Image analysis system

• US 5,661,816 A
• Filed: 01/31/1995
• Issued: 08/26/1997
• Est. Priority Date: 10/22/1991
• Status: Expired due to Term

• Current Assignee: Optikos Corporation
• Original Assignee: Optikos Corporation
• Inventors: Carellas, Peter T., Fantone, Stephen D.
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US08/382,517
• Time in Patent Office: 938 Days
• Field of Search: 382/100, 382/321, 356/124, 356/124.5, 356/128, 364/525
• US Class Current: 382/100
• CPC Class Codes: G01M 11/0242 by measuring geometrical properties or aberrations
• CPC Class Codes: G01M 11/0257 by analyzing the image formed by the object to be tested
• CPC Class Codes: G01M 11/0292 of objectives by measuring the optical modulation transfer function photometry G01J

Abstract

A system for quickly measuring and displaying in real-time a variety of performance characteristics of optical components such as lenses. The system is video based and is under the control of a computer which uses a windowing software program to provide the user with a graphical user interface by which the various components of the system and test lenses may be characterized and operated on through functions available via the interface. Lens performance measurements such as line spread and modulation transfer functions can be graphically and numerically displayed in real-time and/or recorded on other output devices or as files in computer memory.

Claims

1. Apparatus for testing optical components in real-time, said apparatus comprising:

means for holding and positioning an optical component for evaluation;

means for presenting an illuminated target to said optical component so that said optical component can form an image of said target in a measurement plane, said target being selected from the group consisting of a pin hole, slit, or edge;

a video camera for viewing said image of said target in said measurement plane and generating a standard video signal thereof whose amplitude varies over the spatial extent of said image in correspondence with its intensity;

a frame grabber for capturing at least one frame of said video signal;

means for digitizing said frame of said video signal as an array of data representative of the spatial variation in said amplitude of said video signal and for at least temporarily storing said array of data; and

means for performing real-time image analysis on said array of data and displaying the results of said image analysis as said image analysis is performed, including generating from said array of data the line spread function of the optical component along at least one azimuth thereof.

2. The apparatus of claim 1 wherein said means for digitizing and storing comprises an analog to digital converter and a memory buffer.

3. The apparatus of claim 2 wherein said video camera includes a two-dimensional array having a predetermined pixel geometry.

4. The apparatus of claim 3 wherein said two-dimensional array comprises a CCD.

5. The apparatus of claim 3 further including optical means for selectively changing the size of said image formed by said optical component as it is presented to said video camera so as to optimize the apparent resolution of said image.

6. The apparatus of claim 1 wherein said means for holding and positioning an optical component for evaluation comprises means for moving said optical component and said video camera relative to one another along at least one of three mutually orthogonal axes one of which coincides with the optical axis of said optical component.

7. The apparatus of claim 6 wherein said means for holding and positioning an optical component for evaluation further comprises means for selectively changing the angular orientation of said optical component relative to said target and said video camera.

8. The apparatus of claim 1 wherein said means for performing image analysis on said data form and displaying the results as said image analysis is performed comprises a computer with a graphical user interface (GUI), said computer comprising means for summing rows and columns of said array of data to generate line spread functions for said optical component and for performing Fourier analysis on said line spread functions to generate modulation transfer function(s), MTF, for said optical components.

9. The apparatus of claim 8 wherein said graphical user interface comprises a video monitor for displaying windows, menus, submenus, dialog boxes, and icons representing apparatus functions and includes a user input device for selecting from said windows, menus, submenus, dialog boxes and icons.

10. The apparatus of claim 9 wherein said computer with said video monitor further graphically displays the measured performance of said optical component.

11. The apparatus of claim 8 wherein said computer further includes means for indicating the part of said image that is used to carry out said image analysis.

12. The apparatus of claim 11 wherein said means for indicating the part of said image that is used comprises a part of a computer graphical user interface including a window that permits the user to select the size and orientation of said part of the image to be used.

13. The apparatus of claim 1 wherein said means for performing image analysis on said array of data and displaying the results as said image analysis is performed comprises means for calculating and displaying the uncorrected and corrected line spread function and MTF of said optical component.

14. The apparatus of claim 13 wherein said means for performing image analysis on said data form and displaying the results as said image analysis is performed comprises means for moving said optical component along at least one axis and performing and displaying said image analysis as said optical component is moved.

15. The apparatus of claim 1 further including means for displaying said image of said component is further configured to display said image as said component is being tested.