Precision double-sided aspheric element

• US 7,028,595 B2
• Filed: 09/22/2003
• Issued: 04/18/2006
• Est. Priority Date: 05/21/1998
• Status: Expired due to Fees

• Current Assignee: Ophir Optronics Solutions Ltd. (MKS Instruments Incorporated)
• Original Assignee: Ophir Otronics Limited
• Inventors: Zerem, Yaacov, Asida, Nissim, Ben-Menachem, Baruch
• Primary Examiner(s): Fridie, Jr., Willmon
• Application Number:
  US10/667,849
• Publication Number:
  US 20040058625A1
• Time in Patent Office: 939 Days
• Field of Search: 82/13, 82/12, 82/13, 82/113, 269/21, 279/3, 351/159
• 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 first 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 method of producing first and second aspheric surfaces on a precision optical element having a radial dimension, comprising the steps of:

forming said first aspheric surface on said element;

forming on a vacuum chuck, a support surface having a width in its radial direction less than 50% of said radial dimension of said element, and having an aspheric form matching that of said first aspheric surface formed on said element; and

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

2. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, wherein at least one of said steps of forming said first aspheric surface and of forming said second aspheric surface of said element comprises a machining step.

3. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, wherein said step of forming on a vacuum chuck a support surface comprises a machining step.

4. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, further comprising the step of machining a diffractive optics pattern on at least one of said aspheric surfaces.

5. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, wherein the precision of said optical element is such that the maximum peak to valley irregularity of at least one of said first and second surfaces is less than one wavelength of red Helium-Neon laser light.

6. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, wherein said support surface has a volume formed radially inside of it, said volume accommodating a vacuum.

7. The method of producing first and second aspheric surfaces on a precision optical element according to claim 1, wherein said vacuum chuck comprises at least one passage within said support surface which accommodates a vacuum.

13. A vacuum chuck for implementing the method of claim 1 for producing first and second aspheric surfaces on a precision optical element, said chuck having a support surface on which said first aspheric surface of said element is seated, said support surface having an aspheric form matching that of said first aspheric surface of said element, and having a width in its radial direction less than 50% of said radial dimension of said element.

14. A vacuum chuck according to claim 13, wherein said support surface has a volume formed radially inside of it, said volume accommodating a vacuum.

15. A vacuum chuck according to claim 13, wherein said support surface is such that a major portion of said first aspheric surface of said element is unsupported when said element is seated in said chuck.

8. A method of producing first and second aspheric surfaces on a precision optical element, comprising the steps of:

forming said first aspheric surface on said element;

forming on a vacuum chuck a support surface having an aspheric form matched to said first aspheric surface formed on said element, said support surface being such that when said element is held in said chuck said support surface is in contact with said first aspheric surface of said element only over a minor part of the complete area of said first aspheric surface; and

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

9. The method of producing first and second aspheric surfaces on a precision optical element according to claim 8, wherein said step of forming said first aspheric surface of said element comprises a machining step.

10. The method of producing first and second aspheric surfaces on a precision optical element according to claim 8, wherein said step of forming on a vacuum chuck a support surface comprises a machining step.

11. The method of producing first and second aspheric surfaces on a precision optical element according to claim 8, further comprising the step of machining a diffractive optics pattern on at least one of said aspheric surfaces.

12. The method of producing first and second aspheric surfaces on a precision optical element according to claim 8, wherein the precision of said optical element is such that the maximum peak to valley irregularity of at least one of said first and second surfaces is less than one wavelength of red Helium Neon laser light.

16. A vacuum chuck for implementing the method of claim 8 for producing first and second aspheric surfaces on a precision optical element, said chuck having a support surface on which said first aspheric surface of said element is seated, said support surface having an aspheric form matching that of said first aspheric surface of said element and being in contact with said first aspheric surface only over a minor part of the complete area of said first aspheric surface.

17. The vacuum chuck of claim 16 wherein said support surface has a volume formed radially inside of it, said volume accommodating a vacuum.

18. The vacuum chuck of claim 16 further comprising at least one passage within said support surface that accommodates a vacuum.

19. An optical system comprising at least one precision optical element, machined in the vacuum chuck of claim 16.

20. The vacuum chuck of claim 16 wherein said support surface is such that a major portion of said first aspheric surface of said element is unsupported when said element is seated in said chuck.