Beam-splitting optical system

• US 4,288,148 A
• Filed: 08/29/1979
• Issued: 09/08/1981
• Est. Priority Date: 08/29/1979
• Status: Expired due to Term

• Current Assignee: Bristol-Myers Squibb Company
• Original Assignee: Perkinelmer Incorporated
• Inventors: Markle, David A., Offner, Abe
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Sugarman, Scott J.
• Application Number:
  US06/070,568
• Time in Patent Office: 741 Days
• Field of Search: 350/212, 350/202, 350/175 E, 350/55, 350/230, 350/453, 350/445
• US Class Current: 359/744
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/144 using partially transparent surfaces without spectral selectivity G02B27/147 takes precedence

Abstract

An optical system for insertion into projection apparatus to permit viewing an image projected on an image plane without affecting its quality, size or position, including a beam-splitting element disposed in the optical path before the image plane which will transmit the radiation to the image plane and reflect a portion of the radiation reflected from the image plane in a direction which permits viewing, optical elements disposed in the optical path to correct for image displacement and aberrations caused by the beam-splitting element, said optical system being of unit power; according to one aspect of the invention the system is afocal so that it will remain at unit power when it is shifted longitudinally and the image position is insensitive to longitudinal displacement; and according to another aspect of the invention each element of the system is afocal so that the system remains at unit power and insensitive to changes in spacing between the elements.

Claims

1. A unit power optical system for insertion into projection apparatus to permit viewing an image projected on an image plane without affecting its quality, size or position comprising:

a beam splitting element disposed in the optical path of the converging light before the image plane so that said beam splitting element will transmit the radiation to the image plane and reflect a portion of the radiation reflected from the image plane in a direction which permits viewing;

means disposed in said optical path to correct for image displacement and aberrations caused by said beam splitting element; and

said optical system being afocal so that said system will remain at unit power when it is shifted longitudinally and the image position is insensitive to longitudinal displacement.

2. The optical system according to Claim 1, wherein said means for correcting for image displacement and aberrations comprises first and second meniscus lens elements.

3. An optical system according to Claim 2, further comprising a tiltable plane parallel plate element disposed between the menisus elements for adjusting the position of the image laterally.

4. The optical system according to claim 2 or claim 3, wherein each element of the system is afocal so that the system remains at unit power and insensitive to changes in the spacing between the elements.

5. An optical system according to claim 4, wherein said beam splitting element is disposed in the optical path between said image plane and said meniscus lens elements.

6. An optical system according to claim 2, wherein said beam splitting element is disposed between said menisus lens elements.

7. An optical system according to claim 3, wherein said beam splitting element is disposed between said tiltable plane parallel plate and the second meniscus lens element.

8. An optical system according to claim 7, wherein said system is characterized by the following construction data:

space="preserve" listing-type="tabular">__________________________________________________________________________ GLASS AIR SURFACE RADIUS THICKNESS GLASS INDEX OF REFRACTION SEPARATION NUMBER (mm) (mm) TYPE .5600 μ

m .5200 μ

m .6000 μ

m (mm) __________________________________________________________________________S1 24.48(cx) 3.93 BK-7 1.5180 1.5202 1.5163 S2 23.14(cc) 28.97 S3 ∞

(plane) 2.00 F-2 1.6226 1.6272 1.6190 S4 ∞

(plane) 8.74 S5 ∞

(plane) 7.00 F-2 1.6226 1.6272 1.6190 S6 ∞

(plane) 2.26 S7 14.72(cc) 2.50 BK-7 1.5180 1.5202 1.5163 S8 15.57(cx) 3.00 __________________________________________________________________________ Spectral Range .5200 μ

m ≦

λ

≦

.6000 μ

m and distance from S1 to image plane = 58.4mm and distance from S8 to image plane = 3.0mm.

9. An optical system according to claim 3, wherein said beam splitting element is disposed between said meniscus lens elements.

10. An optical system according to claim 4, wherein said beam splitting element is disposed between said meniscus lens elements.

13. A microprojection system according to claims 1, 11 or 12, wherein said beam splitting element is a beam splitting cube.

11. A microprojection system for forming an image of a mask on a light sensitive wafer, said system comprising:

a beam splitting element disposed in the optical path of the converging light before the image plane so that said beam splitting element will transmit the radiation to the image plane and reflect a portion of the radiation reflected from the image plane in a direction which permits viewing;

first and second meniscus lens elements having their concave surfaces facing each other and being disposed in the optical path to correct for image displacement and aberrations caused by said beam splitting element; and

each of said elements being afocal.

12. A microporojection system according to claim 11 wherein said beam splitting element is disposed in the optical path between said meniscus lens elements;

and said system further comprises a tiltable plane parallel plate element disposed in the optical path between the first meniscus lens and the beam splitting element for adjusting the position of the image laterally.