Optical system and method

1. An optical system in a video probe assembly, the optical system including:

a plurality of lenses, each having at least one curved surface, configured to refract separate decomposed linearly polarized rays under different refractive indexes to form a plurality of different focal lengths;

a plurality of light modulating elements each configured to modulate a polarization state of the linearly polarized rays proceeding from at least one of the plurality of lenses and passing through the respective light modulating elements in response to a control signal; and

a polarizer element configured to filter out some of the linearly polarized rays proceeding from at least one of the plurality of light modulating elements and passing through the polarizer element; and

an imager located adjacent to the polarizer element to receive polarized rays proceeding from the polarizer element.

2. The optical system of claim 1 , wherein the lenses each include birefringent elements.

3. The optical system of claim 1 , wherein the plurality of light modulating elements include a first light modulating element and a second light modulating element.

4. The optical system of claim 3 , wherein the plurality of lenses includes a first lens and a second lens.

5. The optical system of claim 4 , wherein the first light modulating element is positioned between the first lens and the second lens.

6. The optical system of claim 5 , wherein the second light modulating element is positioned between the second lens and the polarizer element.

7. The optical system of claim 1 , wherein the linearly polarized rays passing through the plurality of lenses are configured to produce at least four different focal lengths.

8. The optical system of claim 1 , wherein the polarizer element is rotatable.

9. The optical system of claim 8 , wherein the rotation of the polarizer element is configured to filter out at least some of the linearly polarized rays.

10. The optical system of claim 1 , wherein the linearly polarized rays include ordinary ray light and extra-ordinary ray light.

11. An optical system in a video probe assembly, the optical system including:

a plurality of lenses, each having at least one curved surface, configured to refract separate linearly polarized rays under different refractive indexes to form a plurality of different focal lengths;

at least one light modulating element configured to modulate a polarization state of the linearly polarized rays passing through the at least one light modulating element in response to a control signal; and

a rotatable polarizer element configured to filter out some of the linearly polarized rays passing through the polarizer element; and

an imager located adjacent to the polarizer element to receive polarized rays proceeding from the polarizer element.

12. The optical system of claim 11 , wherein the lenses each include birefringent elements.

13. The optical system of claim 12 , wherein the at least one light modulating element includes a first light modulating element and a second light modulating element.

14. The optical system of claim 13 , wherein the plurality of lenses includes a first lens and a second lens.

15. The optical system of claim 14 , wherein the first light modulating element is positioned between the first lens and the second lens.

16. The optical system of claim 15 , wherein the second light modulating element is positioned between the second lens and the polarizer element.

17. The optical system of claim 16 , wherein the linearly polarized rays passing through the plurality of lenses are configured to produce at least four different focal lengths.

18. The optical system of claim 11 , wherein the rotation of the polarizer element is configured to filter out at least some of the linearly polarized rays.

19. A method of inspecting a target with an optical system of a video probe assembly, the method including:

providing a plurality of lenses, each having at least one curved surface, for refracting separate decomposed linearly polarized rays under different refractive indexes to form a plurality of different focal lengths;

directing the linearly polarized rays through at least one light modulating element; and

focusing the linearly polarized rays proceeding from a polarizer element onto an imager.

20. The method of claim 19 , further including the steps of:

refracting one of the linearly polarized rays by a first refractive index;

refracting another of the linearly polarized ray by a second refractive index; and

modulating a polarization state of the linearly polarized rays.