JP2005283717A - Variable magnification optical system and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable magnification optical system which varies magnification by changing an optical functional surface passing position of a luminous flux by rotating the optical functional surface, and does not need to shift an imaging device to be arranged on an image plane. <P>SOLUTION: The variable magnification optical system is provided with one or more optical elements 10 having at least one or more uni-plane optical functional surfaces 11, 12, 13 from an aperture 2 toward an object side, and forms an image of a distant object O with a variable magnification, and at least one surface 12 of the uni-plane optical functional surfaces comprises a continuous surface and is constituted in a form of which at least the radius of curvature in the cross-sectional direction continuously varies from one end toward the other end of the cross section, and when varying the magnification, the magnification is varied by rotating one optical element 10 having the uni-plane optical functional surfaces 11, 12, 13 centering a point S not coming into contact with one of the uni-plane optical functional surfaces. The image plane 3 is fixed with respect to the aperture 2 or moves in a fixed plane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable magnification optical system and an electronic apparatus using the same, and more particularly to a compact variable magnification optical system and an electronic apparatus using such a variable magnification optical system. Examples of the electronic apparatus include a digital camera, a video camera, a digital video unit, a personal computer, a mobile computer, a mobile phone, and an information portable terminal.

Patent Document 1, Patent Document 2, Patent Document 3 and the like are known as a variable magnification imaging optical system that includes a free-form surface prism.
JP-A-8-292372 JP 2002-139670 A JP 2002-328302 A

  However, the thing of patent document 1 is the structure which changes magnification by moving a some prism. Therefore, it is necessary to secure a movement space for the prism in the apparatus in advance, which leads to an increase in the size of the apparatus. In addition, since a precision is required for a mechanism for accurately moving the prism in a straight line, the structure becomes complicated, which increases costs and greatly hinders assembly.

  Next, in Patent Document 2, the aperture is moved with respect to the prism, and the magnification is changed by changing the incident position of the light beam. However, since the optical system forms a primary image, the optical system becomes large. In addition to the movement mechanism, a mechanism for changing the size of the opening diameter is required in order to provide the opening with a brightness adjustment function. As a result, the mechanism becomes complicated and large.

  Since Patent Document 3 is also an optical system that forms a primary image, the optical system becomes large. Further, the magnification is changed by rotating the prism on the image side with the position of the primary image as the rotation center. The image plane also rotates as the optical element rotates.

  The present invention has been made in view of such problems of the prior art, and an object thereof is a variable magnification optical system that is compact and does not require movement of an image sensor arranged on an image plane, and uses the same. To provide electronic equipment.

The variable magnification optical system of the present invention is a variable magnification optical system comprising a stop and one or more optical elements having at least one optical function surface closer to the object side than the stop,
At least one of the optical functional surfaces is a continuous surface,
When a plane defined by a direction vector directed to a distant object and a vector passing through the center of the diaphragm and perpendicular to the diaphragm surface is used as a reference plane, an intersection line formed by the intersection of the reference plane and the optical functional surface The optical functional surface is configured such that the shape is a shape in which at least the radius of curvature continuously changes from one end to the other end,
When the axis perpendicular to the reference plane passing through a point not in contact with the optical function surface in the reference plane is a rotation axis, the optical element is rotated around the rotation axis, and
The image plane is fixed with respect to the stop or moves in a fixed plane.

  In the variable power optical system, at least one of the optical functional surfaces is a reflecting surface.

  The variable magnification optical system includes one or more other optical elements having at least one optical function surface on the image side from the stop, and at least one of the optical function surfaces of the another optical element is continuous. The shape of the line of intersection formed by intersecting the reference surface and the optical functional surface of the other optical element is such that the radius of curvature in the cross-sectional direction continuously changes from one end to the other end. The optical functional surface of the another optical element is configured so that

  According to another aspect of the present invention, there is provided an electronic apparatus including the above-described variable-power optical system and an image sensor disposed on the image side.

  Hereinafter, the reason and effect | action which take the said structure in this invention are demonstrated.

  In the variable magnification optical system of the present invention, at least one optical function surface including a reflecting surface and a refracting surface is disposed on the object side of the stop. Then, the optical function surface is rotated around a point away from the optical function surface. With such a configuration, it is possible to change the position of a light beam (flux) that passes (reflects or refracts) the optical functional surface. Thus, zooming is performed. As a result, a compact variable magnification optical system is realized with a small number of optical elements and low cost. Further, since the aperture position is fixed, the aperture mechanism is simplified. Further, since the image plane is fixed with respect to the fixed diaphragm or moves within the fixed plane, it is not necessary to move the image pickup device arranged on the image plane, and the structure relating to the image pickup device is simplified. , More compact.

  This will be described more specifically. FIG. 1 is a schematic diagram showing a configuration of a variable magnification optical system. This variable magnification optical system is an optical system that forms an image of a distant object O on the image plane 3 without forming an intermediate image. Here, a direction vector from the variable magnification optical system toward a distant object (subject) O is a vector A. A direction vector passing through the center of the aperture stop 2 of the optical system and perpendicular to the stop surface is a vector B. Since one plane is defined by the vector A and the vector B, the plane is defined as a reference plane (YZ plane) in the present invention. This reference plane is in the drawing in FIG. This variable magnification optical system is configured to be plane-symmetric with respect to this reference plane.

  The variable magnification optical system includes one or more optical elements 10 having at least one optical function surface on the object side of the stop 2. In the case of FIG. 1, the optical element 10 includes three optical function surfaces 11, 12, and 13 and constitutes one reflecting prism. However, the optical function surface may be one surface or four or more surfaces. In the case of FIG. 1, the optical functional surface 12 is illustrated as a reflective surface, but may not necessarily be a reflective surface and may be a refractive surface. In the case of FIG. 1, the optical function surfaces 11 and 13 are refractive surfaces.

  The variable magnification optical system rotates the optical element 10 about a rotation axis (center axis) S perpendicular to the reference plane. That is, this variable magnification optical system attempts to perform variable magnification by rotation.

  The optical function surface 12 preferably has the following shape. First, it is preferable that the optical function surface 12 is composed of a continuous surface. The continuous surface is, for example, a surface whose shape changes smoothly. Next, it is preferable that the optical function surface 12 is composed of a surface including regions having different curvature radii. This point will be described. An intersection line is formed by the intersection of the reference surface and the optical functional surface. This intersection line is naturally included in the optical function surface 12. The shape of this intersection line is preferably a shape in which at least the radius of curvature (the radius of curvature in the plane of the drawing) continuously changes from one end to the other end. In other words, the optical function surface 12 needs to be configured by a surface including an intersection line having such a shape. In order to continuously change the focal length of the optical system, (1) the position of the axial principal ray 1 that intersects the optical function surface 12 changes with rotation, and (2) the line of intersection It is necessary that the radius of curvature of the optical function surface 12 continuously changes in the direction along the direction. Of course, it is desirable that the radius of curvature in the direction perpendicular to the reference plane also changes continuously in the same manner. The axial principal ray is a ray that passes through the center of the stop 2 and reaches the center of the image plane 3.

  Here, the position of the rotation axis S needs to be a point that is not on the intersection line (a point that does not contact the optical function surface 12 in the reference plane). If it does in this way, the point of the axial principal ray 1 which cross | intersects the optical function surface 12 will change with rotation of the optical element 10. FIG. In particular, when the position of the rotation axis S is set to a position away from the intersection line, the point of the axial principal ray 1 that intersects the optical function surface 12 can be greatly changed. As a result, the zoom ratio can be increased.

  An intersection line is also formed when the reference surface and the optical function surface 11 intersect. An intersection line is also formed when the reference surface and the optical function surface 13 intersect. Of course, the rotation axis S may be located on the line of intersection (may be in contact with the optical function surfaces 11 and 13 other than the optical function surface 12). If the rotation axis S is in or near the prism, the amount of movement of the prism can be reduced when the prism is rotated.

  As described above, a rotationally asymmetric surface can be considered as a surface having a shape in which the radius of curvature continuously changes in one cross section. A typical example is a free-form surface. The free-form surface is defined by the following equation. The Z axis of this defining formula is the axis of the free-form surface.

₆₆
Z = cr ² / [1 + √ {1− (1 + k) c ² r ² }] + ΣC _j X ^m Y ^{n
j = 2}
... (a)
Here, the first term of the equation (a) is a spherical term, and the second term is a free-form surface term.

In the spherical term,
c: curvature of vertex k: conic constant (conical constant)
r = √ (X ² + Y ² )
It is.

The free-form surface term is
₆₆
ΣC _j X ^m Y ^{n
j = 2}
= C ₂ X + C ₃ Y
+ C ₄ X ² + C ₅ XY + C ₆ Y ²
+ C ₇ X ³ + C ₈ X ² Y + C ₉ XY ² + C ₁₀ Y ³
+ C ₁₁ X ⁴ + C ₁₂ X ³ Y + C ₁₃ X ² Y ² + C ₁₄ XY ³ + C ₁₅ Y ⁴
+ C ₁₆ X ⁵ + C ₁₇ X ⁴ Y + C ₁₈ X ³ Y ² + C ₁₉ X ² Y ³ + C ₂₀ XY ⁴
+ C ₂₁ Y ⁵
+ C ₂₂ X ⁶ + C ₂₃ X ⁵ Y + C ₂₄ X ⁴ Y ² + C ₂₅ X ³ Y ³ + C ₂₆ X ² Y ⁴
+ C ₂₇ XY ⁵ + C ₂₈ Y ⁶
+ C ₂₉ X ⁷ + C ₃₀ X ⁶ Y + C ₃₁ X ⁵ Y ² + C ₃₂ X ⁴ Y ³ + C ₃₃ X ³ Y ⁴
+ C ₃₄ X ² Y ⁵ + C ₃₅ XY ⁶ + C ₃₆ Y ⁷
・ ・ ・ ・ ・ ・
However, C _j (j is an integer of 2 or more) is a coefficient.

  In general, the free-form surface does not have a symmetric surface in both the XZ plane and the YZ plane, but by setting all odd-order terms of X to 0, the plane of symmetry is parallel to the YZ plane. Is a free-form surface with only one. Further, by setting all odd-numbered terms of Y to 0, a free-form surface having only one symmetry plane parallel to the XZ plane is obtained.

  Further, another defining formula of the free-form surface which is a surface of the rotationally asymmetric curved surface can be defined by a Zernike polynomial. The shape of this surface is defined by the following formula (b). The Z axis of the defining formula (b) is the axis of the Zernike polynomial. The definition of the rotationally asymmetric surface is defined by polar coordinates of the height of the Z axis with respect to the XY plane, R is the distance from the Z axis in the XY plane, A is the azimuth around the Z axis, and the X axis It is expressed by the rotation angle measured from.

x = R × cos (A)
y = R × sin (A)
Z = D ₂
+ D ₃ Rcos (A) + D ₄ Rsin (A)
+ D ₅ R ² cos (2A) + D ₆ (R ² −1) + D ₇ R ² sin (2A)
+ D ₈ R ³ cos (3A) + D ₉ (3R ³ −2R) cos (A)
+ D ₁₀ (3R ³ -2R) sin (A) + D ₁₁ R ³ sin (3A)
^{_{+ D 12 R 4 cos (4A}} ) + D 13 (4R 4 -3R 2) cos (2A)
+ D ₁₄ (6R ⁴ -6R ² +1) + D ₁₅ (4R ⁴ -3R ² ) sin (2A)
^{_{+ D 16 R 4 sin (4A}} ) + D 17 R 5 cos (5A) + D 18 (5R 5 -4R 3) cos (3A)
+ D ₁₉ (10R ⁵ -12R ³ + 3R) cos (A)
+ D ₂₀ (10R ⁵ -12R ³ + 3R) sin (A)
+ D ₂₁ (5R ⁵ -4R ³ ) sin (3A) + D ₂₂ R ⁵ sin (5A)
^{_{+ D 23 R 6 cos (6A}} ) + D 24 (6R 6 -5R 4) cos (4A)
+ D ₂₅ (15R ⁶ -20R ⁴ + 6R ² ) cos (2A)
+ D ₂₆ (20R ⁶ -30R ⁴ + 12R ² -1)
+ D ₂₇ (15R ⁶ -20R ⁴ + 6R ² ) sin (2A)
+ D ₂₈ (6R ⁶ -5R ⁴ ) sin (4A) + D ₂₉ R ⁶ sin (6A)
... (b)
However, _Dm (m is an integer greater than or equal to 2) is a coefficient. In order to design an optical system symmetrical in the X-axis direction, D ₄ , D ₅ , D ₆ , D ₁₀ , D ₁₁ , D ₁₂ , D ₁₃ , D ₁₄ , D ₂₀ , D ₂₁ , D ₂₂ . Use.

  The above definition formula is shown for illustration of a rotationally asymmetric curved surface, and it goes without saying that the same effect can be obtained for any other definition formula.

  In addition, the following definition formula (c) is mention | raise | lifted as an example of the other definition formula of a free-form surface.

Z = ΣΣC _nm XY
As an example, when k = 7 (seventh order term) is considered, when expanded, it can be expressed by the following expression.

Z = C ₂
+ C ₃ Y + C ₄ | X |
+ C ₅ Y ² + C ₆ Y | X | + C ₇ X ²
+ C ₈ Y ³ + C ₉ Y ² | X | + C ₁₀ YX ² + C ₁₁ | X ³ |
+ C ₁₂ Y ⁴ + C ₁₃ Y ³ | X | + C ₁₄ Y ² X ² + C ₁₅ Y | X ³ | + C ₁₆ X ⁴
+ C ₁₇ Y ⁵ + C ₁₈ Y ⁴ | X | + C ₁₉ Y ³ X ² + C ₂₀ Y ² | X ³ |
+ C ₂₁ YX ⁴ + C ₂₂ | X ⁵ |
+ C ₂₃ Y ⁶ + C ₂₄ Y ⁵ | X | + C ₂₅ Y ⁴ X ² + C ₂₆ Y ³ | X ³ |
+ C ₂₇ Y ² X ⁴ + C ₂₈ Y | X ⁵ | + C ₂₉ X ⁶
+ C ₃₀ Y ⁷ + C ₃₁ Y ⁶ | X | + C ₃₂ Y ⁵ X ² + C ₃₃ Y ⁴ | X ³ |
+ C ₃₄ Y ³ X ⁴ + C ₃₅ Y ² | X ⁵ | + C ₃₆ YX ⁶ + C ₃₇ | X ⁷ |
... (c)
An anamorphic surface or a toric surface can be used as the rotationally asymmetric surface.

  In the present invention, the image plane 3 is fixed with respect to the fixed stop 2 (second embodiment described later) or moves within the fixed plane (first embodiment described later). Is done. In the case where the image plane 3 is fixed or moves within the fixed plane, it is not necessary to move the light receiving portion such as an image pickup device arranged on the image plane, and the structure relating to the light receiving portion is simplified. Therefore, further downsizing is possible.

  Although not shown in FIG. 1, one or more other optical elements having at least one optical function surface may be provided on the image side from the stop 2. Then, at least one optical function surface (hereinafter referred to as an optical function surface X) of the other optical element may be a continuous surface. Then, the shape of the intersection line (hereinafter referred to as the intersection line X) formed by the reference surface and the optical function surface X is such that at least the radius of curvature continuously changes from one end to the other end. In addition, it is desirable that the optical functional surface X be configured. In addition, it is desirable that the radius of curvature in the direction perpendicular to the reference plane also changes continuously.

  As this other optical element, it is desirable to use an optical element having three or more optical functional surfaces, like the optical element 10 disposed on the object side of the diaphragm 2. In particular, it is desirable to use an optical element configured as a reflecting prism. The number of optical function surfaces may be four or more. The optical functional surface may be a reflective surface or a refractive surface.

  In zooming, another optical element may be rotated about the rotation axis S ′. At this time, the zoom ratio can be further increased by rotating the optical element 10 in cooperation with the optical element 10. The rotation axis S ′ is an axis perpendicular to the reference plane. The position of the rotation axis S ′ is a point that is not on the intersection line X.

  Further, the axial principal ray 1 incident on the first surface (the optical function surface 11 in FIG. 1) facing the object O may not be in a fixed state. For example, the variable magnification optical system may be configured such that the axial principal ray 1 moves in parallel according to the change in magnification.

  Further, an optical element on the object side of the diaphragm 2 (hereinafter referred to as an optical element F) and another optical element on the image side of the diaphragm 2 (hereinafter referred to as an optical element R) are rotated to change the magnification. At this time, an optical function surface (hereinafter referred to as an optical function surface F) positioned immediately before the stop and an optical function surface (hereinafter referred to as an optical function surface R) positioned immediately after the stop are used as the stop. On the other hand, it is desirable to configure the imaging optical system so as to rotate in different directions. In such a configuration, the axial principal ray passes through the center of the stop. Therefore, the relative position change of the optical function surface R with respect to the optical function surface F can be greatly increased. As a result, the change in magnification can be increased. However, here, the optical functional surface means a non-planar surface.

  Further, it is desirable that the optical elements F and R have at least one reflecting surface. A space is required for the optical element to rotate. Therefore, the optical elements F and R have at least one reflecting surface, so that the light beam can be folded. That is, it becomes possible to allow the light to pass through the same space a plurality of times. Therefore, the space utilization efficiency increases, leading to a reduction in the size of the optical system. In addition, the occurrence of chromatic aberration and the like can be reduced by having at least one reflecting surface.

  In addition, it is desirable that the optical elements F and R have three or more surfaces. The optical path length in an optical element becomes long because the optical elements F and R have three or more surfaces. Therefore, the change in the optical path length in the optical element accompanying the rotation can be increased. As a result, a larger zooming effect can be obtained with a smaller number of optical elements and a compact volume.

  Moreover, since the optical elements F and R have three or more surfaces, the surfaces of the optical elements can be used as refractive surfaces. If these surfaces have refractive power, it is possible to increase the change in the power arrangement in the optical element accompanying the rotation. Therefore, a larger zooming effect can be obtained with a smaller number of optical elements and a compact volume.

  In addition, it is desirable that the optical elements F and R have at least one rotationally asymmetric surface. When the optical elements F and R rotate, decentration aberrations occur. Therefore, since the optical elements F and R have at least one rotationally asymmetric surface, the occurrence of decentration aberration can be satisfactorily suppressed in the optical elements F and R.

  Further, it is desirable that the rotation angle at the time of zooming of the optical elements F and R satisfies the following conditional expression.

0 ° <θ <120 ° (1)
Where θ is the rotation angle of the optical element.

  By rotating the optical element at a rotation angle satisfying the conditional expression (1), the change in the optical path length and the change in the power arrangement in the optical elements F and R can be increased. Therefore, a larger zooming effect can be obtained with a smaller number of optical elements and a compact volume. If the upper limit of 120 ° of conditional expression (1) is exceeded, the variation in the emission direction of the light beams emitted from the optical elements F and R becomes too large. Therefore, the area of the optical function surface located on the exit side of the optical elements F and R must be increased. As a result, the overall size of the optical system is increased, which is not preferable. Below the lower limit of 0 °, it becomes impossible to select the optical path itself. This makes it impossible to change the optical parameters.

  Alternatively, it is desirable that the following conditional expression (1-1) is satisfied.

5 ° <θ <90 ° (1-1)
If the upper limit of 90 ° to the conditional expression (1-1) is exceeded, the same result as the conditional expression (1) is obtained. If the lower limit of 5 ° is not reached, the zooming effect accompanying rotation is hardly obtained. Alternatively, in order to obtain a zooming effect, the amount of deformation of the shape of the optical function surface must be increased. This is not preferable because it is difficult to suppress the aberration and obtain performance.

  Alternatively, it is more desirable to satisfy the following conditional expression (1-2).

10 ° <θ <60 ° (1-2)
Further, it is desirable that the zoom ratio satisfies the following conditional expression.

1.01 <β <20 (2)
Where β is the zoom ratio.

  By performing zooming at a zoom ratio that satisfies the conditional expression (2), a large zooming effect can be obtained while maintaining performance. If the upper limit of 20 to conditional expression (2) is exceeded, the required rotation angle becomes large. In this case, the variation in the emission direction of the light beam emitted from the optical element F becomes too large. Therefore, the area of the optical function surface located on the exit side of the optical element F must be increased. As a result, the overall size of the optical system is increased, which is not preferable. Alternatively, in order to realize the zoom ratio, the amount of deformation of the shape of the optical function surface must be increased. In this case, it is difficult to obtain performance by suppressing aberration, which is not preferable. If the lower limit of 1.01 is not reached, the zoom ratio becomes small, which is not preferable.

  Alternatively, it is desirable that the following conditional expression (2-1) is satisfied.

1.5 <β <18 (2-1)
Alternatively, it is more desirable to satisfy the following conditional expression (2-2).

1.8 <β <16 (2-2)
Moreover, it is desirable to satisfy the following conditional expressions.

0 <ν _max −ν _min <100 (3)
Where ν _max is the maximum Abbe number of the optical element included in the optical system,
ν _min : the minimum Abbe number of the optical element included in the optical system,
It is.

  By using optical elements (optical element F and optical element R) that satisfy the conditional expression (3), chromatic aberration generated in the optical system can be satisfactorily suppressed with a smaller number of optical elements and a compact volume. If the upper limit of 100 in conditional expression (3) is exceeded, no resource exists. When the lower limit of 0 is exceeded, the optical system is composed of one type of material or a material having an exactly the same Abbe number. In this case, the occurrence of chromatic aberration cannot be satisfactorily suppressed, which is not preferable.

  Alternatively, it is desirable that the following conditional expression (3-1) is satisfied.

5 <ν _max −ν _min <100 (3-1)
If the upper limit of 100 of the conditional expression (3-1) is exceeded, no resource exists. Exceeding the lower limit of 5 is not preferable because the difference in Abbe number of the optical material used is too small and the occurrence of chromatic aberration cannot be suppressed well.

  Alternatively, it is more desirable to satisfy the following conditional expression (3-2).

10 <ν _max −ν _min <100 (3-2)
Further, an electronic apparatus according to the present invention includes the above-described variable magnification optical system and an electronic imaging device arranged on the image side. The above variable magnification optical system is small, compact, and low cost. Therefore, if such a variable magnification optical system is mounted on an electronic device as an imaging optical system, it is possible to reduce the size and cost of these electronic devices. Electronic devices include digital cameras, video cameras, digital video units, personal computers, mobile computers, mobile phones, portable information terminals, electronic endoscopes, and the like.

  In this case, it is preferable that the electronic apparatus includes means for electrically correcting the shape of the image formed by the variable magnification optical system. In the above-described variable magnification optical system, image distortion and chromatic aberration that are rotationally asymmetric and have different shapes depending on the magnification are likely to occur. If such an aberration is to be corrected satisfactorily by the optical system, the number of optical elements increases and the optical system becomes larger. Therefore, the optical system can be made more compact by electrically correcting these aberrations that cannot be corrected by the optical system.

  For the correction, it is desirable to prepare correction parameters that differ for each focal length in the table and prepare different correction parameters for each wavelength region (color).

  According to the variable magnification optical system and the electronic apparatus using the same according to the present invention, at least one optical functional surface including a reflective surface and a refractive surface is disposed on the object side from the stop, and the optical functional surface is separated from the optical functional surface. Rotating around a distant point. Thus, the magnification is changed by changing the position of the optical function surface passing (reflecting or refraction) of the light beam contributing to the image formation through the stop. In addition, since the image plane is fixed or moved in a plane fixed with respect to the stop at the time of zooming, it is not necessary to move the light receiving unit such as an image sensor arranged on the image plane. The structure related to the light receiving part is simplified. As a result, it is possible to provide a compact variable magnification optical system with a small number of optical elements and low cost, and an electronic apparatus using the same.

  Embodiments of the variable power optical system (imaging optical system) of the present invention will be described below with reference to the drawings.

  For example, as shown in the cross-sectional view of FIG. 2, the axial principal ray 1 is changed to the first surface closest to the object side of the optical system (in FIG. 2, the cover glass CG1). The first light beam CG1a) is incident perpendicularly to the first surface CG1a), passes through the center of the stop 2 of the optical system, and reaches the center of the image surface 3. Then, the position where the first object surface (the first surface CG1a of the cover glass CG1 in FIG. 2) of the optical system and the axial principal ray 1 at the wide-angle end intersect is set as the decentered optical surface of the decentered optical system. The origin of The direction along the axial principal ray 1 is the Z-axis direction, and the direction from the object toward the first surface is the Z-axis positive direction. Further, a plane in which the optical axis is bent is a YZ plane, and a direction passing through the origin and orthogonal to the YZ plane is an X-axis direction. And let the direction which goes to the back from the surface of the paper of FIG. 2 be an X-axis positive direction. Furthermore, the X axis, the Z axis, and the axis constituting the right-handed orthogonal coordinate system are defined as the Y axis.

  In Examples 1 and 2 to be described later, each surface (optical function surface) is decentered in the YZ plane, and the only symmetric surface of each rotationally asymmetric free-form surface is the YZ plane.

  For the decentered surface, the amount of decentering from the origin of the optical system to the top position of the surface (X, Y, and Z axis shift amounts X, Y, Z, respectively) and the center axis of the surface ( For free-form surfaces, inclination angles (α, β, γ (°), respectively) about the X-axis, Y-axis, and Z-axis of the above-described (a) Z-axis) are given. In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by first rotating the central axis of the surface and its XYZ orthogonal coordinate system by α counterclockwise around the X axis, and then rotating the rotation. The center axis of the surface is rotated β counterclockwise around the Y axis of the new coordinate system, and the coordinate system rotated once is also rotated β counterclockwise around the Y axis, and then 2 degrees The center axis of the rotated surface is rotated γ clockwise around the Z axis of the new coordinate system.

  Further, among the optical action surfaces (optical function surfaces) constituting the optical system of each embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given. The refractive index and Abbe number of the medium are given according to conventional methods.

  2A to 2C show the variable magnification optical system according to Example 1 of the present invention. Here, each figure is a cross-sectional view along the optical axis (axial principal ray) 1 and shows the arrangement and optical path at the wide-angle end, the intermediate state, and the telephoto end. The lateral aberration diagrams of the optical system of this example at the wide-angle end, the intermediate state, and the telephoto end are shown in FIGS. 3, 4, and 5, respectively. In each aberration diagram, (a) is the lateral aberration in the Y direction of the principal ray through which the X direction field angle is zero and the Y direction field angle is zero, and (b) is the X direction field angle is zero and the Y direction field angle is zero. X-ray lateral aberration of the principal ray passing through zero, (c) X-direction angle of view is zero, Y-direction transverse aberration of principal ray passing through the Y negative maximum angle of view, and (d) is zero X-direction angle of view. , The transverse aberration in the X direction of the principal ray passing through the maximum Y negative field angle, (e) is the maximum field angle in the positive X direction, the lateral aberration in the Y direction of the principal ray passing through the maximum field angle in the negative Y direction, and (f) is X-direction lateral aberration of the principal ray that passes through the maximum field angle in the positive X direction and the maximum field angle in the negative Y direction, and (g) shows the transverse direction in the Y direction of the principal ray that passes through the maximum field angle in the positive X direction and zero in the Y direction. Aberration, (h) is X-direction maximum field angle, Y-direction lateral angle is X-direction lateral aberration of zero, and (i) is main X-direction maximum field angle and Y-positive maximum field angle. In the Y direction Aberration, (j) is X-direction maximum field angle, X-direction lateral aberration of principal ray passing through Y-direction maximum field angle, (k) is X-direction field angle is zero, Y-direction maximum field-angle main The lateral aberration in the Y direction of the light beam, (l), indicates the lateral aberration in the X direction of the principal ray passing through the X field angle of zero and the maximum Y positive field angle.

  The variable magnification optical system of Example 1 includes, in order from the object side, a cover glass CG1, a front group optical element 10, an aperture stop 2, a rear group optical element 20, and a cover glass CG2. . In the figure, 3 is an image plane (imaging plane). The cover glasses CG1 and CG2 are formed in a parallel plate shape. The position of the aperture stop 2 is fixed. The opening diameter is fixed or variable.

  The optical element 10 has an incident surface 11, a reflecting surface 12, a reflecting surface 13, and an exit surface 14 as optical function surfaces. This optical element 10 is an eccentric prism. The axial principal ray 1 incident through the incident surface 11 is internally reflected by the reflecting surface 12, then internally reflected by the reflecting surface 13, refracted by the exit surface 14, and exits from the optical element 10. In the optical element 10, the axial principal ray 1 from the incident surface 11 toward the reflecting surface 12 intersects with the axial principal ray 1 from the reflecting surface 13 toward the exit surface 14 in the optical element 10. That is, the incident surface 11, the reflecting surface 12, the reflecting surface 13, and the exit surface 14 are arranged so that the axial principal rays 1 intersect each other. Here, when viewed from the positive direction of the X-axis, the axial principal ray 1 proceeds to rotate clockwise in the optical element 10.

  The optical element 20 includes an incident surface 21, a reflecting surface 22, a reflecting surface 23, and an exit surface 24 as optical function surfaces. This optical element 20 is also an eccentric prism. The axial principal ray 1 incident through the incident surface 21 is internally reflected by the reflecting surface 22, then internally reflected by the reflecting surface 23, refracted by the exit surface 24, and exits from the optical element 20. The axial principal ray 1 from the incident surface 21 toward the reflecting surface 22 and the axial principal ray 1 from the reflecting surface 23 toward the exit surface 24 intersect in the optical element 20. In other words, the incident surface 21, the reflecting surface 22, the reflecting surface 23, and the exit surface 24 are arranged so that the axial principal rays 1 intersect each other. Here, when viewed from the positive direction of the X-axis, the axial principal ray 1 proceeds to rotate counterclockwise within the optical element 20. This is the opposite of the optical element 10.

  The incident surface 11, the reflecting surface 12, the reflecting surface 13, and the exit surface 14 of the optical element 10 and the incident surface 21, the reflecting surface 22, the reflecting surface 23, and the exit surface 24 of the optical element 20 are all formed in a free-form surface shape. ing. These surfaces have rotationally asymmetric power. These planes are eccentric in the YZ plane.

  In the variable magnification optical system of this embodiment, the axial principal ray 1 emitted from the center of the distant object passes through the optical element 10, the center of the aperture stop 2, the optical element 20, and the cover glass CG2, and enters the image plane 3. Form an image of the object. In the variable magnification optical system of this embodiment, the image is only formed on the image plane 3, and no image (intermediate image) is formed therebetween. That is, there is only one image plane.

  In this embodiment, the optical element 10 and the optical element 20 are rotated for zooming. Here, the rotation direction is a direction when viewed from the positive direction of the X axis. The rotation axes are all axes perpendicular to the YZ plane. The optical element 10 rotates clockwise about the rotation axis S1. Accordingly, the optical element 20 rotates clockwise around the central axis S2. Therefore, in the zoom optical system of the present embodiment, it is possible to realize a larger zoom ratio. Here, the rotation axis S <b> 1 is inside the optical element 10. The central axis S2 is inside the optical element 20.

  The zooming is performed from the wide-angle end in FIG. 2A to the telephoto end in FIG. 2C through the intermediate state in FIG. 2B.

  In the variable magnification optical system of this embodiment, the axial principal ray 1 travels in the YZ plane in the optical element 10 and the optical element 20. As described above, the reflecting surfaces are arranged so as to travel in opposite directions. Therefore, even in different zooming states, the decentration aberrations are compensated for each other, so that the aberration can be corrected satisfactorily as a whole. Thus, the arrangement of each surface of the present embodiment is more desirable for aberration correction.

  Here, the shape of the surface of the free-form surface used for defining each optical action surface 11-14, 21-24 of Example 1 is a free-form surface defined by the above-mentioned formula (a). The Z-axis is the axis of the free-form surface. The definition of the power and focal length of the decentered optical system is defined based on FIG. 15 of US Pat. No. 6,124,989 (Japanese Patent Laid-Open No. 2000-66105), for example. The definition of the surface of the free-form surface and the power and focal length of the decentered optical system are the same in the following embodiments.

  Numerical data of this embodiment will be described later. In the numerical data, “FFS” indicates a free-form surface and “REF” indicates a reflecting surface. The refractive index and Abbe number are those of the d line. These are common in the numerical data of the following embodiments.

  In this embodiment, at the time of zooming, the optical element 10 is rotated about the rotation axis S1. The optical element 20 is rotated about the central axis S2. The position of the image plane 3 is decentered (shifted) in the Y direction. The rotation axis S1 and the central axis S2 pass through a plane indicated by the top position of the virtual plane.

  In the amount of eccentricity in the numerical data described later, the surface numbers 4 to 7 represent the amount of eccentricity with respect to the virtual surface of surface number 3. Moreover, regarding the surface numbers 10-13, the eccentricity with respect to the virtual surface of the surface number 9 is represented. At that time, the coordinate system is assumed to be translated from the origin. All other surfaces are shown as eccentric amounts based on the first surface (in FIG. 2, the origin set on the first surface CG1a of the cover glass CG1).

  In the present embodiment, the imaging position differs within the same plane as the magnification is changed. Therefore, an image sensor having a wide imaging range is used as the image sensor. In this way, as shown in FIG. 6, images are formed in different areas within the range of the solid line in the figure. Therefore, even if the imaging positions are different, it is possible to capture an image with the position of the image sensor fixed. In FIG. 6, an image sensor having a long imaging range in the X direction is used. However, as shown in FIG. 7, an image sensor having a long imaging range in the Y direction may be used. Of course, the image sensor may be moved in the Y direction during zooming.

  In this embodiment, the image shape is electrically corrected by using different correction parameters for each wavelength region. Thereby, asymmetric image distortion and color blur can be effectively corrected. As a result, a preferable image shape and image quality can be obtained.

  FIGS. 8A to 8C show a variable magnification optical system according to Example 2 of the present invention. Here, each figure is a cross-sectional view along the optical axis (axial principal ray) 1 and shows the arrangement and optical path at the wide-angle end, the intermediate state, and the telephoto end. The lateral aberration diagrams at the wide-angle end, the intermediate state, and the telephoto end of the optical system of this example are shown in FIGS. 9, 10, and 11, respectively. The meanings of (a) to (l) in each aberration diagram are the same as those in FIGS.

  The variable magnification optical system of Example 2 includes, in order from the object side, a cover glass CG1, a front group optical element 10, an aperture stop 2, a rear group optical element 20, and a cover glass CG2. . In the figure, 3 is an image plane (imaging plane). The cover glasses CG1 and CG2 are formed in a parallel plate shape. The position of the aperture stop 2 is fixed. The opening diameter is fixed or variable.

  The optical element 10 has an incident surface 11, a reflecting surface 12, a reflecting surface 13, and an exit surface 14 as optical function surfaces. This optical element 10 is an eccentric prism. The axial principal ray 1 incident through the incident surface 11 is internally reflected by the reflecting surface 12, then internally reflected by the reflecting surface 13, refracted by the exit surface 14, and exits from the optical element 10. In the optical element 10, the axial principal ray 1 from the incident surface 11 toward the reflecting surface 12 intersects with the axial principal ray 1 from the reflecting surface 13 toward the exit surface 14 in the optical element 10. That is, the incident surface 11, the reflecting surface 12, the reflecting surface 13, and the exit surface 14 are arranged so that the axial principal rays 1 intersect each other. Here, when viewed from the positive direction of the X-axis, the axial principal ray 1 proceeds to rotate clockwise in the optical element 10.

  The optical element 20 includes an incident surface 21, a reflecting surface 22, a reflecting surface 23, and an exit surface 24 as optical function surfaces. This optical element 20 is also an eccentric prism. The axial principal ray 1 incident through the incident surface 21 is internally reflected by the reflecting surface 22, then internally reflected by the reflecting surface 23, refracted by the exit surface 24, and exits from the optical element 20. The axial principal ray 1 from the incident surface 21 toward the reflecting surface 22 and the axial principal ray 1 from the reflecting surface 23 toward the exit surface 24 intersect in the optical element 20. In other words, the incident surface 21, the reflecting surface 22, the reflecting surface 23, and the exit surface 24 are arranged so that the axial principal rays 1 intersect each other. Here, when viewed from the positive direction of the X-axis, the axial principal ray 1 proceeds to rotate counterclockwise within the optical element 20. This is the opposite of the optical element 10.

  The incident surface 11, the reflecting surface 12, the reflecting surface 13, and the exit surface 14 of the optical element 10 and the incident surface 21, the reflecting surface 22, the reflecting surface 23, and the exit surface 24 of the optical element 20 are all formed in a free-form surface shape. ing. These surfaces have rotationally asymmetric power. These planes are eccentric in the YZ plane.

  In the variable magnification optical system of this embodiment, the axial principal ray 1 emitted from the center of the distant object passes through the optical element 10, the center of the aperture stop 2, the optical element 20, and the cover glass CG2, and enters the image plane 3. Form an image of the object. In the variable magnification optical system of this embodiment, the image is only formed on the image plane 3, and no image (intermediate image) is formed therebetween. That is, there is only one image plane.

  Also, in this embodiment, the optical element 10 and the optical element 20 are rotated for zooming. Here, the rotation direction is a direction when viewed from the positive direction of the X axis. The rotation axes are all axes perpendicular to the YZ plane. The optical element 10 rotates clockwise about the rotation axis S1. Accordingly, the optical element 20 rotates clockwise around the central axis S2. Therefore, in the zoom optical system of the present embodiment, it is possible to realize a larger zoom ratio. Here, the rotation axis S <b> 1 is inside the optical element 10. The central axis S <b> 2 is outside the optical element 20, but is located in the vicinity of the optical element 20.

  The zooming is performed from the wide-angle end in FIG. 2A to the telephoto end in FIG. 2C through the intermediate state in FIG. 2B.

  In the variable magnification optical system of this embodiment, the axial principal ray 1 travels in the YZ plane in the optical element 10 and the optical element 20. As described above, the reflecting surfaces are arranged so as to travel in opposite directions. Therefore, even in different zooming states, the decentration aberrations are compensated for each other, so that the aberration can be corrected satisfactorily as a whole. Thus, the arrangement of each surface of the present embodiment is more desirable for aberration correction.

  In this embodiment, at the time of zooming, the optical element 10 is rotated about the rotation axis S1. The optical element 20 is rotated about the central axis S2. The rotation axis S1 and the central axis S2 pass through a plane indicated by the top position of the virtual plane.

  In the amount of eccentricity in the numerical data described later, the surface numbers 4 to 7 represent the amount of eccentricity with respect to the virtual surface of surface number 3, and the surface numbers 10 to 13 represent the amount of eccentricity with respect to the virtual surface of surface number 9. In this case, the coordinate system is assumed to be translated from the origin. All other surfaces are shown as eccentric amounts based on the first surface (in FIG. 2, the origin set on the first surface CG1a of the cover glass CG1).

  In this embodiment, the imaging position does not move with zooming.

  In this embodiment, the image shape is electrically corrected by using different correction parameters for each wavelength region. Thereby, asymmetric image distortion and color blur can be effectively corrected. As a result, a preferable image shape and image quality can be obtained.

  The numerical data of Examples 1-2 are shown below.

Example 1
Wide-angle end Intermediate state Telephoto end Entrance pupil diameter: 1.25 to 1.63 to 2.26
Incident half angle of view [X]: 26.6 °-16.1 °-9.5 °
Incident half angle of view [Y]: 20.6 °-12.2 °-7.1 °
Focal length [X]: 3.5 to 6.2 to 10.6
Focal length [Y]: 3.6 to 6.2 to 10.8
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Reflecting surface Object surface ∞ ∞
1 ∞ Eccentricity (1) 1.4950 65.0
2 ∞ Eccentricity (2)
3 ∞ (virtual plane / rotation axis S1) Eccentricity (3)
4 FFS [1] Eccentricity (4) 1.6069 27.0
5 FFS [2] Eccentricity (5) 1.6069 27.0 REF
6 FFS [3] Eccentricity (6) 1.6069 27.0 REF
7 FFS [4] Eccentricity (7)
8 ∞ (diaphragm surface) Eccentricity (8)
9 ∞ (virtual plane / rotation axis S2) Eccentricity (9)
10 FFS [5] Eccentricity (10) 1.5256 56.4
11 FFS [6] Eccentricity (11) 1.5256 56.4 REF
12 FFS [7] Eccentricity (12) 1.5256 56.4 REF
13 FFS [8] Eccentricity (13)
14 ∞ Eccentricity (14) 1.5163 64.1
15 ∞ Eccentricity (15)
Image plane ∞ Eccentricity (16)
FFS [1]
C ₄ 4.1199 × 10 ^-3 C ₆ 1.6579 × 10 ^-2 C ₈ -8.3836 × 10 ^-3
C ₁₀ -6.6784 × 10 ^-3 C ₁₁ -9.7981 × 10 ^-4 C ₁₃ -4.9007 × 10 ^-4
C ₁₅ -6.1790 × 10 ^-4 C ₁₇ -1.3628 × 10 ^-4 C ₁₉ -6.6807 × 10 ^-6
C ₂₁ -9.1886 × 10 ^-5 C ₂₂ -8.0055 × 10 ^-6 C ₂₄ -7.2830 × 10 ^-6
C ₂₆ 1.0665 × 10 ^-5 C ₂₈ -1.2506 × 10 ^-6
FFS [2]
C ₄ 8.0634 × 10 ^-3 C ₆ 4.2472 × 10 ^-2 C ₈ -3.7988 × 10 ^-3
C ₁₀ -6.9592 × 10 ^-3 C ₁₁ -3.8963 × 10 ^-4 C ₁₃ -3.3523 × 10 ^-5
C ₁₅ -1.2394 × 10 ^-4 C ₁₇ 8.2006 × 10 ^-6 C ₁₉ 2.6962 × 10 ^-5
C ₂₁ -3.6475 × 10 ^-5 C ₂₂ 2.1198 × 10 ^-5 C ₂₄ -2.3662 × 10 ^-5
C ₂₆ 9.1054 × 10 ^-6 C ₂₈ 5.2718 × 10 ^-5
FFS [3]
C ₄ -1.8610 × 10 ^-2 C ₆ 3.6558 × 10 ^-2 C ₈ 5.9500 × 10 ^-3
C ₁₀ -1.6255 × 10 ^-4 C ₁₁ -2.6417 × 10 ^-4 C ₁₃ -1.1929 × 10 ^-3
C ₁₅ 1.7306 × 10 ^-5 C ₁₇ 2.0293 × 10 ^-4 C ₁₉ 1.9287 × 10 ^-4
C ₂₁ 5.5 190 × 10 ^-6 C ₂₂ -4.4072 × 10 ^-6 C ₂₄ -3.6117 × 10 ^-5
C ₂₆ -1.7387 × 10 ^-5 C ₂₈ -9.9860 × 10 ^-7
FFS [4]
C ₄ 1.6475 × 10 ^-2 C ₆ 1.2591 × 10 ^-1 C ₈ 1.1965 × 10 ^-2
C ₁₀ 1.4529 × 10 ^-2 C ₁₁ -1.0843 × 10 ^-3 C ₁₃ -2.1214 × 10 ^-3
C ₁₅ -3.2103 × 10 ^-3 C ₁₇ 1.1666 × 10 ^-4 C ₁₉ -7.1671 × 10 ^-4
C ₂₁ -7.9641 × 10 ^-4 C ₂₂ -3.1475 × 10 ^-5 C ₂₄ 4.3413 × 10 ^-5
C ₂₆ -5.4493 × 10 ^-5 C ₂₈ -5.4977 × 10 ^-5
FFS [5]
C ₄ 6.2235 × 10 ^-2 C ₆ -1.2737 × 10 ^-1 C ₈ -2.2386 × 10 ^-2
C ₁₀ -2.9728 × 10 ^-2 C ₁₁ -1.4407 × 10 ^-3 C ₁₃ -6.2840 × 10 ^-3
C ₁₅ 1.5064 × 10 ^-3 C ₁₇ -7.8959 × 10 ^-4 C ₁₉ -1.2080 × 10 ^-3
C ₂₁ 1.2138 × 10 ^-3 C ₂₂ -3.5433 × 10 ^-5 C ₂₄ -1.7885 × 10 ^-4
C ₂₆ -8.9528 × 10 ^-5 C ₂₈ 1.3578 × 10 ^-4
FFS [6]
C ₄ -2.8201 × 10 ^-2 C ₆ -1.0644 × 10 ^-2 C ₈ -1.6319 × 10 ^-3
C ₁₀ -4.0777 × 10 ^-3 C ₁₁ 1.9865 × 10 ^-4 C ₁₃ -1.7651 × 10 ^-4
C ₁₅ -4.6771 × 10 ^-5 C ₁₇ -9.9306 × 10 ^-5 C ₁₉ -4.4615 × 10 ^-5
C ₂₁ 4.8739 × 10 ^-5 C ₂₂ -1.1266 × 10 ^-5 C ₂₄ -3.1473 × 10 ^-5
C ₂₆ 9.9422 × 10 ^-6 C ₂₈ -3.5723 × 10 ^-6
FFS [7]
C ₄ -1.7230 × 10 ^-2 C ₆ -1.2568 × 10 ^-3 C ₈ 8.3942 × 10 ^-3
C ₁₀ -2.2244 × 10 ^-3 C ₁₁ -2.4421 × 10 ^-4 C ₁₃ -1.7785 × 10 ^-3
C ₁₅ -1.0 150 × 10 ^-4 C ₁₇ -4.7562 × 10 ^-4 C ₁₉ 5.2911 × 10 ^-4
C ₂₁ 1.4342 × 10 ^-4 C ₂₂ -7.7146 × 10 ^-5 C ₂₄ 4.8956 × 10 ^-6
C ₂₆ -8.8928 × 10 ^-5 C ₂₈ -1.4534 × 10 ^-5
FFS [8]
C ₄ -5.7194 × 10 ^-3 C ₆ -1.5926 × 10 ^-1 C ₈ 4.0000 × 10 ^-2
C ₁₀ -1.0419 × 10 ^-1 C ₁₁ 3.0000 × 10 ^-3 C ₁₃ 6.4694 × 10 ^-2
C ₁₅ 7.0466 × 10 ^-2 C ₁₇ 3.2443 × 10 ^-3 C ₁₉ -2.1180 × 10 ^-2
C ₂₁ -1.5618 × 10 ^-2 C ₂₂ 1.0000 × 10 ^-3 C ₂₄ -5.5078 × 10 ^-4
C ₂₆ 2.3414 × 10 ^-3 C ₂₈ 1.2251 × 10 ^-3
Eccentric [1]
X 0.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z 0.50
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y -2.63 Z 3.70
α (variable) β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 2.52 Z -3.10
α -1.53 β 0.00 γ 0.00
Eccentric [5]
X 0.00 Y 3.60 Z 2.86
α 37.08 β 0.00 γ 0.00
Eccentric [6]
X 0.00 Y -2.76 Z 2.99
α 96.04 β 0.00 γ 0.00
Eccentric [7]
X 0.00 Y 5.29 Z -1.72
α 90.03 β 0.00 γ 0.00
Eccentric [8]
X 0.00 Y 3.74 Z 4.43
α 95.00 β 0.00 γ 0.00
Eccentric [9]
X 0.00 Y 9.35 Z 4.55
α (variable) β 0.00 γ 0.00
Eccentric [10]
X 0.00 Y -5.18 Z -0.73
α 101.89 β 0.00 γ 0.00
Eccentric [11]
X 0.00 Y -0.24 Z -0.02
α 76.29 β 0.00 γ 0.00
Eccentric [12]
X 0.00 Y -2.79 Z -3.30
α 29.86 β 0.00 γ 0.00
Eccentric [13]
X 0.00 Y -5.13 Z 2.53
α -18.08 β 0.00 γ 0.00
Eccentric [14]
X 0.00 Y 5.74 Z 8.07
α 0.00 β 0.00 γ 0.00
Eccentric [15]
X 0.00 Y 5.74 Z 8.38
α 0.00 β 0.00 γ 0.00
Eccentric [16]
X 0.00 Y (variable) Z 9.00
α 0.00 β 0.00 γ 0.00
(Variable eccentricity)
Wide angle end Intermediate state Telephoto end eccentricity [3] α -8.24 -17.35 -25.59
Eccentric [9] α 5.21 -5.00 -18.08
Eccentric [16] Y 6.34 5.74 6.23.

Example 2
Wide-angle end Intermediate state Telephoto end Entrance pupil diameter: 1.28 to 1.49 to 2.05
Incident half angle of view [X]: 26.6 °-16.1 °-9.5 °
Incident half angle of view [Y]: 20.6 °-12.2 °-7.1 °
Focal length [X]: 3.5 to 6.2 to 10.2
Focal length [Y]: 3.6 to 6.2 to 10.7
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Reflecting surface Object surface ∞ ∞
1 ∞ Eccentricity (1) 1.4950 65.0
2 ∞ Eccentricity (2)
3 ∞ (virtual plane / rotation axis S1) Eccentricity (3)
4 FFS [1] Eccentricity (4) 1.6069 27.0
5 FFS [2] Eccentricity (5) 1.6069 27.0 REF
6 FFS [3] Eccentricity (6) 1.6069 27.0 REF
7 FFS [4] Eccentricity (7)
8 ∞ (diaphragm surface) Eccentricity (8)
9 ∞ (virtual plane / rotation axis S2) Eccentricity (9)
10 FFS [5] Eccentricity (10) 1.5256 56.4
11 FFS [6] Eccentricity (11) 1.5256 56.4 REF
12 FFS [7] Eccentricity (12) 1.5256 56.4 REF
13 FFS [8] Eccentricity (13)
14 ∞ Eccentricity (14) 1.5163 64.1
15 ∞ Eccentricity (15)
Image plane ∞ Eccentricity (16)
FFS [1]
C ₄ 1.3055 × 10 ^-2 C ₆ 1.7158 × 10 ^-2 C ₈ -3.3085 × 10 ^-3
C ₁₀ -1.2693 × 10 ^-3 C ₁₁ -3.3452 × 10 ^-4 C ₁₃ -2.7224 × 10 ^-4
C ₁₅ 3.2997 × 10 ^-5 C ₁₇ -3.1454 × 10 ^-5 C ₁₉ -1.1086 × 10 ^-5
C ₂₁ 7.3638 × 10 ^-6 C ₂₂ -6.8410 × 10 ^-7 C ₂₄ -4.7836 × 10 ^-7
C ₂₆ 5.9583 × 10 ^-7 C ₂₈ 6.0346 × 10 ^-7
FFS [2]
C ₄ 9.0685 × 10 ^-3 C ₆ 4.7493 × 10 ^-2 C ₈ -2.5602 × 10 ^-3
C ₁₀ -4.4964 × 10 ^-3 C ₁₁ -2.9943 × 10 ^-4 C ₁₃ -6.0927 × 10 ^-5
C ₁₅ 3.0623 × 10 ^-4 C ₁₇ 2.4440 × 10 ^-5 C ₁₉ -6.0912 × 10 ^-8
C ₂₁ -2.9859 × 10 ^-5 C ₂₂ 7.0423 × 10 ^-6 C ₂₄ -2.6415 × 10 ^-6
C ₂₆ -3.2025 × 10 ^-6 C ₂₈ 3.3034 × 10 ^-6
FFS [3]
C ₄ -1.2835 × 10 ^-2 C ₆ 2.6766 × 10 ^-2 C ₈ 1.8145 × 10 ^-3
C ₁₀ -1.6486 × 10 ^-4 C ₁₁ -1.7716 × 10 ^-5 C ₁₃ -2.3532 × 10 ^-4
C ₁₅ 5.3085 × 10 ^-6 C ₁₇ 6.3578 × 10 ^-6 C ₁₉ 2.1391 × 10 ^-5
C ₂₁ 1.1118 × 10 ^-6 C ₂₂ 9.5 390 × 10 ^-6 C ₂₄ -1.4798 × 10 ^-6
C ₂₆ -1.1533 × 10 ^-6 C ₂₈ -4.7863 × 10 ^-8
FFS [4]
C ₄ -1.9619 × 10 ^-2 C ₆ 5.9100 × 10 ^-2 C ₈ 4.5013 × 10 ^-3
C ₁₀ 3.1570 × 10 ^-3 C ₁₁ 7.7245 × 10 ^-4 C ₁₃ -4.5883 × 10 ^-4
C ₁₅ -4.0660 × 10 ^-4 C ₁₇ -4.6753 × 10 ^-5 C ₁₉ 1.4733 × 10 ^-5
C ₂₁ 5.9345 × 10 ^-5 C ₂₂ 2.4486 × 10 ^-7 C ₂₄ -7.0868 × 10 ^-6
C ₂₆ 1.6459 × 10 ^-5 C ₂₈ 9.1560 × 10 ^-6
FFS [5]
C ₄ 4.2989 × 10 ^-2 C ₆ -3.3188 × 10 ^-2 C ₈ -5.4964 × 10 ^-3
C ₁₀ -9.1914 × 10 ^-3 C ₁₁ 1.0796 × 10 ^-3 C ₁₃ -3.6182 × 10 ^-4
C ₁₅ 3.5713 × 10 ^-4 C ₁₇ -1.2943 × 10 ^-4 C ₁₉ -3.2968 × 10 ^-4
C ₂₁ -2.0586 × 10 ^-5 C ₂₂ -3.8154 × 10 ^-5 C ₂₄ -3.8740 × 10 ^-5
C ₂₆ -4.8478 × 10 ^-5 C ₂₈ -2.1636 × 10 ^-5
FFS [6]
C ₄ -2.0836 × 10 ^-2 C ₆ 2.7763 × 10 ^-3 C ₈ -1.1247 × 10 ^-3
C ₁₀ -1.7864 × 10 ^-3 C ₁₁ 1.5683 × 10 ^-4 C ₁₃ 1.5867 × 10 ^-4
C ₁₅ -1.2701 × 10 ^-4 C ₁₇ -3.8900 × 10 ^-5 C ₁₉ -6.8193 × 10 ^-6
C ₂₁ 6.1266 × 10 ^-5 C ₂₂ -6.6793 × 10 ^-6 C ₂₄ -2.2776 × 10 ^-5
C ₂₆ -1.1595 × 10 ^-5 C ₂₈ -7.1054 × 10 ^-6
FFS [7]
C ₄ -1.3581 × 10 ^-2 C ₆ 1.9321 × 10 ^-2 C ₈ 5.5282 × 10 ^-3
C ₁₀ -3.1081 × 10 ^-4 C ₁₁ 3.6371 × 10 ^-5 C ₁₃ -5.6046 × 10 ^-4
C ₁₅ -7.8799 × 10 ^-5 C ₁₇ -8.2839 × 10 ^-5 C ₁₉ 2.3033 × 10 ^-5
C ₂₁ 4.4212 × 10 ^-5 C ₂₂ -5.5188 × 10 ^-5 C ₂₄ -3.8246 × 10 ^-5
C ₂₆ -3.3481 × 10 ^-5 C ₂₈ -1.7515 × 10 ^-5
FFS [8]
C ₄ -1.0000 × 10 ^-2 C ₆ -2.7063 × 10 ^-1 C ₈ -3.4215 × 10 ^-2
C ₁₀ -4.7806 × 10 ^-2 C ₁₁ -1.0852 × 10 ^-3 C ₁₃ 6.6446 × 10 ^-2
C ₁₅ 7.1896 × 10 ^-2 C ₁₇ 4.4063 × 10 ^-3 C ₁₉ -1.9200 × 10 ^-2
C ₂₁ -1.8416 × 10 ^-2 C ₂₂ 1.0000 × 10 ^-3 C ₂₄ -7.4672 × 10 ^-4
C ₂₆ 2.1747 × 10 ^-3 C ₂₈ 1.5095 × 10 ^-3
Eccentric [1]
X 0.00 Y 0.00 Z 0.00
α 0.00 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z 0.50
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y -3.59 Z 7.95
α (variable) β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 1.77 Z -6.07
α -3.67 β 0.00 γ 0.00
Eccentric [5]
X 0.00 Y 4.48 Z 3.79
α 37.88 β 0.00 γ 0.00
Eccentric [6]
X 0.00 Y -5.33 Z 2.56
α 91.28 β 0.00 γ 0.00
Eccentric [7]
X 0.00 Y 6.75 Z -2.44
α 88.85 β 0.00 γ 0.00
Eccentric [8]
X 0.00 Y 5.37 Z 10.01
α 95.00 β 0.00 γ 0.00
Eccentric [9]
X 0.00 Y 10.85 Z 13.20
α (variable) β 0.00 γ 0.00
Eccentric [10]
X 0.00 Y -5.30 Z -1.66
α 111.37 β 0.00 γ 0.00
Eccentric [11]
X 0.00 Y -0.30 Z -2.49
α 85.22 β 0.00 γ 0.00
Eccentric [12]
X 0.00 Y -3.88 Z -5.57
α 39.37 β 0.00 γ 0.00
Eccentric [13]
X 0.00 Y -4.11 Z 1.53
α -4.78 β 0.00 γ 0.00
Eccentric [14]
X 0.00 Y 8.39 Z 14.54
α 0.00 β 0.00 γ 0.00
Eccentric [15]
X 0.00 Y 8.39 Z 14.84
α 0.00 β 0.00 γ 0.00
Eccentric [16]
X 0.00 Y 8.39 Z 15.47
α 0.00 β 0.00 γ 0.00
(Variable eccentricity)
Wide angle end Intermediate state Telephoto end eccentricity [3] α -17.24 -26.85 -40.46
Eccentric [9] α -9.26 -28.58 -42.09.

  The values of conditional expressions (1) to (3) in Examples 1 and 2 are shown below.

Conditional expression (1) Conditional expression (2) Conditional expression (3)
Prism 10 Prism 20 X direction Y direction Example 1 17.4 ° 23.3 ° 3.0 3.0 29.4
Example 2 23.2 ° 32.8 2.9 3.0 29.4.

  In the above embodiments, one optical element (eccentric prism) is arranged before and after the stop, but a plurality of optical elements (eccentric prisms) may be arranged on either one or both. Further, an element other than a prism, such as a mirror, may be disposed as the optical element. When the optical element is a decentered prism, the decentered prism is not limited to a decentered prism having two internal reflections as shown in FIGS. For example, various decentered prisms having one or more internal reflections can be used.

  Examples of decentered prisms that can be used as optical elements are shown below. In any case, description will be made assuming that forward ray tracing is performed. That is, the decentering prism P is described as a prism that forms an image of an object located far away on the image plane 136 through the pupil 131. However, these decentered prisms P can also be used as decentered prisms P in which light enters from the image plane 136 side and forms an image on the pupil 131 side.

  In the case of FIG. 12, the decentered prism P includes a first surface 132, a second surface 133, a third surface 133, and a fourth surface 135. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light incident on the decentered prism P is internally reflected by the second surface 133 and internally reflected by the third surface 134 so as to form a Z-shaped optical path. Further, this light enters the fourth surface 135 and is refracted to form an image on the image surface 36.

  In the case of FIG. 13, the decentered prism P includes a first surface 132, a second surface 133, a third surface 134, and a fourth surface 135. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light incident on the decentered prism P is internally reflected by the second surface 133, is incident on the third surface 134, is totally reflected, is incident on the fourth surface 135, and is internally reflected. Further, the light again enters the third surface 134 and is refracted, and forms an image on the image surface 36.

  In the case of FIG. 14, the decentered prism P includes a first surface 132, a second surface 133, a third surface 134, and a fourth surface 135. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light that has entered the eccentric prism P is internally reflected by the second surface 133, is incident on the third surface 134, is internally reflected, and is incident again on the second surface 133 and is internally reflected. Further, this light enters the fourth surface 135 and is refracted to form an image on the image surface 36.

  In the case of FIG. 15, the decentered prism P includes a first surface 132, a second surface 133, a third surface 134, and a fourth surface 135. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light incident on the decentered prism P is internally reflected by the second surface 133 and incident on the third surface 134 and internally reflected. Subsequently, this light is incident again on the second surface 133 and internally reflected, and is incident on the fourth surface 135 and internally reflected. Further, this light is incident again on the second surface 133 and is refracted, and forms an image on the image surface 36.

  In the case of FIG. 16, the decentered prism P includes a first surface 132, a second surface 133, and a third surface 134. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light that has entered the decentered prism P is internally reflected by the second surface 133, is incident again on the first surface 132, and is then totally reflected. Subsequently, this light is internally reflected by the third surface 134, enters the first surface 132 three times, and is totally reflected. Further, the light is incident again on the third surface 134 and is refracted, and forms an image on the image surface 36.

  In the case of FIG. 17, the decentered prism P includes a first surface 132, a second surface 133, and a third surface 134. The light incident through the entrance pupil 131 is refracted by the first surface 132 and enters the eccentric prism P. The light that has entered the decentered prism P is internally reflected by the second surface 133, is incident again on the first surface 132, and is then totally reflected. Subsequently, this light is internally reflected by the third surface 134, enters the first surface 132 three times, and is totally reflected. Further, this light again enters the third surface 134 and is internally reflected, and then enters the first surface 132 four times and is refracted, and forms an image on the image surface 36.

  Furthermore, like the eccentric prism 20 of FIG. 18 to be described later, it may be composed of the first surface 21 to the fourth surface 24 and reflect three times within the prism. Alternatively, like the decentered prism 20 of FIG. 19 to be described later, the second surface 22 includes the first surface 21 to the third surface 23, and the second surface 22 reflects twice within the prism that serves as both the total reflection surface and the exit surface. It may be a thing. Alternatively, like the decentered prism 20 in FIG. 20 described later, the first surface 21 is composed of the first surface 21 to the third surface 23. The first surface 21 serves as both the incident surface and the total reflection surface, and reflects twice in the prism. You may do. These may be used as an optical element (eccentric prism) in the front group or an optical element (eccentric prism) in the rear group.

  FIGS. 18 to 21 below show examples of the variable magnification optical system of the present invention, which is a combination of optical elements (decentered prisms) different from those in the first and second embodiments. However, numerical data is omitted. Further, the eccentric prism is simply referred to as a prism.

  In the case of FIG. 18, the prism 10 is the same as in FIGS. The prism 20 includes a first surface 21 to a fourth surface 24 as optical function surfaces. The first surface 21 is a combined surface that serves both as an incident surface and a second reflecting surface, the second surface 22 is a first reflecting surface, the third surface 23 is a third reflecting surface, and the fourth surface 24 is an exit surface. The light that has passed through the prism 10 and the diaphragm 2 passes through the incident surface 21, is reflected by the first reflecting surface 22, and is then totally reflected by the first surface 21. Subsequently, this light is internally reflected by the third reflecting surface 23, passes through the exit surface 24, and forms an image on the image surface 3. In the prism 20, light rays are internally reflected so as to form an M-shaped optical path in the prism.

  In the case of FIG. 19, the prism 10 has a first surface 11 to a third surface 13 as optical function surfaces. The first surface 11 is an incident surface, the second surface 12 is a reflecting surface, and the third surface 13 is an exit surface. A light beam from the object passes through the incident surface 11, is reflected by the reflecting surface 12, is refracted by the third surface 13, exits from the prism 10, and enters the diaphragm 2. The prism 20 has a first surface 21 to a third surface 23 as optical function surfaces. The first surface 21 is an incident surface, the second surface 22 is a combined surface that serves as both the first reflecting surface and the exit surface, and the third surface 23 is a second reflecting surface. The light beam that has passed through the prism 10 and the diaphragm 2 passes through the incident surface 21, is totally reflected by the first reflecting surface 22, is internally reflected by the second reflecting surface 23, and is then transmitted through the second surface 22 and then the image surface 3. Image on top.

  In the case of FIG. 20, the prism 10 is the same as the prism 10 of FIG. The prism 20 has a first surface 21 to a third surface 23 as optical function surfaces. The first surface 21 is a combined surface that serves both as an incident surface and a second reflecting surface, the second surface 22 is a first reflecting surface, and the third surface 23 is an exit surface. The light beam that has passed through the front group prism 10 and the diaphragm 2 is transmitted through the incident surface 21, reflected by the first reflecting surface 22, then totally reflected by the first surface 21, and then transmitted through the exit surface 23 to pass through the image surface 3. Image on top.

  FIG. 21 is a diagram showing a case where the variable magnification optical system of the present invention is configured. In FIG. 21, one prism 10 is disposed on the front side of the diaphragm 2, and two prisms 20 and 20 ′ are disposed on the rear side of the diaphragm 2. Each of the prisms 10, 20, and 20 'is a prism that performs one reflection within the prism.

  18 to 21 described above, at least the prism 10 is rotated about the central axis S1 perpendicular to the YZ plane for zooming. Desirably, it is preferable to rotate all the prisms in cooperation.

  Moreover, in Examples 1-2, although the resin material is used as a material of an optical element, you may use an organic inorganic composite material instead. The organic-inorganic composite usable in the present invention will be described.

  The organic-inorganic composite is a composite in which an organic component and an inorganic component are mixed and combined at a molecular level or nanoscale. Its form is (1) a structure in which a polymer matrix composed of an organic skeleton and a matrix composed of an inorganic skeleton are entangled with each other and penetrated into each other's matrix. There are those in which inorganic fine particles (so-called nanoparticles) sufficiently smaller than the wavelength of light of the scale are uniformly dispersed, and (3) those having a composite structure of these. Some interaction acts between the organic component and the inorganic component, such as intermolecular forces such as hydrogen bonds, dispersion forces, and Coulomb forces, and attractive forces due to covalent bonds, ionic bonds, and π electron cloud interactions. In the organic-inorganic composite, as described above, the organic component and the inorganic component are mixed at a molecular level or a scale region smaller than the wavelength of light. For this reason, there is almost no influence on light scattering, and a transparent body can be obtained. Further, as derived from the Maxwell equation, the material reflects the optical characteristics of the organic component and the inorganic component. Therefore, various optical characteristics (refractive index, wavelength dispersion) are developed according to the types and abundance ratios of the organic component and the inorganic component. Therefore, various optical characteristics can be obtained by blending organic and inorganic components in any ratio.

Table 1 below shows a composition example of an organic-inorganic composite of acrylate resin (ultraviolet curable) and zirconia (ZrO ₂ ) nanoparticles. Table 2 shows a composition example of an organic-inorganic composite of an acrylate resin and zirconia (ZrO ₂ ) / alumina (Al ₂ O ₃ ) nanoparticles. Table 3 shows a composition example of an organic-inorganic composite of acrylate resin and niobium oxide (Nb ₂ O ₅ ) nanoparticles. Table 4 shows a composition example of an organic-inorganic composite of acrylate resin, zirconium alkoxide, and alumina (Al ₂ O ₃ ) nanoparticles.

Table 1
┌────┬────┬────┬┬────┬────┬────┬─────┐
│ zirconia _{│n d │ν d │n C │n F} │n g │ Notes │
│A content│ │ │ │ │ │ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0 │1.49236 │57.85664 │1.48981 │1.49832 │1.50309 │Acrylic │
│ │ │ │ │ │ │ 100% │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.1 │1.579526 │54.85037 │1.57579 │1.586355 │1.59311 │ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.2 │1.662128 │53.223 │1.657315 │1.669756 │1.678308│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.3 │1.740814│52.27971│1.735014│1.749184│1.759385│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.4 │1.816094│51.71726│1.809379│1.825159│1.836887│ │
├────┼────┼────┼┼────┼────┼────┼─────┤
│ 0.5 │1.888376 │51.3837 │1.880807 │1.898096 │1.911249│ │
└────┴────┴────┴┴────┴────┴────┴─────┘
.

Table 2
┌───┬───┬────┬────┬────┬────┬┬────┬────┐
_{│Al 2 O 3 │ZrO 2 │n d} │ν d │n C │n F │n g │ Remarks │
│ presence rate │ presence rate │ │ │ │ │ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.1 │0.4 │1.831515│53.56672│1.824851│1.840374│1.851956│Acryl│
│ │ │ │ │ │ │ │50% │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.2 │0.3 │1.772832│56.58516│1.767125│1.780783│1.790701│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.3 │0.2 │1.712138│60.97687│1.707449│1.719127│1.727275│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.4 │0.1 │1.649213│67.85669│1.645609│1.655177│1.661429│ │
├───┼───┼────┼────┼────┼────┼┼────┼────┤
│0.2 │0.2 │1.695632│58.32581│1.690903│1.702829│1.774891│ │
└───┴───┴────┴────┴────┴────┴┴────┴────┘
.

Table 3
┌───┬───┬────┬────┬────┬┬────┬────┐
_{│Nb 2 O 5 │Al 2 O 3} │n d │ν d │n C │n F │n g │
│Content│Content│ │ │ │ │ │
├───┼───┼────┼────┼────┼┼────┼────┤
│0.1 │ 0 │1.589861│29.55772│1.584508│1.604464│1.617565│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.2 │ 0 │1.681719 │22.6091 │1.673857 │1.70401 │1.724457│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.3 │ 0 │1.768813 │19.52321 │1.758673 │1.798053 │1.8251 │
├───┼───┼────┼────┼────┼┼────┼────┤
│0.4 │ 0 │1.851815 │17.80818 │1.839583 │1.887415 │1.920475│
├───┼───┼────┼────┼────┼┼────┼────┤
│0.5 │ 0 │1.931253 │16.73291 │1.91708 │1.972734 │2.011334│
└───┴───┴────┴────┴────┴┴────┴────┘
.

Table 4
┌─────┬──────┬────┬────┬┬────┬────┐
│Al ₂ O ₃ (film) │ zirconia A _{│n d │ν d │n C │n F} │
│Content │Lucoxide │ │ │ │ │
├─────┼──────┼────┼────┼┼────┼────┤
│ 0 │ 0.3 │1.533113│58.39837│1.530205│1.539334│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.1 │ 0.27 │1.54737 │62.10192│1.544525│1.553339│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.2 │ 0.24 │1.561498│66.01481│1.558713│1.567219│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.3 │ 0.21 │1.575498│70.15415│1.572774│1.580977│
├─────┼──────┼────┼────┼┼────┼────┤
│ 0.4 │ 0.18 │1.589376│74.53905│1.586709│1.594616│
└─────┴──────┴────┴────┴┴────┴────┘
.

  Now, an electronic apparatus provided with the variable magnification optical system of the present invention as described above will be described. A photographing unit is used for this electronic device. In this photographing unit, an object image is formed by the variable magnification optical system, and the image is picked up by an image sensor such as a CCD or a silver salt film. This imaging unit can also be used as an optical device using a small imaging device, for example, an imaging optical system of an endoscope. The imaging unit can also be used as an observation device for observing an object image through an eyepiece, particularly as an objective optical system of a camera finder. Of course, this imaging unit can also be used as an imaging optical system for a camera.

  Electronic devices include digital cameras, video cameras, digital video units, personal computers that are examples of information processing devices, mobile computers, telephones, especially mobile phones that are convenient to carry, portable information terminals, and electronic endoscopes. is there. The embodiment is illustrated below.

  22 to 24 are conceptual diagrams of configurations in which the optical system of the present invention is incorporated in the objective optical system of the finder portion of the electronic camera. 22 is a front perspective view showing the appearance of the electronic camera 40, FIG. 23 is a rear perspective view thereof, and FIG. 24 is a cross-sectional view showing the configuration of the electronic camera 40.

  In this example, the electronic camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter 45, a flash 46, a liquid crystal display monitor 47, and the like. In such a configuration, when the user presses the shutter 45 disposed on the upper part of the camera 40, photographing is performed through the photographing objective optical system 48 in conjunction therewith.

  An object image formed by the photographic objective optical system 48 is formed on the imaging surface 50 of the CCD 49 via a filter 51 such as a low-pass filter or an infrared cut filter. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 52. In addition, the processing means 52 is provided with a memory or the like, and can record a captured electronic image. This memory may be provided separately from the processing means 52, or may be configured to perform recording and writing electronically using a floppy (registered trademark) disk or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a cover lens 54, a front group prism 10, an aperture stop 2, a rear group prism 20, and a focus lens 66. Here, the optical system according to the present invention is used for the cover lens 54 or the optical system from the first prism 10 to the second prism 20.

  Further, the cover lens 54 used as a cover member is a lens having negative power, and has an increased angle of view. Further, a focusing lens 66 is disposed behind the rear group prism 20. The focus lens 66 can be adjusted in position in the front-rear direction of the optical axis, and is used for adjusting the focus of the finder objective optical system 53. The object image formed on the imaging surface 67 by the finder objective optical system 53 is formed on the field frame 57 of the Porro prism 55 that is an image erecting member. The field frame 57 separates the first reflecting surface 56 and the second reflecting surface 58 of the Porro prism 55 and is disposed therebetween. Behind this polyprism 55 is an eyepiece optical system 59 that guides the erect image to the observer eyeball E.

  The camera 40 configured in this way can configure the finder objective optical system 53 that changes magnification in conjunction with the photographic objective optical system 48 with a small number of optical members. Further, high performance and low cost can be realized, and the optical path itself of the objective optical system 53 can be bent. This increases the degree of freedom of arrangement inside the camera, which is advantageous in design.

  In the configuration of FIG. 22, the configuration of the photographic objective optical system 48 is not mentioned, but a refractive coaxial optical system can be used as the photographic objective optical system 48. Alternatively, it is naturally possible to use the variable magnification optical system of the present invention, that is, an optical system having the front group prism 10 and the rear group prism 20.

  Next, FIG. 25 shows a conceptual diagram of a configuration in which the optical system of the present invention is incorporated in the objective optical system 48 of the photographing unit of the electronic camera 40. In this case, an optical system according to the present invention comprising the front group prism 10, the aperture stop 2, and the rear group prism 20 is used for the photographing objective optical system 48 disposed on the photographing optical path 42.

  The object image formed by the photographing objective optical system 48 is formed on the imaging surface 50 of the CCD 49 through a filter 51 such as a low-pass filter or an infrared cut filter. The object image received by the CCD 49 is displayed as an electronic image on a liquid crystal display element (LCD) 60 via the processing means 52. The processing unit 52 also controls the recording unit 61. The recording means 61 is for recording the object image photographed by the CCD 49 as electronic information. The image displayed on the LCD 60 is guided to the observer eyeball E through the eyepiece optical system 59.

  The eyepiece optical system 59 is composed of a decentered prism. In this example, the eyepiece optical system 59 is composed of three surfaces: an incident surface 62, a reflecting surface 63, and a combined reflecting / refracting surface 64. In addition, at least one of the two reflecting surfaces 63 and 64, preferably both surfaces, provides power to the light beam and has a single symmetry plane that corrects decentration aberrations. It consists of a curved surface. The only symmetry plane is formed on substantially the same plane as the only symmetry plane of the plane-symmetric free-form surface included in the prisms 10 and 20 of the photographing objective optical system 48. In addition, the photographing objective optical system 48 may include other lenses (positive lens, negative lens) as components of the prisms 10 and 20 on the object side, between the prisms, or on the image side.

  In the camera 40 configured as described above, the photographing objective optical system 48 can be configured with a small number of optical members, so that high performance and low cost can be realized, and the entire optical system can be arranged on the same plane. Therefore, it is possible to realize a book shape having a thickness in a direction perpendicular to the arrangement plane.

  In this example, a plane parallel plate is disposed as the cover member 65 of the photographing objective optical system 48, but a lens having power may be used as in the previous example.

  Here, without providing the cover member, the surface disposed closest to the object side in the optical system of the present invention can also be used as the cover member.

  Next, FIGS. 26 to 28 are conceptual diagrams showing a configuration in which the optical system of the present invention is built in a personal computer which is an example of an information processing apparatus.

  26 is a front perspective view with the cover of the personal computer 300 opened, FIG. 27 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 28 is a side view of the state of FIG. As shown in FIGS. 26 to 28, the personal computer 300 includes a keyboard 301, information processing means and recording means, a monitor 302, and a photographing optical system 303.

  Here, the keyboard 301 is used for a writer to input information from the outside. Further, the information processing means and recording means are not shown. The monitor 302 is for displaying information to the operator. The monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. The photographing optical system 303 is for photographing an image of the operator himself or a surrounding area. Note that the photographic optical system 303 is built in the upper right of the monitor 302 in the figure, but is not limited to that location. The photographing optical system 303 may be anywhere around the monitor 302 or the keyboard 301, for example.

  The photographing optical system 303 has an objective optical system 100 including a variable magnification optical system according to the present invention and an image pickup element chip 162 that receives an image on a photographing optical path 304. These are built in the personal computer 300.

  Here, an lR cut filter 180 is additionally attached on the imaging element chip 162. That is, the imaging element chip 162 and the lR cut filter 180 are integrally formed as the imaging unit 160. The imaging unit 160 can be attached by being fitted to the rear end of the lens frame 101 of the objective optical system 100 with a single touch. Therefore, it is not necessary to align the center of the objective optical system 100 and the image sensor chip 162 and to adjust the surface interval, and the assembly is simple. A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the lens frame 101.

  The object image received by the image sensor chip 162 is input to the processing unit of the personal computer 300 via the terminal 166 and displayed on the monitor 302 as an electronic image. FIG. A rendered image 305 is shown. Further, this image 305 can be transmitted to the outside through the processing means. Therefore, it can be transmitted to a communication partner at a remote place via the Internet or a telephone. As a result, the image 305 can be displayed on the personal computer of the communication partner.

  Next, as another example of the information processing apparatus, FIG. 29 shows an example in which the optical system of the present invention is incorporated in a telephone, in particular, a mobile phone that is convenient to carry.

  29A is a front view of the mobile phone 400, FIG. 29B is a side view, and FIG. 29C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 29A to 29C, the mobile phone 400 includes a microphone unit 401, a speaker unit 402, an input dial 403, a monitor 404, a photographing optical system 405, an antenna 406, and processing. Means (not shown).

  Here, the microphone unit 401 is for inputting an operator's voice as information. The speaker unit 402 is for outputting the voice of the other party. An input dial 403 is used by an operator to input information. The monitor 404 is for displaying information such as a photographed image of the operator himself or the other party, a telephone number, and the like. The monitor 404 is a liquid crystal display element. The antenna 406 is for transmitting and receiving communication radio waves. The processing means is for processing image information, communication information, input signals, and the like. In the drawing, the arrangement positions of the respective components are not particularly limited to these.

  The photographing optical system 405 includes an objective optical system 100 that is a variable magnification optical system of the present invention, and an image sensor chip 162 that receives an image. Here, the objective optical system 100 uses the optical system of the present invention and is disposed on the photographing optical path 407. These are built in the mobile phone 400.

  Here, an lR cut filter 180 is additionally attached on the imaging element chip 162. That is, the imaging element chip 162 and the lR cut filter 180 are integrally formed as the imaging unit 160. The imaging unit 160 can be attached by being fitted to the rear end of the lens frame 13 of the objective lens 12 with one touch. Therefore, the centering of the objective lens 12 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the lens frame 101.

  The object image received by the imaging element chip 162 is input to the processing means (not shown) via the terminal 166 and displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted.

  Next, FIG. 30 shows a conceptual diagram of a configuration in which the variable magnification optical system according to the present invention is incorporated in the objective optical system 82 of the observation system of the electronic endoscope. In this example, the objective optical system 82 of the observation system uses a variable magnification optical system having the same form as that of the first embodiment.

  As shown in FIG. 30A, this electronic endoscope includes an electronic endoscope 71, a light source device 72 that supplies illumination light, a video processor 73, a monitor 74, a VTR deck 75, and a video. The disk 76, a video printer 77, and a head-mounted image display device (HMD) 78 are configured. Here, the video processor 73 is for performing signal processing corresponding to the electronic endoscope 71. The monitor 74 is for displaying a video signal output from the video processor 73. The VTR deck 75 and the video disc 76 are connected to the video processor 73 and are used for recording video signals and the like. The video printer 77 is for printing out a video signal as a video.

  The distal end portion 80 of the insertion portion 79 of the electronic endoscope 71 and the eyepiece portion 81 thereof are configured as shown in FIG. The light beam illuminated from the light source device 72 passes through the light guide fiber bundle 88 and illuminates the observation site by the illumination objective optical system 89. Then, light from this observation site is formed as an object image by the observation objective optical system 82 including the variable magnification optical system of the present invention via the cover member 85. This object image is formed on the imaging surface of the CCD 84 through a filter 83 such as a low-pass filter or an infrared cut filter. Further, the object image is converted into a video signal by the CCD 84, and the video signal is directly displayed on the monitor 74 by the video processor 73 shown in FIG.

  The video signal is recorded in the VTR deck 75 and the video disc 76. Alternatively, the image is printed out from the video printer 77 as an image. The video signal is displayed on the image display element of the HMD 78 and displayed to the wearer of the HMD 78. At the same time, the video signal converted by the CCD 84 is displayed on the liquid crystal display element (LCD) 86 of the eyepiece 81 as an electronic image. The display image is guided to the observer eyeball E through the eyepiece optical system 87.

  The endoscope configured as described above can be configured with a small number of optical members, and can realize high performance and low cost. Furthermore, since the objective optical system 80 is arranged in the long axis direction of the endoscope, the above-described effect can be obtained without hindering the diameter reduction.

  The variable magnification optical system of the present invention can also be used as a projection optical system. FIG. 31 shows a conceptual diagram of a presentation system in which a personal computer 90 and a liquid crystal projector 91 are combined. In FIG. 31, the variable magnification optical system according to the present invention is used for the projection optical system 96 of the liquid crystal projector 91. In this example, the optical system according to the present invention including the first prism 10, the aperture stop 2, and the second prism 20 is used for the projection optical system 96.

  In the figure, the image / document data created on the personal computer 90 is branched from the monitor output and output to the processing control unit 98 of the liquid crystal projector 91. In the processing control unit 98 of the liquid crystal projector 91, the input data is processed and output to the liquid crystal panel (LCP) 93. On the liquid crystal panel 93, an image corresponding to the input image data is displayed. The light from the light source 92 is transmitted through the field lens 95 disposed immediately before the liquid crystal panel 93 after the transmission amount is determined by the gradation of the image displayed on the liquid crystal panel 93, and constitutes the optical system of the present invention. The light is projected onto a screen 97 via a projection optical system 96 including a first prism 10, an aperture stop 2, a second prism 20, and a positive lens cover lens 94.

  The projector configured as described above can be configured with a small number of optical members, can achieve high performance and low cost, and can be downsized.

  The variable power optical system of the present invention and the electronic apparatus using the same can be configured as follows, for example.

[1] A variable power optical system comprising a stop and one or more optical elements having at least one optical function surface on the object side of the stop,
At least one of the optical functional surfaces is a continuous surface,
When a plane defined by a direction vector directed to a distant object and a vector passing through the center of the diaphragm and perpendicular to the diaphragm surface is used as a reference plane, an intersection line formed by the intersection of the reference plane and the optical functional surface The optical functional surface is configured such that the shape is a shape in which at least the radius of curvature continuously changes from one end to the other end,
When the axis perpendicular to the reference plane passing through a point not in contact with the optical function surface in the reference plane is a rotation axis, the optical element is rotated around the rotation axis, and
A variable magnification optical system characterized in that an image plane is fixed with respect to the stop or moves within a fixed plane.

    [2] The variable power optical system as described in [1] above, wherein the curvature radius in a direction orthogonal to the reference plane is continuously changed.

    [3] The variable power optical system as set forth in [1], wherein the at least one optical functional surface is a reflecting surface.

    [4] The variable magnification optical system as set forth in [1], wherein the at least one optical functional surface is a refractive surface.

[5] One or more other optical elements having at least one optical function surface are provided on the image side of the stop,
At least one of the optical functional surfaces of the another optical element is a continuous surface;
The shape of the intersection line formed by the intersection of the reference surface and the optical function surface of the other optical element is such that the radius of curvature at least in the cross-sectional direction continuously changes from one end to the other end. 3. The variable magnification optical system according to 1 or 2 above, wherein an optical functional surface of the another optical element is configured.

    [6] The variable power optical system as described in 5 above, wherein the curvature radius in the direction orthogonal to the reference plane is continuously changed.

    [7] At the time of zooming, the other optical element located on the image side from the stop passes through a point that does not contact the optical function surface of the at least one surface in the reference surface and is perpendicular to the reference surface. 7. The variable power optical system as described in 5 or 6 above, wherein the optical system is rotated in cooperation with the optical element closer to the object side than the stop around the axis.

    [8] The variable as described in 7 above, wherein the optical functional surface that is not a plane immediately before the diaphragm and the optical functional surface that is not a plane immediately after the diaphragm rotate in different directions with respect to the diaphragm during zooming. Double optical system.

    [9] The variable magnification optical system according to any one of 1 to 8, wherein the optical element disposed on the object side of the stop has at least one reflecting surface.

    [10] The variable power optical system as described in any one of [1] to [9] above, wherein the optical element disposed on the object side of the stop has three or more surfaces.

    [11] The variable magnification optical system as described in any one of [1] to [10], wherein the optical element disposed on the object side of the stop has at least one rotationally asymmetric surface.

    [12] The variable power optical system as described in any one of 1 to 11 above, wherein a rotation angle at the time of zooming of the optical element disposed on the object side from the stop satisfies the following conditional expression.

0 ° <θ <120 ° (1)
Where θ is the rotation angle of the optical element.

    [13] The zoom optical system according to any one of 1 to 12, wherein the zoom ratio satisfies the following conditional expression:

1.01 <β <20 (2)
Where β is the zoom ratio.

    [14] The zoom optical system according to any one of 1 to 13, wherein the following conditional expression is satisfied.

0 <ν _max −ν _min <100 (3)
Where ν _max is the maximum Abbe number of the optical element included in the optical system,
ν _min : the minimum Abbe number of the optical element included in the optical system,
It is.

    [15] The variable power optical system as set forth in any one of [1] to [14], which has only one imaging plane.

    [16] An electronic apparatus comprising: the variable magnification optical system according to any one of 1 to 15 above; and an imaging device disposed on the image side thereof.

    [17] The electronic apparatus as set forth in [16], further comprising means for electrically correcting the shape of an image formed by the zoom optical system.

    [18] The electronic device as described in 17 above, wherein the correction uses different parameters for each focal length.

    [19] The electronic device as described in 17 or 18 above, wherein the correction uses different parameters for each wavelength region.

It is a schematic diagram which shows the basic composition of the variable magnification optical system of this invention. FIG. 3 is a cross-sectional view showing an arrangement and optical paths at a wide-angle end (a), an intermediate state (b), and a telephoto end (d) of a variable magnification optical system according to Example 1 of the present invention. FIG. 4 is a lateral aberration diagram at the wide-angle end of the optical system according to Example 1. 2 is a lateral aberration diagram in the intermediate state of the optical system of Example 1. FIG. 2 is a lateral aberration diagram at the telephoto end of the optical system of Example 1. FIG. FIG. 3 is a diagram illustrating an imaging region at the time of zooming with respect to the imaging range of the imaging device used in the first embodiment. FIG. 5 is a diagram illustrating an imaging region at the time of zooming with respect to an imaging range of another imaging device used in Example 1. It is sectional drawing which shows the arrangement | positioning and optical path in the wide-angle end (a), intermediate state (b), and telephoto end (d) of the variable magnification optical system which concerns on Example 2 of this invention, respectively. FIG. 6 is a transverse aberration diagram at the wide-angle end of the optical system according to Example 2. 6 is a lateral aberration diagram in the intermediate state of the optical system of Example 2. FIG. 10 is a lateral aberration diagram at the telephoto end of the optical system according to Example 3. FIG. It is a figure which shows one modification of the decentering prism which can be used for the variable magnification optical system of this invention. It is a figure which shows another modification of an eccentric prism. It is a figure which shows another modification of an eccentric prism. It is a figure which shows another modification of an eccentric prism. It is a figure which shows another modification of an eccentric prism. It is a figure which shows another modification of an eccentric prism. It is a figure which shows the example of the variable magnification optical system of this invention which consists of a combination of a prism different from Examples 1-2. It is a figure which shows another example of the variable magnification optical system of this invention which consists of a combination of a prism different from Examples 1-2. It is a figure which shows another example of the variable magnification optical system of this invention which consists of a combination of a prism different from Examples 1-2. It is a figure which shows another example of the variable magnification optical system of this invention which consists of a combination of a prism different from Examples 1-2. It is a front perspective view which shows the external appearance of the electronic camera to which the variable magnification optical system of this invention is applied. It is a back perspective view of the electronic camera of FIG. It is sectional drawing which shows the structure of the electronic camera of FIG. It is a conceptual diagram of another electronic camera to which the variable magnification optical system of the present invention is applied. It is the front perspective view which opened the cover of the personal computer in which the variable magnification optical system of this invention was integrated as an objective optical system. It is sectional drawing of the imaging optical system of a personal computer. It is a side view of the state of FIG. FIG. 2 is a front view (a), a side view (b), and a sectional view (c) of the photographing optical system of a mobile phone in which the variable magnification optical system of the present invention is incorporated as an objective optical system. 1A is a system configuration diagram (a) of an electronic endoscope to which a variable power optical system of the present invention is applied, and FIG. It is a conceptual diagram of the presentation system to which the variable magnification optical system of this invention is applied.

Explanation of symbols

O ... object S, S1, S2 ... rotation axis CG1 ... cover glass CG1a ... cover glass first surface CG1b ... cover glass second surface CG2 ... cover glass E ... observer eyeball 1 ... axial principal ray 2 ... aperture stop 3 ... Image plane 10 ... Optical element (eccentric prism, front group prism)
11: Optical function surface (first surface)
12: Optical function surface (second surface)
13. Optical function surface (third surface)
14: Fourth surface 20: Optical element (eccentric prism, rear group prism)
21 ... 1st surface 22 ... 2nd surface 23 ... 3rd surface 24 ... 4th surface 40 ... Electronic camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter 46 ... Flash 47 ... Liquid crystal display monitor 48 ... Objective optical system 49 for photography ... CCD
DESCRIPTION OF SYMBOLS 50 ... Imaging surface 51 ... Filter 52 ... Processing means 53 ... Finder objective optical system 54 ... Cover lens 55 ... Porro prism 56 ... First reflective surface 57 ... Field frame 58 ... Second reflective surface 59 ... Eyepiece optical system 60 ... Liquid crystal Display element (LCD)
61: Recording means 62 ... Incident surface 63 ... Reflecting surface 64 ... Reflecting and refraction surface 65 ... Cover member 66 ... Focusing lens 67 ... Imaging surface 71 ... Electronic endoscope 72 ... Light source device 73 ... Video processor 74 ... Monitor 75 ... VTR deck 76 ... Video disc 77 ... Video printer 78 ... Head-mounted image display device (HMD)
79 ... Insertion part 80 ... Tip part 81 ... Eyepiece part 82 ... Objective optical system for observation 83 ... Filter 84 ... CCD
85 ... Cover member 86 ... Liquid crystal display element (LCD)
87 ... Eyepiece optical system 88 ... Light guide fiber bundle 90 ... Personal computer 91 ... Liquid crystal projector 92 ... Light source 93 ... LCP (liquid crystal panel)
94 ... Cover lens 95 ... Field lens 96 ... Projection optical system 97 ... Screen 98 ... Processing control unit 100 ... Objective optical system 101 ... Optical frame 102 ... Cover glass 160 ... Imaging unit 162 ... Imaging element chip 166 ... Terminal 180 ... lR cut Filter 300 ... PC 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone unit 402 ... Speaker unit 403 ... Input dial 404 ... Monitor 405 ... Shooting optical system 406 ... Antenna 407 ... light path

Claims (4)

A variable power optical system comprising a stop and one or more optical elements having at least one optical function surface on the object side of the stop,
At least one of the optical functional surfaces is a continuous surface,
When a plane defined by a direction vector directed to a distant object and a vector passing through the center of the diaphragm and perpendicular to the diaphragm surface is used as a reference plane, an intersection line formed by the intersection of the reference plane and the optical functional surface The optical functional surface is configured such that the shape is a shape in which at least the radius of curvature continuously changes from one end to the other end,
When the axis perpendicular to the reference plane passing through a point not in contact with the optical function surface in the reference plane is a rotation axis, the optical element is rotated around the rotation axis, and
A variable magnification optical system characterized in that an image plane is fixed with respect to the stop or moves within a fixed plane. 2. The variable magnification optical system according to claim 1, wherein at least one of the optical functional surfaces is a reflecting surface. One or more other optical elements having at least one optical functional surface on the image side from the stop,
At least one of the optical functional surfaces of the another optical element is a continuous surface;
The shape of the intersecting line formed by the intersection of the reference surface and the optical function surface of the other optical element is such that the radius of curvature at least in the cross-sectional direction continuously changes from one end to the other end. 3. The variable magnification optical system according to claim 1, wherein an optical functional surface of the another optical element is configured. An electronic apparatus comprising: the variable magnification optical system according to any one of claims 1 to 3; and an image pickup device disposed on an image side thereof.

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