Prism optical system

• US 6,278,556 B1
• Filed: 12/13/1999
• Issued: 08/21/2001
• Est. Priority Date: 08/28/1996
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Togino, Takayoshi
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/458,704
• Time in Patent Office: 617 Days
• Field of Search: 359/637, 359/631, 359/633, 359/627, 359/730, 359/731, 396/352, 353/70
• US Class Current: 359/637
• CPC Class Codes: G02B 17/045 having static image erecting or reversing properties only optical derotators G02B27/642; optical devices for controlling the direction of light using movable or deformable optical elements G02B26/08
• CPC Class Codes: G02B 17/0848 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 17/0896 with variable magnification or multiple imaging planes, including multispectral systems systems with only refractive elements G02B15/14

Abstract

The invention provides a prism optical system which has an image-forming action and provides a clear yet substantially undistorted image at a wide field angle. In a prism optical system 5 comprising an aperture 1 and having an action on erecting an image formed by an objective, there are provided reflecting surfaces 31, 32, 33, 41, 42, and 43 for image inversion, each of which is constructed of a curved surface having a power, and is in an irrotationally symmetric plane shape having no rotationally symmetric axis both within and outside the surface, so that decentering aberration produced by reflection of light at the curved surfaces can be corrected.

Claims

1. A prism optical system for image inversion comprising at least two prisms, wherein:

at least one of said prisms is constructed of a curved surface having at least two surfaces of a rotationally asymmetric surface shape and having no rotationally symmetric axis both within and outside said surfaces,

at least one of said at least two surfaces acting as a reflecting surface having a reflecting action to make correction for rotationally asymmetric aberration produced due to decentering by said rotationally asymmetric surface shape, and

said inverting prism optical system having a finite focal length so as to act as an ocular optical system.

2. The prism optical system of claim 1, which has an optical path substantially identical with that in a Schmidt prism, and in which one of said two prisms has a substantially intersecting optical path and comprises a roof surface, whereas another prism has an optical path that does not intersect.

3. The prism optical system of claim 2, which includes on an objective side thereof a prism having a substantially intersecting optical path and comprising a roof surface, and on an observer'"'"'s pupil side thereof a prism having an optical path that does not intersect.

5. The prism optical system of any one of claims 1 to 4, which has a curved surface shape having only one symmetric plane wherein, on condition that said rotationally asymmetric surface is defined by polynomial (a) given below, a coefficient C_m[Xⁿ⁺¹] with respect to an odd-numbered term for x or xⁿ⁺¹ where n is an integer satisfies condition (30):

$\begin{array}{cc}{C}_m<br><br>\left[x^{n+1}\right]=0& \left(30\right)\\ \begin{array}{c}Z=\text{\hspace{1em}<br><br>}<br><br>C_2+C_3<br><br>y+C_4<br><br>x+C_5<br><br>y^2+C_6<br><br>\mathrm{yx}+C_7<br><br>x^2+C_8<br><br>y^3+\\ \text{\hspace{1em}<br><br>}<br><br>C_9<br><br>y^2<br><br>x+C_{10}<br><br>{\mathrm{yx}}^2+C_{11}<br><br>x^3+C_{12}<br><br>y^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{13}<br><br>y^3<br><br>x+C_{14}<br><br>y^2<br><br>x^2+C_{15}<br><br>{\mathrm{yx}}^3+C_{16}<br><br>x^4+C_{17}<br><br>y^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{18}<br><br>y^4<br><br>x+C_{19}<br><br>y^3<br><br>x^2+C_{20}<br><br>y^2<br><br>x^3+C_{21}<br><br>{\mathrm{yx}}^4+C_{22}<br><br>x^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{23}<br><br>y^6+C_{24}<br><br>y^5<br><br>x+C_{25}<br><br>y^4<br><br>x^2+C_{26}<br><br>y^3<br><br>x^3+C_{27}<br><br>y^2<br><br>x^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{28}<br><br>{\mathrm{yx}}^5+C_{29}<br><br>x^6+C_{30}<br><br>y^7+C_{31}<br><br>y^6<br><br>x+C_{32}<br><br>y^5<br><br>x^2+\\ \text{\hspace{1em}<br><br>}<br><br>C_{33}<br><br>y^4<br><br>x^3+C_{34}<br><br>y^3<br><br>x^4+C_{35}<br><br>y^2<br><br>x^5+C_{36}<br><br>{\mathrm{yx}}^6+C_{37}<br><br>x^7<br><br>\mathrm{\dots <br><br>}\end{array}& \left(a\right)\end{array}$

where C_m is a coefficient provided that m is an integer of 2 or more.

6. The prism optical system of any one of claims 1 to 4, which has a curved surface shape having only one substantially symmetric plane wherein, on condition that said rotationally asymmetric surface is defined by polynomial (a) given below, a coefficient C_m[xⁿ⁺¹] with respect to an odd-numbered term for x or xⁿ⁺¹ where n is an integer satisfies condition (31):

$\begin{array}{cc}-5.0\times <br><br>{10}^{-4}<<br><br>C_m<br><br>\left[x^{n+1}\right]<<br><br>5.0\times <br><br>{10}^{-4}& \left(31\right)\\ \begin{array}{c}Z=\text{\hspace{1em}<br><br>}<br><br>C_2+C_3<br><br>y+C_4<br><br>x+C_5<br><br>y^2+C_6<br><br>\mathrm{yx}+C_7<br><br>x^2+C_8<br><br>y^3+\\ \text{\hspace{1em}<br><br>}<br><br>C_9<br><br>y^2<br><br>x+C_{10}<br><br>{\mathrm{yx}}^2+C_{11}<br><br>x^3+C_{12}<br><br>y^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{13}<br><br>y^3<br><br>x+C_{14}<br><br>y^2<br><br>x^2+C_{15}<br><br>{\mathrm{yx}}^3+C_{16}<br><br>x^4+C_{17}<br><br>y^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{18}<br><br>y^4<br><br>x+C_{19}<br><br>y^3<br><br>x^2+C_{20}<br><br>y^2<br><br>x^3+C_{21}<br><br>{\mathrm{yx}}^4+C_{22}<br><br>x^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{23}<br><br>y^6+C_{24}<br><br>y^5<br><br>x+C_{25}<br><br>y^4<br><br>x^2+C_{26}<br><br>y^3<br><br>x^3+C_{27}<br><br>y^2<br><br>x^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{28}<br><br>{\mathrm{yx}}^5+C_{29}<br><br>x^6+C_{30}<br><br>y^7+C_{31}<br><br>y^6<br><br>x+C_{32}<br><br>y^5<br><br>x^2+\\ \text{\hspace{1em}<br><br>}<br><br>C_{33}<br><br>y^4<br><br>x^3+C_{34}<br><br>y^3<br><br>x^4+C_{35}<br><br>y^2<br><br>x^5+C_{36}<br><br>{\mathrm{yx}}^6+C_{37}<br><br>x^7<br><br>\mathrm{\dots <br><br>}\end{array}& \left(a\right)\end{array}$

where C_m is a coefficient provided that m is an integer of 2 or more.

7. The prism optical system of any one of claims 1 to 4, which has a symmetric plane-free asymmetric polynominal surface or APS wherein, on condition that said rotationally asymmetric surface is defined by polynomial (a) given below, a coefficient C_m[xⁿ⁺¹] with respect to an odd-numbered term for x or xⁿ⁺¹ where n is an integer satisfies condition (32-1) or (32-2):

$\begin{array}{cc}-1.0\times <br><br>{10}^{10}<<br><br>C_m<br><br>\left[x^{n+1}\right]<<br><br>1.0\times <br><br>{10}^{10}& \text{(32-1)}\\ \mathrm{Cm}<br><br>\left[x^{n+1}\right]\ne <br><br>0& \text{(32-2)}\\ \begin{array}{c}Z=\text{\hspace{1em}<br><br>}<br><br>C_2+C_3<br><br>y+C_4<br><br>x+C_5<br><br>y^2+C_6<br><br>\mathrm{yx}+C_7<br><br>x^2+C_8<br><br>y^3+\\ \text{\hspace{1em}<br><br>}<br><br>C_9<br><br>y^2<br><br>x+C_{10}<br><br>{\mathrm{yx}}^2+C_{11}<br><br>x^3+C_{12}<br><br>y^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{13}<br><br>y^3<br><br>x+C_{14}<br><br>y^2<br><br>x^2+C_{15}<br><br>{\mathrm{yx}}^3+C_{16}<br><br>x^4+C_{17}<br><br>y^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{18}<br><br>y^4<br><br>x+C_{19}<br><br>y^3<br><br>x^2+C_{20}<br><br>y^2<br><br>x^3+C_{21}<br><br>{\mathrm{yx}}^4+C_{22}<br><br>x^5+\\ \text{\hspace{1em}<br><br>}<br><br>C_{23}<br><br>y_6+C_{24}<br><br>y^5<br><br>x+C_{25}<br><br>y^4<br><br>x^2+C_{26}<br><br>y^3<br><br>x^3+C_{27}<br><br>y^2<br><br>x^4+\\ \text{\hspace{1em}<br><br>}<br><br>C_{28}<br><br>{\mathrm{yx}}^5+C_{29}<br><br>x^6+C_{30}<br><br>y^7+C_{31}<br><br>y^6<br><br>x+C_{32}<br><br>y^5<br><br>x^2+\\ \text{\hspace{1em}<br><br>}<br><br>C_{33}<br><br>y^4<br><br>x^3+C_{34}<br><br>y^3<br><br>x^4+C_{35}<br><br>y^2<br><br>x^5+C_{36}<br><br>{\mathrm{yx}}^6+C_{37}<br><br>x^7<br><br>\mathrm{\dots <br><br>}\end{array}& \left(a\right)\end{array}$

where C_m is a coefficient provided that m is an integer of 2 or more.

8. The prism optical system of claim 2 or 3, which satisfies condition (1):

9. The prism optical system of claim 2 or 3, which satisfies condition (2):

10. The prism optical system of any one of claims 1 to 4, which comprises at least four reflecting surfaces.

11. The prism optical system of claim 10 in which a fourth surface having a reflecting action or a fourth reflecting surface, as counted from an object side of said prism optical system, has both a reflecting action and a transmitting action.

12. The prism optical system of claim 10, in which a fourth reflecting surface is constructed of a total reflecting surface.

13. The prism optical system of claim 12, which satisfies condition (9):

14. The prism optical system of claim 12, which satisfies condition (10):

15. The prism optical system of any one of claims 1 to 4, which comprises three reflecting surfaces.

16. The prism optical system of claim 15, which satisfies condition (17):

17. The prism optical system of claim 15, which satisfies condition (19):

18. The prism optical system of claim 15, which satisfies condition (21):

19. The prism optical system of claim 15, which satisfies condition (23):

4. A prism optical system for image inversion comprising at least two prisms, wherein:

at least one of said prisms is constructed of a curved surface having at least two surfaces of a rotationally asymmetric surface shape and having no rotationally symmetric axis both within and outside said surfaces,

at least one of said at least two surfaces acting as a reflecting surface having a reflecting action to make correction for rotationally asymmetric aberration produced due to decentering by said rotationally asymmetric surface shape, and

said inverting prism optical system having a finite focal length so as to act as an ocular optical system, and comprising a diffusing surface in the vicinity of a primary image-forming position therein.