JPH10197797A5

JPH10197797A5 -

Info

Publication number: JPH10197797A5
Application number: JP1997000178A
Authority: JP
Filing date: 1997-01-06
Publication date: 2004-08-19

Claims

An imaging optical system comprising two groups: a group including a decentered optical system having at least one surface with a rotationally asymmetric surface shape that has no axis of rotational symmetry either in-plane or out-of-plane as a curved surface constituting the decentered optical system, and one positive or negative lens group, which corrects rotationally asymmetric aberrations generated by decentering with the rotationally asymmetric surface shape.

An imaging optical system having a group having a decentered optical system, the decentered optical system having at least one surface with a rotationally asymmetric surface shape that has no axis of rotational symmetry either in-plane or out-of-plane as a curved surface constituting the decentered optical system, and which corrects rotationally asymmetric aberrations caused by decentering with the rotationally asymmetric surface shape, and another lens group, wherein the magnification is changed by changing the spacing between the two groups.

3. An imaging optical system according to claim 1, wherein said decentered optical system comprises a reflecting surface having a total reflection function or a reflecting function.

When a ray that emerges from the object point center, passes through the pupil center, and reaches the image center is defined as an axial chief ray, the direction within the decentered surface is defined as the Y-axis direction, the direction perpendicular to this is defined as the X-axis direction, and the axis that constitutes a Cartesian coordinate system together with the X and Y axes is defined as the Z-axis, and when the difference between the value of tan in the Y-Z plane of the normal to at least one rotationally asymmetric surface at the position where the maximum angle of view chief ray in the X direction hits the surface and the value of tan in the Y-Z plane of the normal to the surface at the position where the axial chief ray hits the surface is defined as DY,
0.00001<|DY|<0.1...(2-1)
4. The imaging optical system according to claim 1, wherein the following condition is satisfied:

When the Y-axis direction is the direction within the decentered surface of the surface, the direction perpendicular to the Y-axis direction is the X-axis direction, and the axis that forms a Cartesian coordinate system together with the X-axis and Y-axis is the Z-axis, and the ratio of the curvature in the X-axis of a portion where the chief ray of the maximum angle of view in the Y-positive direction within the decentered surface (Y-Z plane) of at least one rotationally asymmetric surface strikes the surface to the chief ray of the maximum angle of view in the Y-negative direction is Cxn,
0<|Cxn|<1...(3-1)
Or,
1<|Cxn|<10...(3-2)
5. The imaging optical system according to claim 1, wherein the following condition is satisfied:

Let Fgi be the focal length of the ith lens group from the object side that does not include a rotationally asymmetric surface, and Fx be the focal length of the entire optical system with respect to a ray in the X direction perpendicular to the decentered surface.
0.01<|Fgi/Fx|<100...(4-1)
6. The imaging optical system according to claim 1, wherein the following condition is satisfied:

Let us assume that the ray that emerges from the object point center, passes through the pupil center, and reaches the image center is the axial chief ray, the direction within the decentered surface is the Y-axis direction, the direction perpendicular to this is the X-axis direction, and the axis that constitutes a Cartesian coordinate system with the X-axis and Y-axis is the Z-axis. Then, let a parallel beam of light that is separated by an infinitesimal amount d in the X-direction from the principal ray be incident on the entrance surface side of the entire optical system, and let NA'X be the sin of the angle between the two rays when projected onto the X-Z plane on the exit side of the optical system, and let Px be the power in the X direction when NA'X is divided by the width d of the parallel beam of light, and let Pxn be the power in the X direction of the portion of the rotationally asymmetric surface that is hit by the axial chief ray.
0.0001<|Pxn/Px|<1000...(5-1)
7. The imaging optical system according to claim 1, wherein the following condition is satisfied:

Let us assume that the ray that emerges from the object point center, passes through the pupil center, and reaches the image center is the axial chief ray, the direction within the decentered surface is the Y-axis direction, the direction perpendicular to this is the X-axis direction, and the axis that constitutes a Cartesian coordinate system together with the X and Y axes is the Z-axis. Then, let a parallel beam of light that is separated from the principal ray by an infinitesimal amount d in the Y direction be incident on the entrance surface side of the entire optical system, and let NA'Y be the sin of the angle between the two rays when projected onto the Y-Z plane on the exit side of the optical system, and let Py be the power in the Y direction when NA'Y is divided by the width d of the parallel beam of light, and let Pyn be the power in the Y direction of the portion of the rotationally asymmetric surface that is hit by the axial chief ray.
0.0001<|Pyn/Py|<1000...(6-1)
8. The imaging optical system according to claim 1, wherein the following condition is satisfied:

When a light ray that emerges from the object point center, passes through the pupil center, and reaches the image center is defined as an axial chief ray, the Y-axis direction within the decentered surface, the direction perpendicular to this is defined as the X-axis direction, and the Z-axis is defined as an axis that constitutes a Cartesian coordinate system together with the X and Y axes, a parallel beam of light that is spaced apart from the principal ray by an infinitesimal amount d in the X direction is incident on the entrance surface side of the entire optical system, and the sine of the angle formed by the two light rays when projected onto the X-Z plane on the side where the optical system emerges is defined as NA'X, and the value obtained by dividing NA'X by the width d of the parallel beam of light is defined as power Px in the X direction, and when a parallel beam of light that is spaced apart from the principal ray in the Y direction is incident on the optical system, and the sine of the angle formed by the two light rays when projected onto the Y-Z plane on the side where the optical system emerges is defined as NA'Y, and the value obtained by dividing NA'Y by the width d of the parallel beam of light is defined as power Py in the Y direction,
0.1<Px/Py<10...(7-1)
9. The imaging optical system according to claim 1, wherein the following condition is satisfied:

10. The imaging optical system according to claim 1, wherein the surface of the decentered optical system comprises a first reflecting surface, a first transmitting surface, and a second transmitting surface, and a light ray enters the optical system from the first transmitting surface, is reflected by the first reflecting surface, is transmitted through the second transmitting surface, and emerges in a direction different from when the light ray entered the first transmitting surface.