Precision lens mounting

• US 4,733,945 A
• Filed: 01/15/1986
• Issued: 03/29/1988
• Est. Priority Date: 01/15/1986
• Status: Expired due to Fees

• Current Assignee: SVG Lithography Systems Incorporated (ASML Holding NV)
• Original Assignee: Perkinelmer Incorporated
• Inventors: Bacich, John J.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Ben, Loha
• Application Number:
  US06/818,925
• Time in Patent Office: 804 Days
• Field of Search: 350/253, 350/252, 350/255, 350/247, 350/245, 350/254, 354/286
• US Class Current: 359/820
• CPC Class Codes: G02B 7/02 for lenses supports for magnifying lenses G02B25/002
• CPC Class Codes: G03F 7/70825 Mounting of individual elements, e.g. mounts, holders or supports workpiece or mask holders G03F7/707

Abstract

A precision lens mounting assembly which includes a plurality of lens cells and a plurality of lenses which correspond to the plurality of lens cells. The lens cells have an annular shape. Flexure means are disposed within the inner diameter of the lens cell which hold the lens in a predetermined spatial relation at a datum temperature to the lens cell. The flexure means return the lenses to this predetermined spatial relation following temperature excursions away from, then back to, the datum temperature. The outer diameter of the lens cells in the assembly are all substantially equal and substantially concentric about the optical axis of the lenses they hold. The upper and lower surfaces of the lens cell each have three or more precision surfaces disposed on a plane. The plane are perpendicular to the optical axis of the lens and have a predetermined spatial relation to the apex of the lens. Selected ones of the lens cells can be rotated, translated or moved axially with respect to the other lens cells in the lens assembly to correct for astigmatism, coma or spherical aberrations, respectively. Adhesive means are provided to hold the plurality of the lens cells together.

Claims

1. A precision lens mounting assembly comprising:

a plurality of lens cells;

a plurality of lenses corresponding to said plurality of lens cells;

said lens cells each having an inner diameter, an outer diameter, a top surface and a bottom surface;

flexure means disposed within the inner diameter of each of said plurality of lens cells to hold an individual lens in a predetermined spatial relation at a datum temperature to said inner diameter, said top surface and said bottom surface;

said flexure means returning said individual lens to said predetermined spatial relation following temperature excursions away from then back to said datum temperature;

the outer diameter of said plurality of lens cells being substantially equal to each other and substantially concentric about the optical axis of their respective individual lenses;

the upper and lower surfaces of each lens cell having three or more precision surfaces disposed on a plane substantially perpendicular to the optical axis of said individual lens, said plane having a predetermined spatial relation to the vertex of said individual lens; and

said plurality of lens cells forming a stack of lens cells substantially in contact at said precision surfaces.

2. A precision lens mounting assembly as claimed in claim 1 wherein said stack of lens cells comprises:

a bottom lens cell;

a cap lens cell; and

one or more groups of lens cells disposed between said bottom and said cap lens cells.

3. A precision lens mounting assembly as claimed in claim 2 which further comprises holding means to hold said stack of lens cells substantially in contact at said precision surfaces.

4. A precision lens mounting assembly as claimed in claim 3 wherein said holding means comprises:

one or more groups of lens cells comprising an anchor lens cell, one or more individual lens cells and a top lens cell;

at least two dowels fixed to the top surface of said anchor lens cell;

said one or more individual lens cell having bores therethrough for receiving said dowels;

said top lens cell having bores therethrough for receiving said dowels;

said top lens cell having at least two dowels fixed to the top surface thereof to fix the next group of individual lens cells thereto;

5. A precision lens mounting assembly as claimed in claim 4 which further includes:

a bottom anchor cell in said stack of lens cells having at least two bottom conical dowels fixed to the bottom surface thereof;

said bottom lens cell having bores therethrough for receiving said bottom conical dowels;

a top group of lens cells wherein the top lens cell in said top group of lens cells has at least two top conical dowels fixed to the top surface thereof;

said cap lens cell having bores therethrough for receiving said top conical dowels;

said top and bottom conical dowels having an outside diameter smaller than the inside diameter of the bores;

epoxy disposed between said top and bottom conical dowels and the bores through said cap lens cell and said bottom lens cell, respectively; and

seals to prevent said epoxy from escaping from the bores.

6. A precision lens mounting assembly as claimed in claim 1 which further includes:

spacing adjustment means to adjust the axial spacing between selected ones of said lens cells.

7. A precision lens mounting assembly as claimed in claim 6 wherein said spacing adjusting means comprises a shim, said shim having a top precision surface substantially in contact with the precision surfaces on the bottom surface of a first selected one of said lens cells and a bottom precision surface substantially in contact with the precision surfaces on the top surface of a second selected one of said lens cells.

8. A precision lens mounting assembly as claimed in claim 6 wherein said spacing adjusting means comprises:

at least three threaded holes extending radially inward from the outer diameter of selected ones of said lens cells;

at least three tapered screws extending into the threaded holes;

axial moving means disposed on the upper surface of said selected ones of said lens cells; and

said tapered screws being radially translatable within the threaded holes to encounter said axial moving means, said axial moving means moving axially when said tapered screws are moved inwardly radially.

9. A precision lens mounting assembly as claimed in claim 8 wherein said axial moving means comprises:

at least three balls corresponding to at least three through bores, each ball being disposed in a through bore, each through bore intersecting each threaded hole; and

said balls resting on said tapered screws

10. A precision lens mounting assembly as claimed in claim 8 wherein said axial moving means comprises:

tapered cantilevered beams each having a top surface, a bottom tapered surface, a free end and a fixed end;

the top surface of each tapered cantilevered beam being substantially flush with the upper surface of each lens cell;

the bottom tapered surface of said tapered cantilevered beam contacting tapered screw extending radially inwardly from the threaded hole;

the fixed end of the tapered cantilevered beam being substantially at the inner diameter of said lens cell;

said tapered cantilevered beam extending radially outwardly from said inner diameter of said lens cell; and

a half ball, said half ball being disposed on the top surface of said tapered cantilevered beam.

11. A precision lens mounting assembly as claimed in claim 1 wherein said flexure means comprises:

at least three arcuate cantilevered arms integrally formed in said lens cells, each arm having a free end and a fixed end, the outer walls of said arms being substantially flush with said inner diameter; and

each of said arcuate cantilevered arms having lens seats distal said fixed end to support said individual lens in respective lens cells.

12. A precision lens mounting assembly as claimed in claim 1 which further includes:

said lens seat extending radially inwardly from said lens cell inner diameter;

said lens seat having a trough therein; and

adhesive disposed in said trough to adheringly hold said individual lens.

13. A precision lens mounting assembly as claimed in claim 11 wherein said arcuate cantilevered arms each have a narrow section extending from said lens seat towards said fixed end for a short distance.

14. A precision lens mounting assembly as claimed in claim 13 which further includes:

said lens seat extending radially inwardly from said lens cell inner diameter;

said lens seat having a trough therein; and

adhesive disposed in said trough to adheringly hold said individual lens.

15. A precision lens mounting assembly, as claimed in claim 1 wherein said flexure means comprises:

an articulated flexure integrally formed in each of said lens cells;

said articulated flexure comprising a first arm located radially inwardly from said inner diameter of the lens cell joined at said bottom surface of the lens cell, said first arm extending axially to a joint at substantially said top surface;

a second arm having an outer wall flush with said inner diameter, extending axially from said joint to substantially said bottom surface; and

a lens seat extending radially inwardly from said second arm distal said joint to support said individual lens in its respective lens cell.

16. A precision lens mounting assembly as claimed in claim 15 which further includes:

said lens seat having a trough therein; and

adhesive disposed in said trough to adheringly hold said individual lens.

17. A precision lens mounting assembly as claimed in claim 1 wherein said flexure means comprises:

at least three arcuate cantilevered arms integrally formed in said lens cells, each arm having a free end and a fixed end, the outer walls of said arms being substantially flush with said inner diameter;

each of said arcuate cantilevered arms having a hole therethrough distal said fixed end;

said lens cell having radial ports therethrough corresponding to the holes in each of said arcuate cantilevered arms;

adhesive disposed between said arcuate cantilevered arms and the circumference of said individual lens to adheringly hold said individual lens; and

said adhesive being disposed substantially at the holes in said arcuate cantilevered arms.

18. A precision lens mounting assembly as claimed in claim 17 which further comprises:

said arcuate cantilevered arm having a projection land integral therewith;

said projection land projecting radially inwardly from said arcuate cantilevered arm distal said fixed end;

the hole extending through said projection land; and

said adhesive being disposed between said projection land and said lens.

19. A precision lens mounting apparatus comprising:

a lens cell insert having an inner diameter, a tapered outer diameter, a top surface and a precision machined bottom surface;

a lens;

flexure means disposed within the inner diameter of said lens cell insert to hold said lens in a predetermined spatial relation, at a datum temperature, to said inner diameter, said top surface and said bottom surface; and

said flexure means returning said lens to said predetermined spatial relation following temperature excursions away from, then back to, said datum temperature;

a lens cell having an inner diameter, an outer diameter, a top and a bottom surface;

said lens cell having at least three threaded holes extending from said outer to said inner surface;

three screws corresponding to the three threaded holes in said lens cell;

a precision machined surface extending radially inward from the inner diameter of said lens cell;

the tapered outer diameter of said lens cell insert being less than the inner diameter of said lens cell;

said precision machined bottom surface of said lens cell insert resting on said precision machined surface of said lens cell.

20. A precision lens mounting apparatus comprising:

a lens cell having an inner diameter, an outer diameter, a top surface and a bottom surface;

a lens;

flexure means disposed within the inner diameter of said lens cell to hold said lens in a predetermined spatial relation, at a datum temperature, to said inner diameter, said top surface and said bottom surface; and

said flexure means returning said lens to said predetermined spatial relation following temperature excursions away from, then back to, said datum temperature.

21. A precision lens mounting apparatus as claimed in claim 20 wherein said flexure means comprises:

at least three arcuate cantilevered arms integrally formed in said lens cell, each arm having a free end and a fixed end, the outer walls of said arms being substantially flush with said inner diameter; and

each of said arcuate cantilevered arms having lens seats distal said fixed end for securing said individual lens to respective lens cells.

22. A precision lens mounting apparatus as claimed in claim 21 which further includes:

said lens seat extending radially inwardly from said lens cell inner diameter;

said lens seat having a trough therein; and

adhesive disposed in said trough to adheringly hold said individual lens.

23. A precision lens mounting apparatus as claimed in claim 22 wherein said arcuate cantilevered arms each have a narrow section extending from said lens seat towards said fixed end for a short distance.

24. A precision lens mounting apparatus as claimed in claim 22 wherein said flexure means comprises:

an articulated flexure integrally formed in said lens cell;

said articulated flexure comprising a first arm located radially inwardly from said inner diameter of the lens cell joined at said bottom surface of the lens cell, said first arm extending axially to a joint at substantially said top surface;

a second arm having an outer wall flush with said inner diameter, extending axially from said joint to substantially said bottom surface; and

a lens seat extending radially inwardly from said second arm distal said joint for securing said lens to said lens cell.

25. A precision lens mounting apparatus as claimed in claim 24 which further comprises:

said lens seat having a trough therein; and

adhesive disposed in said trough to adheringly hold said individual lens.

26. A precision lens mounting assembly as claimed in claim 20 wherein said flexure means comprises:

at least three arcuate cantilevered arms integrally formed in said lens cell, each arm having a free end and a fixed end, the outer walls of said arms being substantially flush with said inner diameter;

each of said arcuate cantilevered arms having a hole therethrough distal said fixed end;

said lens cell having radial ports therethrough corresponding to the holes in each of said arcuate cantilevered arms;

adhesive disposed between said arcuate cantilevered arms and the circumference of said lens to adheringly hold said lens; and

said adhesive being disposed substantially at the holes in said arcuate cantilevered arms.

27. A precision lens mounting assembly as claimed in claim 26 which further comprises:

said arcuate cantilevered arm having a projection land integral therewith;

said projection land projecting radially inwardly from said arcuate cantilevered arm distal said fixed end;

the hole extending through said projection land; and

said adhesive being disposed between said projection land and said lens.