Pattern-based optical lens testing apparatus having a module comparing a viewed image representation to a copy of target pattern and method for using the same
View Patent ↗A pattern method is provided for testing an optical lens. The method provides a lens for test, including a first lens surface with a focal plane in object space and a second lens surface with a focal plane in image space. Also provided is a pattern test fixture including an imaging device and a target pattern. The lens is positioned so that the imaging device is located outside the object space focal plane and the target pattern located is outside the image space focal plane. The imaging device, such as a microscope, magnification device, human eye, or camera, is used to view the target pattern. A viewed image representation of the target pattern is received in the imaging device and compared to the target pattern. More typically, the viewed image representation is compared to a target pattern copy.
1. An optical lens test fixture comprising:
a lens clamping mechanism to locate a lens in a test position, the lens including a first lens surface with a focal plane in object space and a second lens surface with a focal plane in image space;
a target pattern located outside the image space focal plane;
an imaging device located outside the object space focal plane, to accept a viewed image representation of the target pattern; and
a calculation module comparing the viewed image representation to a copy of the target pattern stored in a memory.
2. The test fixture of claim 1 wherein the imaging device is selected from a group consisting of a magnification instrument and a camera.
3. The test fixture of claim 1 wherein the calculation module records the viewed image representation and subtracts the target pattern copy from the viewed image representation.
4. The test fixture of claim 1 wherein the calculation module records the viewed image representation and subtracts the target pattern copy from the viewed image representation, creating a subtracted pattern, the calculation module measuring the surface area in the subtraction pattern of a region selected from a group consisting of opaque lines and transparent spaces between lines, and comparing the measured surface area with a maximum threshold.
5. The test fixture of claim 1 wherein the calculation module records the viewed image representation and adds the target pattern copy to the viewed image representation, creating an addition pattern, the calculation module measuring the surface area in the addition pattern of a region selected from a group consisting of opaque lines and transparent spaces, and comparing the measured surface area with a maximum threshold.
6. The test fixture of claim 1 wherein the target pattern is a grid pattern of opaque lines and spaces between the lines.
7. The test fixture of claim 1 wherein the calculation, module compares a geometric feature in the target pattern copy to a predetermined modified geometric feature in the viewed image representation.
8. The test fixture of claim 7 wherein the calculation module compares a third order curve in the target pattern copy to a straight line in the viewed image representation.
9. The test fixture of claim 1 further comprising:
the calculation module having an interface to accept the viewed image representation and measuring intensity of the viewed image representation.
10. The test fixture of claim 1 wherein the calculation module compares chromatic offsets in the viewed image representation to the target pattern copy.
11. The test fixture of claim 1 wherein the imaging device includes an optical transformation means and supplies a viewed image representation processed by the optical transformation means: and,
wherein the calculation module compares the target pattern copy, modified to account for the imaging device optical transformation, to the processed viewed image representation.
12. A pattern method for testing an optical lens, the method comprising:
providing a lens including a first lens surface with a focal plane in object space and a second lens surface with a focal plane in image space;
providing a pattern test fixture including an imaging device and a target pattern, wherein the target pattern comprises a predetermined geometric feature, the predetermined geometric feature based at least in part on an optical characteristic of the lens;
positioning the lens so that the imaging device is located outside the object space focal plane and the target pattern located outside the image space focal plane;
using the imaging device to view the target pattern;
receiving a viewed image representation of the target pattern in the imaging device; and,
comparing the viewed image representation to the target pattern.
13. The method of claim 12 wherein the imaging device is selected from a group consisting of a magnification instrument and a camera.
14. The method of claim 12 wherein comparing the viewed image representation to the target pattern includes comparing the viewed image representation to a target pattern copy.
15. The method of claim 14 wherein comparing the viewed image representation to the target pattern copy includes:
recording the viewed image representation; and,
subtracting the target pattern copy from the recorded image representation.
16. The method of claim 14 wherein comparing the viewed image representation to the target pattern copy includes:
recording the viewed image representation;
subtracting the target pattern copy from the recorded image representation, creating a subtracted pattern;
measuring the surface area in the subtracted pattern of a region selected from a group consisting of lines and spaces between lines; and,
comparing the measured surface area with a maximum threshold.
17. The method of claim 14 wherein comparing the image pattern to the target pattern copy includes:
recording the viewed image representation;
adding the target pattern copy to the recorded image representation, creating a summed pattern;
measuring the surface area in the summed pattern of a region selected from a group consisting of opaque lines and transparent spaces; and,
comparing the measured surface area with a maximum threshold.
18. The method of claim 12 wherein providing the target pattern includes providing a grid pattern of lines and spaces between the lines.
19. The method of claim 12 wherein comparing the viewed image representation to the target pattern includes comparing the predetermined geometric feature in the target pattern to a modified geometric feature in the viewed image representation.
20. The method of claim 19 wherein comparing the geometric feature in the target pattern to the modified geometric feature in the viewed image representation includes comparing a third order curve in the target pattern to a straight line in the viewed image representation.
21. The method of claim 12 wherein comparing the viewed image representation to the target pattern includes measuring the total intensity of light accepted by the imaging device.
22. The method of claim 12 wherein providing the lens includes providing a fiber optic cable connector lens body.
23. The method of claim 22 wherein providing the fiber optic cable connector lens body includes providing the lens body with a plurality of lens, each having a first and second surface; and,
wherein comparing the viewed image representation to the target pattern includes sequentially comparing the viewed image representation associated with each lens to the target pattern.
24. The method of claim 12 wherein comparing the viewed image representation to the target pattern includes comparing chromatic offsets in the viewed image representation to the target pattern.
25. The method of claim 12 wherein receiving the viewed image representation of the target pattern in the imaging device includes receiving the viewed image representation of the target pattern in an imaging device having an optical transformation means; and,
wherein comparing the viewed image representation to the target pattern includes comparing the target pattern to a viewed image representation modified to account for the imaging device optical transformation.