Precision double-sided aspheric element

• US 20010029816A1
• Filed: 06/11/2001
• Published: 10/18/2001
• Est. Priority Date: 05/21/1998
• Status: Active Grant

• Current Assignee: Baruch Ben-Menachem, Nissim Asida, Yaacov Zerem
• Original Assignee: Baruch Ben-Menachem, Nissim Asida, Yaacov Zerem
• Inventors: Zerem, Yaacov, Asida, Nissim, Ben-Menachem, Baruch
• Granted Patent: US 6,460,437 B2
• Time in Patent Office: Days
• US Class Current: 82/1.3
• CPC Class Codes: B24B 13/005 Blocking means, chucks or the like; Alignment devices
• CPC Class Codes: B24B 13/046 using a pointed tool or scraper-like tool B24B13/015 and B24B13/065 take precedence
• CPC Class Codes: B24B 41/061 axially supporting turning workpieces, e.g. magnetically, pneumatically
• CPC Class Codes: G02B 13/14 for use with infrared or ultraviolet radiation G02B13/008, G02B13/16 take precedence
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4216 correcting geometrical aberrations
• CPC Class Codes: G02B 27/4227 in image scanning systems
• CPC Class Codes: G02B 27/4277 being separated by an air space
• CPC Class Codes: G02B 3/04 with continuous faces that are rotationally symmetrical but deviate from a true sphere , e.g. so called "aspheric" lenses
• CPC Class Codes: G02B 5/189 Structurally combined with optical elements not having diffractive power
• CPC Class Codes: Y10T 82/10 Process of turning
• CPC Class Codes: Y10T 82/122 Forming non-circular bore
• CPC Class Codes: Y10T 82/125 Tool simultaneously moving axially
• CPC Class Codes: Y10T 82/148 Pivoted tool rest
• CPC Class Codes: Y10T 82/149 Profiled cutter

Abstract

A precision optical element is described, such as is used in thermal imaging systems in the infra-red, manufactured by means of single point machining, with both of its surfaces having an aspheric form, with or without the addition of a diffractive optics pattern. The element is produced while held in a novel vacuum chuck, whose support surface has a width in the radial direction significantly less than the size of the element, and which is aspherically machined to match the aspheric firsts surface of the element. A method whereby such an element can be produced by means of single point machining, such as diamond turning or fly cutting, is also described. Also described are new optical system designs and applications using such double-sided aspheric elements, thereby providing significant improvement over currently available optical systems.

Claims

1. A precision optical element comprising first and second aspheric surfaces, at least one of which is single point machined.

2. A precision optical element according to

claim 1

, and wherein both surfaces are single point machined.

3. A precision optical element according to

claim 1

, and wherein said single point machined surface is produced by means of a diamond tool.

4. A precision optical element according to

claim 1

, and wherein said element is a lens.

5. A precision optical element according to

claim 1

, and wherein said element is a double-sided mirror.

6. A precision optical element according to

claim 1

, and wherein said element comprises an infra-red transparent material.

7. A precision optical element according to

claim 1

, and wherein said element comprises a material selected from the group comprising germanium, zinc selenide, zinc sulphide, gallium arsenide, silicon and calcium fluoride.

8. A precision optical element according to

claim 1

, and wherein said element further comprises a diffractive optics pattern turned on at least one of its surfaces.

9. A precision optical element according to

claim 1

, and wherein the precision of at least one of said first and second surfaces is such that the maximum peak to valley irregularity is less than one wavelength of red Helium Neon laser light.

18. An optical system comprising at least one precision optical element according to

claim 2

.

10. A precision optical element comprising first and second aspheric surfaces, at least one of which is single point machined, and which further comprises a diffractive optics pattern machined on at least one of its surfaces.

11. A precision optical element according to

claim 10

, and wherein both surfaces are single point machined.

12. A method of producing first and second aspheric surfaces on a precision optical element having a radial size, at least said second aspheric surface being produced by means of single point machining, and comprising the steps of:

forming said first aspheric surface on said element;

forming on a vacuum chuck, a support surface of width in its radial direction significantly smaller than said radial size of said element, and having an aspheric form matching said first aspheric surface formed on said element; and

subsequently machining said second aspheric surface on said element while it is held by said first aspheric surface in said vacuum chuck.

13. A method of producing first and second aspheric surfaces on a precision optical element according to

claim 12

, and wherein said step of forming said first aspheric surface of said element comprises a machining step.

14. A method of producing first and second aspheric surfaces on a precision optical element according to

claim 12

, and wherein said step of forming on a vacuum chuck a support surface comprises a machining step.

15. A method of producing first and second aspheric surfaces on a precision optical element according to

claim 12

, and also comprising the step of machining a diffractive optics pattern on at least one of said surfaces.

16. A method of producing first and second aspheric surfaces on a precision optical element according to

claim 12

, and wherein the precision of said optical element is such that the maximum peak to valley irregularity of at least one of its first and second surfaces is less than one wavelength of red Helium Neon laser light.

19. An optical system comprising at least one precision optical element produced by means of the method according to

claim 12

.

17. An optical system comprising at least one precision optical element comprising two aspheric surfaces, at least one of which is single point machined.

20. An optical system according to

claim 17

, and wherein said at least one precision optical element also comprises a diffractive optics pattern on at least one surface.

21. An optical system according to

claim 17

, for use in thermal imaging applications.

22. An optical system according to

claim 17

, and wherein the precision of said optical element is such that the maximum peak to valley irregularity of at least one of its first and second surfaces is less than one wavelength of red Helium Neon laser light.

23. A vacuum chuck for holding a precision optical element having a radial dimension and a first aspheric surface, for single point machining of a second aspheric surface thereon, and comprising a support surface of width significantly smaller than said radial dimension, said support surface having an aspheric form matching that of said first aspheric surface of said element.

24. A vacuum chuck according to

claim 23

, and wherein the volume inside of said support surface accommodates a vacuum.

25. A vacuum chuck according to

claim 23

, and comprising at least one passage within said support surface which accommodates a vacuum.

26. An optical system comprising at least one precision optical element, machined in a vacuum chuck according to

claim 23

.