Optics: measuring and testing – Lens or reflective image former testing
Reexamination Certificate
2000-12-11
2002-12-10
Stafira, Michael (Department: 2877)
Optics: measuring and testing
Lens or reflective image former testing
Reexamination Certificate
active
06493073
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is in the field of optical component measuring and testing and, more particularly, is in the domain of quantitative measurement of lens and mirror power and other optical characteristics.
2. Description of the Prior Art
Optical components for precision applications, such as lenses and mirrors, are now being mass-produced in ever increasing quantities. Many are made by molding monomeric or polymeric materials such as polycarbonates. Some of these materials are cured by heat or exposure to ultra-violet light. Because the molding and curing steps in the manufacturing process cannot be controlled as tightly as required by specifications for new lenses, a need has arisen for a new system and method for measuring properties of optical components at production-line speeds.
One type of precision optical component being manufactured in ever-increasing quantities is the soft contact lens. A high-speed cosmetic defect detection system for contact lenses is taught in European Patent No. EP0882969; however, this system cannot measure power or other optical properties.
Another high-volume precision ophthalmic product is the progressive multifocal ophthalmic spectacle lens of the type described in U.S. Pat. No. 6,102,544. FIG. 1 of that patent is a diagrammatical front view of a progressive multifocal ophthalmic lens comprising three regions of different power. These regions are defined in that patent as a far vision region VL, a near vision region, VP and an intermediate region between the two other regions, VI. The '544 patent defines a reference point for measuring far vision power, L, and a reference point for measuring near vision power, P. The powers measured at reference points L and P define major properties of these lenses.
Progressive spectacle lenses are manufactured at rates of approximately one per second. They are ejected from molding machines in random orientations of the reference points for far vision L and near vision P. This complicates the task of measuring powers at reference points L and P.
Prior art lens meters commonly used at manufacturing sites are manually operated instruments. They can be classified as those that a] measure refraction of one or more beams of light (e.g. U.S. Pat. No. 5,489,978) or b] generate patterns. Of the later, there are some that generate moiré-effect patterns, (e.g. U.S. Pat. No. 5,872,625).
Moiré-effect patterns are generated by superimposing a repetitive design, such as a grid, on the same or a different design in order to produce a pattern distinct from its component designs. Examples are described in Amidror,
The Theory of the Moiré Phenomenon
, Kluwer Academic Publishers, Norwell, Mass. ©2000. Problem 2-27. Testing lenses cites Oster & Nishijima, “Moiré Patterns”,
Scientific American
, May 1963, pp. 54-63, that contains an example of moire-effect rotation when positive and negative optical lenses are placed between a pair of linear-ruled plates.
In order to use a conventional lens meter, an operator first must orient each lens with respect to a lens meter. Then, the operator must make two separate measurements—one for far vision (base) power at reference point L and another for near vision (add) power at reference point P on a lens before the lens is packaged. Each of these two measurements must be accurate to within ⅛ diopter to be commercially useful. However, the accuracy of the measurement can be degraded if an operator selects a measurement point other than L or P. This can readily happen for lenses with low add powers at reference points P or if the inspector has a visual acuity deficiency. Manual inspection is not economical for such high-speed inspection because it is too slow, because human inspectors are prone to making biased judgments and because inspection results among different inspectors are not uniform.
One principal obstacle to automatic inspection of optical components has been the difficulty of generating rapidly a comprehensive map of component optical properties, such as power at each point on the component's optical surface.
Another principal obstacle to automatic inspection of optical components has been the requirement that the component be oriented in a preferred position before measurements can be obtained with instruments—such as lensometers—of the prior art.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a robust in situ system and method for measuring properties, such as power, of optical components, such as lenses and mirrors.
A second object of this invention is to provide a system and method for measuring properties of an optical component without requiring that the component be rotationally oriented in a preferred position about its optical axis before measurements can be obtained.
A third object of this invention is to provide a system and method for generating rapidly a comprehensive moiré-effect map of component optical properties, such as power at each point on the component's optical surface.
A fourth object of this invention is to provide an accurate system and method for analyzing maps of component optical properties so as to be able to measure power and other variables for the entire component.
REFERENCES:
patent: 4303341 (1981-12-01), Kleinknecht et al.
patent: 4408884 (1983-10-01), Kleinknecht et al.
patent: 5119434 (1992-06-01), Bishop et al.
patent: 5243542 (1993-09-01), Noguchi
patent: 5307141 (1994-04-01), Fujieda
patent: 5406375 (1995-04-01), Brandstetter
patent: 5440383 (1995-08-01), Bacchus
patent: 5581347 (1996-12-01), Le Saux et al.
patent: 5613013 (1997-03-01), Schuette
patent: 5872625 (1999-02-01), Kajino et al.
patent: 5973773 (1999-10-01), Kobayashi
patent: 6102544 (2000-08-01), Baudart et al.
Oster & Nishijima, Moire Patterns, Scientific American, May 1963, pp. 54-63.
Kafri et al, The Physics of Moire Metrology, 1990, pp. 36-37, 58-136, 174-194 John Wiley & Sons, New York, NY, USA.
AMIDROR, The Theory of the Moiré Phenomenon, Kluwer Academic Publishers, Norwell MA, pp. 57-58 (Problem 2-27—Testing lenses) & pp 249-352; ©2000.
Epstein Sheldon L.
Stafira Michael
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