US4833314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable phase stop for use in interferometers
Assignee: The AT&T MVPD Group LLC
•
Filing: 1988-08-22
•
Granted: 1989-05-23
•
Expires: 2008-08-22
Abstract
Abstract An electro-optical device (10) is used to alter characteristics of a light beam passing through it. In a particularly preferred embodiment, the device (10) is used as a phase stop having a dynamically variable aperture whose size is defined by the selected application of an electrical potential across one or more concentric, transparent ring-like electrodes (13, 14, 16 and 18). The electro-optical device (10) finds particular utility in a common-path interferometer (40) where fringe visibility is optimized by using suitable servo-electronics (56) to select an appropriate aperture size for the phase stop (10).
Inventors
- 👤 David M. Pepper
- 👤 Thomas R. O'Meara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:48
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1343; G02F1/134309; G01; G01J; G01J9/00; G01J9/02; G02F1/1313
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
204 words
A common-path interferometer comprising: an input beam for illuminating an object to be analyzed; a first lens for focusing the input beam to a given plane; a substantially transparent electro-optical variable phase stop device having a cell body at said given plane, said electro-optical device having a first electrode on one surface of the cell, with an opposite surface of the cell having at least one second electrode mounted thereon, said cell being made of electro-optical material for transmitting substantially all of the light from the beam while selectively creating a maximum phase shift of about 90 degrees to portions of the beam passing through it; a second lens for collimating light passing through the electro-optical device; a detector array at said output plane for detecting interference patterns therein and providing an output associated with fringe visibility of the interference pattern; and servo means connected between the detector array and the electro-optical device, said servo means being adapted to apply an electric voltage to the electrodes to optimize fringe visibility by dynamically altering the amount of light which is phase shifted with respect to that portion of the light in the input beam passing through the electro-optical device which is not shifted in phase.
Claim 2
Dependent Claim
204 words
A common-path interferometer comprising: an input beam for illuminating an object to be analyzed; a first lens for focusing the input beam to a given plane; a substantially transparent electro-optical variable phase stop device having a cell body at said given plane, said electro-optical device having a first electrode on one surface of the cell, with an opposite surface of the cell having at least one second electrode mounted thereon, said cell being made of electro-optical material for transmitting substantially all of the light from the beam while selectively creating a maximum phase shift of about 90 degrees to portions of the beam passing through it; a second lens for collimating light passing through the electro-optical device; a detector array at said output plane for detecting interference patterns therein and providing an output associated with fringe visibility of the interference pattern; and servo means connected between the detector array and the electro-optical device, said servo means being adapted to apply an electric voltage to the electrodes to optimize fringe visibility by dynamically altering the amount of light which is phase shifted with respect to that portion of the light in the input beam passing through the electro-optical device which is not shifted in phase.
Claim 3
Dependent Claim
12 words
The interferometer of claim 1 wherein the input beam is white light.
Claim 4
Dependent Claim
15 words
The interferometer of claim 1 wherein the electro-optical cell is made of liquid crystal material.
Claim 5
Dependent Claim
39 words
The interferometer of claim 1 wherein said first and second electrodes each comprise single electrical contacts to the cell; and wherein a variable voltage source is connected between the electrodes to generate fringing electrical fields in the electro-optical material.
Claim 6
Dependent Claim
25 words
The interferometer of claim 4 wherein said first and second electrodes comprise disc-shaped electrodes concentrically located in the middle of the surfaces of the cell.
Claim 7
Dependent Claim
37 words
The interferometer of claim 4 wherein said second electrode has an electrical resistance which varies radially outwardly from the middle of said opposite surface of the cell to thereby affect electric field distribution throughout the electro-optical material.
Claim 8
Dependent Claim
49 words
The interferometer of claim 4 wherein said first electrode substantially covers said one surface of the cell; and wherein said second electrode covers the opposite surface except for an opening centrally located therein; and wherein said servo means applies a variable voltage source between the first and second electrodes.
Claim 9
Dependent Claim
37 words
The interferometer of claim 1 wherein said first electrode comprises a generally continuous electrode covering said one surface; and wherein said at least one second electrode comprises a plurality of concentric ring electrodes on said opposite surface.
Claim 10
Dependent Claim
68 words
The interferometer of claim 8 wherein a plurality of fixed voltage sources are connected to each ring electrode; and wherein said servo means applies said voltage sources to selected ring electrodes as a function of the output of the detector array to thereby alter the size of the diameter of the beam that is phase shifted with respect to outer portions of the beam passing through the cell.
Claim 11
Independent Claim
159 words
A method of analyzing objects of different spatial frequency content, said method comprising: illuminating the object with a beam of white light; passing the beam through a substantially transparent variable phase stop device, said device having a cell body made of electro-optical material for transmitting substantially all of the light from the beam while selectively creating a maximum phase shift of about 90 degrees to portions of the beam passing through it; applying first and second electrodes to opposite surfaces of the cell; illuminating a detector array with the beam passing through the phase stop device; optimizing the fringe visibility of an interference pattern at the detector array by applying an electrical voltage to the electrodes to cause the electro-optical material in a selected portion of the cell to change characteristics and shift the phase of the light beam striking the changed material substantially 90 degrees with respect to the remaining portion of the beam passing through the device.
Claim 12
Independent Claim
159 words
A method of analyzing objects of different spatial frequency content, said method comprising: illuminating the object with a beam of white light; passing the beam through a substantially transparent variable phase stop device, said device having a cell body made of electro-optical material for transmitting substantially all of the light from the beam while selectively creating a maximum phase shift of about 90 degrees to portions of the beam passing through it; applying first and second electrodes to opposite surfaces of the cell; illuminating a detector array with the beam passing through the phase stop device; optimizing the fringe visibility of an interference pattern at the detector array by applying an electrical voltage to the electrodes to cause the electro-optical material in a selected portion of the cell to change characteristics and shift the phase of the light beam striking the changed material substantially 90 degrees with respect to the remaining portion of the beam passing through the device.
Claim 13
Dependent Claim
51 words
The method of claim 10 which further comprises: generating an output signal associated with fringe visibility of the interference pattern at the detector array; and using said output signal to generate a feedback signal for dynamically altering the applied electrical voltage so as to optimize fringe visibility at the detector array.
Claim 14
Dependent Claim
127 words
A variable phase stop device for shifting a portion of a light beam substantially 90 degrees with respect to remaining portions of the beam passing through the device, said device comprising: an electro-optical cell having two major surfaces; a first electrode on one surface; a second electrode on an opposite surface; said cell being made of electro-optical material for transmitting substantially all of the light from the beam passing therethrough while selectively creating a maximum phase shift of about 90 degrees with respect to portions of the remaining beam passing through it; and a variable voltage source connected between the first and second electrodes for creating fringing electrical fields therebetween for altering characteristics of the electro-optical material to cause the phase shift of light passing through it.
Claim 15
Dependent Claim
127 words
A variable phase stop device for shifting a portion of a light beam substantially 90 degrees with respect to remaining portions of the beam passing through the device, said device comprising: an electro-optical cell having two major surfaces; a first electrode on one surface; a second electrode on an opposite surface; said cell being made of electro-optical material for transmitting substantially all of the light from the beam passing therethrough while selectively creating a maximum phase shift of about 90 degrees with respect to portions of the remaining beam passing through it; and a variable voltage source connected between the first and second electrodes for creating fringing electrical fields therebetween for altering characteristics of the electro-optical material to cause the phase shift of light passing through it.
Claim 16
Dependent Claim
34 words
The device of claim 12 wherein said first electrode substantially covers one surface of the electro-optical cell; and wherein the second electrode substantially covers the opposite surface except for an opening centrally located therein.
Claim 17
Dependent Claim
27 words
The device of claim 12 wherein said first and second electrodes each comprise disc-shaped electrodes concentrically located in the middle of the major surfaces of the cell.
Claim 18
Dependent Claim
26 words
The device of claim 12 wherein said first electrode has an electrical resistance which radially varies outwardly from the middle of one surface of the cell.
References Cited (Backward Citations)
US2766655A
Cited
US3402001A
Cited
US3634695A
Cited
US3646608A
Cited
US4313663A
Cited
US4333720A
Cited
US4309602A
Cited
JPS56114923A
Cited
US4370024A
Cited
JPS58184115A
Cited
JPS59105613A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-22 | 1992-11-21 | 1993-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-22 | 1996-11-21 | 1997-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-22 | 2000-11-21 | 2001-05-23 | $7700.00 | Window Closed / Lapsed |