Optics: measuring and testing – Lens or reflective image former testing – For optical transfer function
Patent
1993-11-30
1995-08-08
Rosenberger, Richard A.
Optics: measuring and testing
Lens or reflective image former testing
For optical transfer function
G01B 900
Patent
active
054403839
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an optical device of the deflectometer-type, particularly for phase detection, with wide range of measurement.
BACKGROUND OF THE INVENTION
The high technologies employed nowadays in numerous optical and mechanical systems, often require surfaces produced with submicronic precision. In addition to mastering the machining processes, there is the problem of quality control of the obtained components.
U.S. Pat. No. 5,066,119 describes an optical device, adapted for the control, by phase detection, of any surface of an optical system, comprising essentially, along an optical path: emission means adapted to constitute a light source, a reflecting surface to be tested, a separator cube disposed between the light source and the surface to be tested and provided with a semi-reflecting surface to divert the light beam reflected by the surface to be tested, a grating such as a Ronchi grating, disposed adjacent the point of convergence of said reflected light beam, an objective to give the image observable in the analysis plane of a camera with a charge coupled device (CCD), which is to say in the plane of the CCD detector, and a camera coupled to data processing means for use of the image by phase detection.
This optical device, of the deflectometer type, with phase detection, permits precise and rapid measurement, for any surface, and without contact, of a large variety of optical and aspherical surfaces, without specific tools. It has however, by virtue of its principle, limits in terms of the diameter of the measurable range, particularly because of the entrance pupil of its acquisition system.
SUMMARY OF THE INVENTION
An object of the invention is to increase the entry pupil of an imaging system, particularly a deflectometer, so as to increase its measurable field.
Another object of the invention is to use a zoom for observation of the image given by a deflectometer.
The invention has for its object an optical device, of the deflectometer type, particularly for phase detection, comprising a luminous source, a surface to be tested, a semi-reflective surface between the light source and the surface to be tested to deflect the light beam reflected by the surface to be tested, a grating placed adjacent the point of convergence of said reflected light beam, and a CCD camera coupled to data processing means, characterized in that it comprises, between the grating and the CCD camera, a primary objective with a large entry pupil supplying an intermediate image, a ground glass adapted to receive said intermediate image, and a secondary optical system through which the intermediate image on the ground glass passes and which forms a final image on the detector of the CCD camera.
According to another characteristic of the invention, the secondary optical system is a zoom.
BRIEF DESCRIPTION OF THE DRAWINGS
Other characteristics will appear from the description which follows with reference to the accompanying drawings, in which can be seen:
FIG. 1: a schematic view of an optical device of known type, with a grating and separator element, for the testing, by phase detection, of an optical surface;
FIG. 2: a schematic view of the rays emitted by the light source and reflected by an aspherical optical surface;
FIG. 3: schematic view illustrating the defocalization relative to the schematic view of FIG. 2;
FIG. 4: a schematic view of the principle of the optical device of FIG. 1;
FIG. 5: a schematic view of the principle of the optical device according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1 can be seen light source 1, a semi-reflective surface 2, the optical surface 3 to be tested, a Ronchi grating 4, an objective 5, a detector 6 of a CCD camera (not shown), and data processing means 7.
The optical surface 3 being aspherical, a beam 8 from the source 1 reaches surface 3 at point 9, and is reflected at 10. The beam 10 is deflected at 11 by a semi-reflective surface 2, and it reaches the grating 4 at a point 12 spaced a distance d from point 13 s
REFERENCES:
patent: 5066119 (1991-11-01), Bertrand
patent: 5066120 (1991-11-01), Bertrand
patent: 5187539 (1993-02-01), Adachi et al.
patent: 5225890 (1993-07-01), Lee et al.
K. Omura et al., "Phase measuring Ronchi test", Applied Optics, Feb. 1, 1988, vol. 27, No. 3.
D. S. Wan et al., "Ronchi test and a new phase reduction algorithm", Applied Optics, Aug. 1, 1990, vol. 29, No. 22.
K. Patorski et al., "Fringe contrast interpretation for an extended source Ronchi test", Applied Optics, vol. 25, No. 16, Aug. 15, 1986.
G. Schulz et al., "Errors in phase-measurement interferometry with high numerical apertures", Applied Optics, Nov. 1, 1991, vol. 30, No. 31.
Bacchus Jean M.
Durand Eric
Eisenberg Jason D.
Essilor International (Compagnie General d'Optique)
Rosenberger Richard A.
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