.  
 
     
     
         13 . The method as set forth in  claim 1 , further comprising storing the received set of data in memory.  
     
     
         14 . The method as set forth in  claim 13  wherein the data is stored for a prescribed time period while directing the reference beam and the at least one object beam.  
     
     
         15 . The method as set forth in  claim 1  further comprising determining the size of at least one pixel.  
     
     
         16 . The method as set forth in  claim 15  wherein the size of the pixel is adjusted by a prescribed factor.  
     
     
         17 . The method as set forth in  claim 1 , wherein the at least one object beam includes three object beams, each representing primary color data for the selected pixel.  
     
     
         18 . The method as set forth in  claim 17  wherein each of the object beams is coincident with the reference beam at the prescribed location on the profileable surface at different times in a prescribed sequence.  
     
     
         19 . The method as set forth in  claim 1  wherein a plurality of object beams are simultaneously coincident at the prescribed location with the reference beam on the profileable surface in a prescribed sequence.  
     
     
         20 . The method as set forth in  claim 1 , wherein the object beam is modulated based upon at least one of brightness data, color scale data and gray scale data for the selected pixel.  
     
     
         21 . The method as set forth in  claim 7 , wherein the reference beam is modulated based upon a scale between black and white for the selected pixel.  
     
     
         22 . The method as set forth in  claim 21 , further comprising developing the photosensitive surface to form a hologram.  
     
     
         23 . The method as set forth in  claim 2 , further comprising storing the encoded data in a memory.  
     
     
         24 . The method as set forth in  claim 1  wherein each of the paths is of equal length.  
     
     
         25 . The method as set forth in  claim 20  wherein modulating the object beam includes interfering more than one object beam simultaneously with the reference beam.  
     
     
         26 . The method as set forth in  claim 9  wherein the set of data is computer-generated using mathematical algorithms.  
     
     
         27 . The method as set forth in  claim 9  wherein the set of data is obtained by computer manipulation of the scanned images.  
     
     
         28 . The method as set forth in  claim 10  wherein the set of data is computer-generated using a drawing program operated on a computer.  
     
     
         29 . The method as set forth in  claim 9  wherein the set of data is obtained by means of a video camera.  
     
     
         30 . The method as set forth in  claim 9  further comprising recovering the image by scanning the hologram with a coherent beam of light.  
     
     
         31 . The method as set forth in  claim 9  further comprising recovering the image by scanning the hologram using a point source of light.  
     
     
         32 . The method as set forth in  claim 1  wherein directing the at least one object beam includes reflecting the at least one object beam.  
     
     
         33 . The method as set forth in  claim 20  wherein modulating the object beam comprises alternately blocking and passing the object beam.  
     
     
         34 . The method as set forth in  claim 4  wherein rotating the object beam comprises rotating an optical apparatus to vary the angles of incidence of the at least one object beam with respect to the profileable surface.  
     
     
         35 . The method as set forth in  claim 8  wherein causing relative movement between the profileable surface and the reference and object beams comprises moving the profileable surface or the reference and object beams in a rectilinear coordinate system.  
     
     
         36 . The method as set forth in  claim 34  wherein each position of the optical apparatus results in a different set of angles of incidence with respect to the profileable surface for each object beam, each set of angles corresponding to a different viewing angle for the resulting hologram.  
     
     
         37 . The method as set forth in  claim 8  wherein causing relative movement between the profileable surface and the reference and object beams comprises moving the profileable surface or the reference and object beams in a cylindrical coordinate system.  
     
     
         38 . The method as set forth in  claim 8  wherein directing the reference beam and the at least one object beam comprises: 
 diffusing the reference beam;  
 refocusing the reference beam.  
 
     
     
         39 . The method as set forth in  claim 34 , wherein the optical apparatus is rotationally repositioned a plurality of times for each pixel.  
     
     
         40 . The method as set forth in  claim 1  wherein directing the reference beam and the object beam comprises passing the reference beam and the object beam through a limiting aperture.  
     
     
         41 . The method as set forth in  claim 40  wherein at least one of the reference beam and the object beam is given a predetermined shape by the limiting aperture.  
     
     
         42 . The method as set forth in  claim 41  wherein at least one of the reference beam and the object beam having a predetermined shape is passed through a neutral density filter.  
     
     
         43 . The method as set forth in  claim 1  wherein directing the reference beam and the object beam comprises modulating at least one of the reference beam and the object beam in and out of phase with respect to one another.  
     
     
         44 . The method as set forth in  claim 1  wherein directing the reference beam and the object beam comprises spatially filtering at least one of the reference beam and the object beam.  
     
     
         45 . The method as set forth in  claim 1  wherein the method is carried out with a plurality of devices, each configured to carry out the entire method independently, where the plurality of devices carry out the method simultaneously on a single profileable surface.  
     
     
         46 . The method as set forth in  claim 1  further comprising hardening the photosensitive material.  
     
     
         47 . The method as set forth in  claim 46  further comprising applying the hardened photosensitive material to a receptive plastic material thereby embossing the receptive plastic material.  
     
     
         48 . A method of converting an image into a hologram, the method comprising: 
 obtaining pixel data for a copied image;    splitting a laser beam having a coherence length suitable for forming holograms into a reference beam and at least one of object beam;    directing the reference beam and the at least one object beam along different pathways, the difference in the pathways having a length less than the coherence length of the laser beam; and    modulating the at least one object beam in accordance with the pixel data wherein the at least one object beam is coincident with the reference beam on a profileable surface at different angles with respect to the profileable surface for each pixel forming thereby the pattern of diffraction gratings.    
     
     
         49 . The method as set forth in  claim 48  wherein the profitable surface comprises a photosensitive surface.  
     
     
         50 . The method as set forth in  claim 49  further comprising serially causing relative motion between the profileable surface and the reference beam and at least one object beam so as to direct the reference beam and the at least one object beam to successive pixel locations on the profileable surface.  
     
     
         51 . The method as set forth in  claim 50  further comprising repeating splitting a laser beam, directing the reference beam and the at least one object beam along different pathways, modulating the at least one object beam in accordance with the pixel data and serially causing relative motion between the profileable surface and the reference beam and at least one object beam for each successive pixel location so that a pixel pattern is formed on the profileable surface corresponding to the image.  
     
     
         52 . The method as set forth in  claim 49  wherein the at least one object beam is coincident with the reference beam at the profileable surface in a prescribed sequence.  
     
     
         53 . The method as set forth in  claim 52  wherein one object beam is coincident with the reference beam at the profileable surface at one time.  
     
     
         54 . The method as set forth in  claim 52  wherein a plurality of the object beams are coincident with the reference beam at the profileable surface simultaneously.  
     
     
         55 . The method as set forth in  claim 51  wherein the angles of the at least one object beam are adjusted to correspond to an optimum viewing angle for the hologram.  
     
     
         56 . The method as set forth in  claim 55  wherein the method is carried out more than once for selected pixels of the image.  
     
     
         57 . The method as set forth in  claim 49  wherein obtaining pixel data is carried out by scanning an image into a device which provides digital output representative of the image.  
     
     
         58 . The method as set forth in  claim 49  wherein obtaining pixel data is carried out by computer-generating data regarding the image.  
     
     
         59 . The method as set forth in  claim 55  wherein the laser beam is adjusted by an optical system, and the optical system is rotated to adjust the angles of the at least one object beam.  
     
     
         60 . The method as set forth in  claim 49  wherein the spacing between adjacent pixels is adjusted to determine the extent of image depth perception for the hologram when viewed from an optimum angle.  
     
     
         61 . The method as set forth in  claim 60  wherein the process is repeated a plurality of times at selected pixel locations using different angles for each object beam for each operation of the method, wherein the image of the hologram appears altered depending upon the angle from which the hologram is viewed.  
     
     
         62 . An apparatus for converting an image into a hologram, the apparatus comprising: 
 means for processing a set of data regarding a copied image, the set of data assigned to a selected pixel of a set of pixels which are located in a coordinate system and representative of the image;    a radiation source configured to generate a laser beam having a coherence length suitable for forming a hologram;    an optical system arranged to split and direct the laser beam into a reference beam and at least one object beam along separate pathways so as to interfere at a prescribed location on a profitable surface coincident with the selected pixel, the path difference having a length within the coherence length of the laser beam; and    a controller controlling, in accordance with the set of data assigned to the selected pixel, the interference of the reference beam and the at least one object beam.    
     
     
         63 . The apparatus as set forth in  claim 60  wherein the controller controls at least one of the duration in time of the interference of the reference beam and the object beam, the angle of incidence of the at least one object beam with respect to the profitable surface, the location, on the profitable surface, of the interference of the reference beam and the object beam, the area of the interference of the object beam and the reference beam and the relative movement of the laser beam and the profitable surface.  
     
     
         64 . The apparatus as set forth in  claim 60  wherein means for processing a set of data comprises a computer receptive of the set of data regarding a scanned image.  
     
     
         65 . The apparatus as set forth in  claim 60  wherein means for processing a set of data comprises a computer having a computer program for generating an image based upon mathematical algorithms.  
     
     
         66 . The apparatus as set forth in  claim 60  wherein means for processing a set of data comprises a computer having a program permitting a user to manually construct an image.  
     
     
         67 . The apparatus as set forth in  claim 60  wherein the optical system comprises: 
 a light diffuser; and  
 a lens for refocusing diffused light.  
 
     
     
         68 . The apparatus as set forth in  claim 60  wherein the optical system is mounted on a roller bearing moved by a stepping motor controlled by the controller.  
     
     
         69 . The apparatus as set forth in  claim 65  wherein the light diffuser comprises a ground glass screen.  
     
     
         70 . The apparatus as set forth in  claim 60  wherein the optical system further comprises a set of shutters to alternately block and pass the reference beam and the at least one object beam.  
     
     
         71 . The apparatus as set forth in  claim 60  further comprising means for causing relative movement between the profitable surface and the laser beam.  
     
     
         72 . The apparatus as set forth in  claim 68  wherein means for causing relative movement between the profitable surface and the laser beam comprises a stage movable along a prescribed coordinate system.  
     
     
         73 . The apparatus as set forth in  claim 60  further comprising: 
 a second laser source; and  
 a second optical system arranged so that multiple exposures of interfering reference and object beams can be carried out simultaneously at more than one position on the same photosensitive surface.  
 
     
     
         74 . An apparatus for converting image into a hologram formed from diffraction gratings based upon pixels representative of the image, the apparatus comprising: 
 a laser source configured to generate a laser beam with a coherence length suitable for forming a hologram;    a focusing lens assembly;    a main shutter arranged to control the laser beam;    optical means for splitting the laser beam into a reference beam and at least one of object beam thereby directing the reference beam and the at least one object beam along different pathways so that each object beam is coincident upon a profileable surface with the reference beam at different angles, and for modulating the object beams so that each object beam is coincident upon the profileable surface with the reference beam in a predetermined sequence;    an isolation bench to support the apparatus;    a support mounted on the isolation bench and arranged to support the focusing lens assembly and the optical means;    a first stepper motor for moving the profileable surface in a prescribed coordinate system;    a second stepper motor for rotating the optical means;    data processing means for providing data for each pixel constituting the image;    means for correlating the pixel data to the operation of the main shutter, the optical means and the first and second stepper motors; and    means for monitoring the hologram as it is generated.    
     
     
         75 . The apparatus as set forth in  claim 72  further comprising interface means between the data processing means and each of the main shutter, the focusing lens assembly and the first and second stepping motors.  
     
     
         76 . The apparatus as set forth in  claim 72  wherein monitoring means comprises a video camera and a video monitor.  
     
     
         77 . The apparatus as set forth in  claim 72  wherein data input means comprises a keyboard, and wherein central processing means includes a program for generating images.  
     
     
         78 . The apparatus as set forth in  claim 72  wherein data input means comprises a video camera.  
     
     
         79 . The apparatus as set forth in  claim 60  wherein a plurality of object beams interfere with the reference beam on the photosensitive surface in a predetermined sequence to form diffraction gratings.  
     
     
         80 . A method of converting an image into a hologram formed from diffraction gratings, the method comprising: 
 obtaining pixel data from a copied image;    splitting a laser beam having a coherence length suitable for forming holograms into a reference beam and at least one object beam;    directing the reference beam along different pathways, each pathway having a length within the coherence length;    altering the pathway of the at least one object beam so that the at least one object beam is coincident on a profileable surface at a plurality of different angles, wherein the object beam interferes with the reference beam on the profileable surface to form diffraction gratings for each pixel.    
     
     
         81 . The method as set forth in  claim 78  wherein each selected pixel is exposed to a plurality of interferences between the reference beam and the at least one object beam.  
     
     
         82 . The method as set forth in  claim 78  wherein the reference beam is coincidence with the profileable surface at a 90 degree angle.  
     
     
         83 . An apparatus for converting image data into a hologram formed on a profileable surface from diffraction gratings based upon pixels representative of the image, the apparatus comprising; 
 means for processing image data for each pixel representing a copied image;    a laser source configured to generate a beam with a coherence length suitable for forming a hologram;    an optical system arranged to split and direct the laser beam into a reference beam and at least one object beam along pathways having a length within the range of the coherence length;    means for causing relative movement between the profileable surface and the laser beam; and    a controller comprising means for controlling the radiation of the profileable surface on a pixel-by-pixel basis.    
     
     
         84 . The apparatus as set forth in  claim 81  wherein the optical system comprises a rotating head arranged to change the angle of incidence of the object beam according to rotational positioning of the rotating head.  
     
     
         85 . The apparatus as set forth in  claim 81  wherein means for controlling irradiation comprises: 
 means for generating control signals to control modulation of the reference and object beams in accordance with image data for each the pixel;  
 means for generating controls signals to change angles of incidence of the reference beam and the object beams on the profileable surface so that each the angle of incidence corresponds to image data for a selected pixel; and  
 means for generating control signals to control means for moving the photosensitive surface in accordance with pixel location as defined in a prescribed coordinate system.  
 
     
     
         86 . A method of converting an image into a hologram formed from diffraction gratings, the method comprising: 
 obtaining pixel data of a copied image;    manipulating a laser beam according to pixel data characteristics;    irradiating a profileable surface with the manipulated laser beam to form interference patterns on a pixel-by-pixel basis, the interference patterns of each pixel being characteristic of image data or corresponding pixels of the image.    
     
     
         87 . The method as set forth in  claim 84 , further comprising adjusting distances between adjacent pixels to control apparent location of an image generated by reflecting light from the hologram.  
     
     
         88 . The apparatus as set forth in  claim 81  wherein the optical system comprises: 
 a beam splitter;  
 a mirror arranged at a prescribed angle to the reference beam; and  
 means for moving the mirror with respect to the beam splitter.  
 
     
     
         89 . The apparatus as set forth in  claim 86  wherein the optical system further comprises: 
 a second mirror arranged at a 45 degree angle to the reference beam, wherein the second mirror is split into a first portion and a second portion, the first portion being fixed and the second portion being movable; and  
 means for moving the second portion to variably redirect light reflected from the first mirror.  
 
     
     
         90 . The apparatus as set forth in  claim 81  further comprising means for determining the deviation in an actual laser beam path from a desired laser beam path.  
     
     
         91 . The apparatus as set forth in  claim 88 , wherein the means for detecting comprises: 
 a second laser source;    a mirror having an opening;    a focusing lens; and    a sensor connected to the controller.    
     
     
         92 . A storage medium encoded with machine-readable computer program code for converting an image into a hologram, the program code including instructions for causing the computer system to implement a method comprising: 
 receiving a set of data regarding a copied image;    assigning the set of data to a selected pixel of a set of pixels which are located within a coordinate system and representative of the image;    splitting a laser beam into a reference beam and at least one object beam;    directing the reference beam and the at least one object beam along separate paths so as to interfere at a prescribed location on a profileable surface;    wherein each object beam of the at least on object beam subtends a different angle with respect to the profileable surface;    wherein the prescribed location on the profileable surface coincides with the selected pixel; and    in accordance with the set of data assigned to the selected pixel, controlling the interference of the reference beam and the at least one object beam.    
     
     
         93 . A method of converting an image into a hologram formed from diffraction gratings the method compromising: 
 obtaining data regarding the image according to a coordinate system to derive position data and corresponding image data for each pixel of a plurality of pixels representing the image;    directing a beam from a laser having a predetermined coherence length onto a photosensitive surface in a sequence corresponding to pixel position data representing the image so as to react with the photosensitive surface forming diffraction gratings, the step of directing including: 
 splitting the laser beam into a plurality of beam parts;  
   directing a first beam part of the laser beam as a reference beam to the photosensitive surface along a first pathway;    directing others of the plurality of beam parts along a plurality of other pathways, each of the other pathways being a length within a range defined by the coherence length of the laser;    modulating the plurality of beam parts in accordance with the data for a selected pixel so that the others of the plurality of beam parts are modulated separately from the first beam part, modulation of the others of the beam parts being based on image data for the selected pixel, wherein the others of the beam parts are coincidence with the first beam part on the photosensitive surface at different angles with respect to the photosensitive surface for a selected pixel; and    serially moving the photosensitive surface with respect to the laser beam so as to redirect the laser beam to a pixel location successive to the selected pixel location on the photosensitive surface in correspondence to the coordinate system.    
     
     
         94 . A method of converting an image into a hologram, the method comprising: 
 receiving a set of data regarding a copied image;    assigning the set of data to a selected pixel of a set of pixels which are located within a coordinate system and representative of the image;    splitting a laser beam into a reference beam and at least one object beam;    directing the reference beam and the at least one object beam along separate paths so as to interfere at a prescribed location on a surface;    wherein each object beam of the at least on object beam subtends a different angle with respect to the surface;    wherein the prescribed location on the surface coincides with the selected pixel; and    in accordance with the set of data assigned to the selected pixel, controlling the interference of the reference beam and the at least one object beam.