Optics: measuring and testing – By light interference – For dimensional measurement
Reexamination Certificate
1999-05-11
2001-08-14
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By light interference
For dimensional measurement
C356S450000
Reexamination Certificate
active
06275298
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an optical probe assembly, particularly an optical probe assembly for use in determining a physical distance in a camera between two reference surfaces.
BACKGROUND OF THE INVENTION
To capture an image of an object using a camera, an image beam is directed through a lens and onto an image forming medium disposed at an image plane. In conventional photography, photographic film is disposed at the image plane and the image of the object is captured on photographic film. In electronic photography, an imager or image sensor (e.g., a Charge Coupled Device (CCD)), is disposed at the image plane, and the image of the object is captured electronically. For both conventional and electronic photography, it is necessary to properly position the image plane and the lens relative to each other within the camera to provide a focused image.
To properly position the image plane, the position of the image plane needs to be determined. Such a position can be determined relative to a reference surface or reference plane on the camera.
U.S. Pat. Nos. 5,757,485 (Marcus et al) and 5,757,486 (Marcus et al), commonly assigned and incorporated herein by reference, relate to a digital camera image sensor positioning apparatus and method which includes a non-coherent light interferometer. The apparatus and method include an optical probe assembly removably mountable to a digital camera. The non-coherent light interferometer is in communication with the optical probe assembly to determine a depth from a reference surface to the image surface and optical probe assembly. The apparatus and method have been suitable for their intended purpose, however, a need continues to exist for a method for determining (e.g., measuring) a physical distance in a camera between two reference surfaces. Such a method should be robust, comprise simple assembly, be readily constructed and aligned, and usable in a manufacturing environment, particularly by novice users. In particular, for SLR cameras configured for use with 35 mm photographic film or APS format film, a need continues to exist for rapidly measuring a distance between a lens mounting member of the camera and film rails disposed at the image plane. Such a measurement assists in the determination of whether the SLR camera is within manufacturing specifications.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for determining a physical distance in a camera between two reference surfaces.
Another object of the invention is to provide such a robust method which is transportabe, simple to use, and can be readily used with both an electronic camera and a conventional photographic camera.
These objects are given only by way of illustrative example. Thus, other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. The invention is defined by the appended claims.
According to one aspect of the present invention, there is provided a method for measuring a physical distance in a camera between a first reference surface on the camera and a second reference surface on the camera wherein the first reference surface is substantially parallel to the second reference surface. An optical probe assembly is used in the method and includes a housing removably lockable to the camera in a predetermined orientation relative to the first reference surface. The method includes the steps of determining a distance LP from the first reference surface to an optically transparent material disposed intermediate the first and second reference surfaces. An optical probe assembly is removably mounted to the camera, and an optically flat plate is mounted at the second reference surface. Non-coherent light interferometry is used to determine a distance PF between the optically transparent material and the second reference surface. The distances of LP and PF are used to determine a distance between the first reference surface and the second reference surface.
The present invention provides a method for determining a physical distance in a camera between two reference surfaces. The method is robust, transportabe, simple to use, and can be readily used with both a digital camera any a photographic camera.
REFERENCES:
patent: 5757485 (1998-05-01), Marcus et al.
patent: 5757486 (1998-05-01), Marcus et al.
patent: 6075601 (2000-06-01), Marcus et al.
Eastman Kodak Company
Font Frank G.
Natividad Phil
Parulski Susan L.
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