Optical device and optical machining system using the optical device

• US 5,589,955 A
• Filed: 03/18/1993
• Issued: 12/31/1996
• Est. Priority Date: 05/21/1991
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Amako, Jun, Miura, Hirotsuna, Sonehara, Tomio
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): SCHWARTZ, JORDAN MARC
• Application Number:
  US08/033,217
• Time in Patent Office: 1,384 Days
• Field of Search: 359/10, 359/11, 359/21, 359/29, 359/559, 359/560, 359/9, 359/24, 359/35
• US Class Current: 359/9
• CPC Class Codes: B23K 26/066 by using masks
• CPC Class Codes: G02F 1/1313 specially adapted for a particular application
• CPC Class Codes: G03H 1/0005 Adaptation of holography to specific applications holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042
• CPC Class Codes: G03H 1/0808 Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific
• CPC Class Codes: G03H 1/2205 using downstream optical component
• CPC Class Codes: G03H 1/2286 Particular reconstruction light G03H1/24 takes precedence; Beam properties
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 1/32 Systems for obtaining speckle elimination
• CPC Class Codes: G03H 2001/0066 for wavefront matching wherein the hologram is arranged to convert a predetermined wavefront into a comprehensive wave, e.g. associative memory
• CPC Class Codes: G03H 2001/0072 for wavefront conjugation wherein the hologram generates a wavefront conjugating a predetermined object, e.g. null testing, positioning, comparative holography
• CPC Class Codes: G03H 2001/0083 for restoring distorted objects, e.g. restoring objects through scattering media
• CPC Class Codes: G03H 2001/0094 for patterning or machining using the holobject as input light distribution
• CPC Class Codes: G03H 2001/0816 Iterative algorithms
• CPC Class Codes: G03H 2001/0833 Look up table
• CPC Class Codes: G03H 2001/085 Kinoform, i.e. phase only encoding wherein the computed field is processed into a distribution of phase differences
• CPC Class Codes: G03H 2001/221 Element having optical power, e.g. field lens
• CPC Class Codes: G03H 2001/2215 Plane screen
• CPC Class Codes: G03H 2001/2218 being perpendicular to optical axis
• CPC Class Codes: G03H 2001/2221 Screen having complex surface, e.g. a structured object
• CPC Class Codes: G03H 2001/2255 Holobject out of Fourier or hologram planes
• CPC Class Codes: G03H 2001/2297 : using frame sequential, e.g. for reducing speckle noise
• CPC Class Codes: G03H 2001/261 : in optical contact
• CPC Class Codes: G03H 2001/262 : not in optical contact G03H1/30 takes precedence
• CPC Class Codes: G03H 2210/20 : 2D object
• CPC Class Codes: G03H 2210/30 : 3D object
• CPC Class Codes: G03H 2210/33 : 3D/2D, i.e. the object is formed of stratified 2D planes, e.g. tomographic data
• CPC Class Codes: G03H 2210/454 : into planes
• CPC Class Codes: G03H 2210/52 : Alphanumerical
• CPC Class Codes: G03H 2222/16 : Infra Red [IR]
• CPC Class Codes: G03H 2222/31 : Polarised light
• CPC Class Codes: G03H 2222/32 : Unpolarised light
• CPC Class Codes: G03H 2222/35 : Transverse intensity distribution of the light beam
• CPC Class Codes: G03H 2223/13 : Phase mask
• CPC Class Codes: G03H 2223/18 : Prism
• CPC Class Codes: G03H 2225/22 : Electrically addressed SLM [EA-SLM]
• CPC Class Codes: G03H 2225/32 : Phase only
• CPC Class Codes: G03H 2225/33 : Complex modulation
• CPC Class Codes: G03H 2225/34 : Amplitude and phase coupled modulation
• CPC Class Codes: G03H 2225/36 : Polarisation
• CPC Class Codes: G03H 2225/60 : Multiple SLMs

Abstract

The invention provides an optical device with high light utilization efficiency that is capable of scribing patterns on curved surfaces, as well as flat surfaces, using a liquid crystal spatial light modulator. The invention offers an optical device with high light utilization efficiency and that is capable of three-dimensional formation of curved surfaces using a liquid crystal spatial light modulator. Additionally, the invention offers a widely applicable optical processing system that mounts these optical devices on robots. The invention includes at least a coherent light source, a liquid crystal spatial light modulator for controlling the wavefront of the light from the coherent light source, and a means that records the complex amplitude distribution on the liquid crystal spatial light modulator.

Claims

1. An optical device for reproducing an original image pattern on a subject material, the original image pattern being represented by original image pattern data, the optical device, comprising:

a coherent light source that emits a light having a wavefront;

rewritable spatial light modulation means for controlling the wavefront of the light emitted from said light source to produce a plurality of image patterns on the subject material for reproducing the original image; and

electric processing means for generating a plurality of computer hologram data groups and for sequentially supplying the computer hologram data groups to said rewritable spatial light modulation means, said electric processing means including;

means for receiving and storing the original image pattern data,

means for generating a plurality of random phase distribution data groups,

means for multiplying the original image pattern data by each group of the random phase distribution data to produce, respectively, a plurality of data sets, and

means for converting the plurality of data sets produced from said multiplying means to a plurality of computer hologram data groups, respectively, with each computer hologram data group representing one image frame;

wherein the random phase distribution data groups are statistically uncorrelated one another;

wherein said electric processing means supplies the plurality of computer hologram data groups to said rewritable spatial light modulation means on a group-by-group basis, so that the image frames as represented by the computer hologram data groups are supplied to said rewritable spatial light modulation means on a frame-by-frame basis;

wherein said rewritable spatial light modulation means produces and projects an image pattern on the subject material on a pattern-by-pattern basis for each computer hologram data group received from said electric processing means, so that a plurality of image patterns are projected in a series manner and are superposed and integrated at a substantially same location on the subject material to reproduce the original image pattern.

2. The optical device of claim 1 wherein said converting means includes Fourier transformation means for performing Fourier transformation on the plurality of data sets produced from said multiplying means to produce complex amplitude data, means for performing inverse tangent operation on the output of said Fourier transformation means and means for quantizing the output of said means for performing inverse tangent operation to produce the computer hologram data groups.

3. The optical device of claim 1 wherein each of the random phase distribution data groups includes a series of numbers comprising 1 and -1.

4. The optical device of claim 1 wherein electric processing means includes means for counting a number that represents the total number of dots that correspond to areas of the desired pattern to be reproduced, with the number of dots being used for controlling the emission intensity of said coherent light source.

5. The optical device of claim 1 wherein said spatial light modulation means includes liquid crystal spatial light modulation means.

6. The optical device of claim 5 wherein said liquid crystal spatial light modulation means is of a phase modulation type.

7. The optical device of claim 5 wherein said liquid crystal spatial light modulation means comprises two phase modulation type liquid crystal spatial light modulation means which are disposed such that their corresponding pixels oppose each other and their phase modulation orientations are perpendicular to each other.

8. The optical device of claim 1 wherein said electric processing means further includes means for storing a number that represents the total number of dots that correspond to areas of the desired pattern to be reproduced, with the total number of dots being used for controlling the emission intensity of said coherent light source.

9. The optical device of claim 6, further comprising a Fourier transform lens that receives and acts on the wavefront of the light emitted through said phase modulation type liquid crystal spatial light modulation means and reconstructs the original image pattern on the subject material.

10. The optical device of claim 6 wherein said phase modulation type liquid crystal spatial light modulation means is of a type capable of being driven by using an active matrix method and said spatial light modulation means has a same pixel pitch in both horizontal and vertical directions.

11. The optical device of claim 6 wherein said phase modulation type liquid crystal spatial light modulation means is of a type capable of being optically-written.