JPH09146002A - Optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system by which, an accurate measurement can be carried out and which has a rotationally asymmetrical optical surface which has deviation in center between its outward shape and surface shape. SOLUTION: This optical system has a rotationally asymmetrical surface shape an is arranged slanting to the optical axis, and this system also has at least one optical surface 67 where the center of a surface determined by the outward shape does not meet the center of the surface shape. In this case, at least one rotationally asymmetrical optical surface 67 is provided with one- three indexes 61 indicating reference positions of the surface shape and then the degree of freedom of the position and tilt of measurement data on a design value when the measurement data is fitted to the design value is decreased to less than a half to accurately find the deviation and tilt of a measured body, thereby precisely measuring the surface precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system usable as an eyepiece optical system or an imaging optical system, and more particularly to an optical system having a rotationally asymmetric optical surface.

[0002]

2. Description of the Related Art In recent years, with technological innovation in various fields, new optical systems that have never existed before are required. In order to respond to this, various special optical systems have been developed. Among them, there are rotationally asymmetric optical surfaces, and various designs have been made.

For example, in an optical system such as a head- or face-mounted image display device, which is required to be small and lightweight, a concave mirror arranged at an angle with respect to the optical axis may be used for downsizing. At this time, tilting the concave mirror causes large aberrations such as coma and astigmatism. In order to correct these aberrations, it is conceivable that the surface shape of the concave mirror or other surface is a rotationally asymmetric surface such as an anamorphic surface or a toric surface. However, simply tilting the optical surface causes asymmetrical distortion in the eccentric direction. That is, as shown in FIG. 23, the optical axis 32 direction of the optical system is the Z axis, and the Y axis is the eccentric direction of the optical system.
When the X axis is taken perpendicular to the Y and Z axes, the center 3 of the surface shape
Due to the rotationally asymmetric optical surface 31 having 3, the asymmetric distortion is generated in the Y-axis direction. In order to correct this, as shown in FIG. 24, the rotationally asymmetric optical surface 3 is used.
It can be corrected by arranging the center 33 of the surface shape of No. 1 so as to be displaced from the optical axis 32. Here, the center 33 of the surface shape is the origin of a mathematical expression expressing the surface shape in an anamorphic surface, a toric surface, or the like, and more generally, the surface shape is symmetrical in at least two directions orthogonal to each other in a certain region. It is a point. Further, when the center of the surface shape is displaced with respect to the optical axis as described above, it is general that the center determined by the outer shape of the optical surface does not coincide with the center of the surface shape. The center determined by the outer shape of the optical surface here is the center of the circle when the outer diameter of the optical surface is a circle, and is the intersection of the diagonal lines of the quadrangle if the outer diameter of the optical surface is a quadrangle. is there.

However, if the surface shape center and the center determined by the outer shape of the optical surface are displaced from each other, the following problems occur. When measuring the surface shape after processing the rotationally asymmetric optical surface, a so-called three-dimensional shape measuring machine is often used. For example, as shown in FIG. 25, this measuring machine displays the three-dimensional coordinates of X, Y, Z of thousands to tens of thousands of points on the surface of the optical surface 67 which is the surface to be measured placed on the measuring machine 66. It is measured by the probe 68 and the deviation from the design formula is measured from those coordinates. When the outer shape of the optical surface and the center of the surface shape are coincident with each other, the position of the optical surface 67, which is the object to be measured, can be accurately determined based on the outer shape. Can be compared accurately.

[0005]

However, if the center of the outer shape of the optical surface does not coincide with the center of the surface shape, the optical surface cannot be positioned with reference to the outer shape.
The position of the optical surface with respect to the measuring machine is obtained by estimation from the surface shape measurement result of the optical surface, for example, by a method of fitting the coordinate data of several thousand to tens of thousands which is the measurement result for the surface shape design formula. The fitting of the measurement data is performed by a method such as changing each variable so that the residual by the method of least squares or the like is minimized.

As the fitting variables at this time, in addition to the degree of freedom of the surface shape, as many as six variables including the degree of freedom of three-dimensional position and the degree of freedom of inclination are used for fitting. That is, in general, as schematically shown in FIG. 26, the surface 71 of the design formula and the surface 72 of the measured value are deviated from each other, so that the optical surface 67 as shown by the arrow in FIG.
By changing the position and inclination having six degrees of freedom, the total amount of deviation of the measured values from the design formula, that is, the position and inclination that minimize the residual error are obtained.

In this method, since the position of the object to be measured is approximated to many variables, the exact position of the optical surface is unknown, and the measurement accuracy deteriorates. Particularly, in the case of the reflecting surface, the surface accuracy is particularly severely required, so that the measurement is also required to have high accuracy, and the position of the object to be measured cannot be accurately obtained, which is a big problem.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to enable accurate measurement and to provide rotational asymmetry in which the outer shape of the optical surface and the center of the surface shape do not coincide with each other. It is to provide an optical system having a different optical surface.

[0009]

The optical system according to the first aspect of the present invention for achieving the above object has a rotationally asymmetric surface shape,
In an optical system having at least one optical surface that is arranged to be inclined with respect to the optical axis, and the center of the surface determined by the outer shape and the center of the surface shape do not match, at least one surface of the rotationally asymmetric optical surface, At least one index indicating the reference position of the surface shape is provided.

The optical system according to the second aspect of the present invention has an optical surface having a rotationally asymmetric surface shape, arranged so as to be inclined with respect to the optical axis, and the center of the surface determined by the outer shape does not coincide with the center of the surface shape. In an optical system having at least one surface, at least two indexes indicating the reference position of the surface shape are provided on at least one of the rotationally asymmetric optical surfaces.

An optical system according to a third aspect of the present invention has an optical surface having a rotationally asymmetric surface shape, arranged so as to be inclined with respect to the optical axis, and the center of the surface determined by the outer shape does not coincide with the center of the surface shape. An optical system having at least one surface is characterized in that at least one of the rotationally asymmetric optical surfaces is provided with at least three indexes indicating a reference position of the surface shape.

In the following, the reason why the above configuration is adopted and the operation thereof will be described. As schematically shown in FIG. 1, the first aspect of the present invention has a rotationally asymmetric surface shape, is arranged inclined with respect to the optical axis, and has a center of a surface and a center of the surface shape which are determined by the outer shape. Relates to an optical system having at least one optical surface that does not match, and at least one index 61 indicating the reference position of the surface shape is provided on at least one surface 67 of the rotationally asymmetric optical surface. By doing so, the degree of freedom of the position and inclination of the measured data with respect to the design value when fitting the measured data to the design value becomes, for example, 6 to 3 as indicated by the arrow in FIG. Since the inclination can be accurately obtained, it is possible to measure the surface accuracy with high accuracy.

The second aspect of the present invention, as schematically shown in FIG. 2, has a rotationally asymmetric surface shape, is arranged inclined with respect to the optical axis, and has a center and a surface shape determined by the outer shape. The present invention relates to an optical system having at least one optical surface whose center does not coincide with that of at least two indexes 61 indicating the reference position of the surface shape on at least one surface 67 of the rotationally asymmetric optical surface. . By doing so, the degree of freedom of the position and inclination of the measured data with respect to the design value when fitting the measured data to the design value becomes 1 as indicated by the arrow in FIG. Since it is possible to accurately determine, it becomes possible to measure highly accurate surface accuracy.

The third aspect of the present invention, as schematically shown in FIG. 2, has a rotationally asymmetric surface shape, is arranged inclined with respect to the optical axis, and has a center and a surface shape determined by the outer shape. The present invention relates to an optical system having at least one optical surface whose center does not coincide with that of at least one index 67 indicating a reference position of the surface shape on at least one surface 67 of the rotationally asymmetric optical surface. . By doing so, the degree of freedom of the position and inclination of the measured data with respect to the design value when fitting the measured data to the design value becomes 0, for example, as shown in FIG. Therefore, it is possible to obtain extremely high precision surface accuracy.

It is desirable that such an index is provided as a depression or a protrusion on the optical surface. That is, a molding method is generally used for processing a rotationally asymmetric optical surface. At this time, if the index is a depression or a protrusion on the optical surface, the index can be transferred at the same time as the surface shape.
The index can be provided accurately and easily.

It is desirable that such an index is provided outside the effective area of the optical surface. This is more preferable because the index can be provided without affecting the light rays passing through the optical surface.

Further, in the present invention, at least an optical surface having a rotationally asymmetric surface shape, arranged at an inclination with respect to the optical axis, and having a center of the surface determined by the outer shape and a center of the surface shape not coincident with each other is used. In an optical system having one surface, at least one index indicating the position or inclination of the rotationally asymmetric optical surface may be provided on the side surface of the optical system which is a non-optical surface. This is more preferable because the index can be provided without affecting the light rays passing through the optical surface. Here, the non-optical surface means a surface that does not contribute to transmission or reflection of the optical axis.

In such an optical system, the optical surface having the rotationally asymmetric shape can be used as the reflecting surface. Since the reflective surface is required to have higher precision than the transmissive surface, it is more effective to use the present invention for the reflective surface.

Further, such an optical system can be used together with an image display device in a head- or face-mounted image display device. In the head- or face-mounted image display device,
It is considered to use a decentered concave mirror because an optical system that is smaller in size and whose aberrations are favorably corrected is required.
Therefore, as shown in a side view in FIG. 4, it is more effective to use the optical system 21 according to the present invention together with the image display element 22 in a head- or face-mounted image display device. In addition,
In this figure, the optical system of Example 1 described later is used as the optical system 21.

By adopting the constitution described in each of the embodiments described later, it is possible to observe clearly in a wide angle of view, the brightness of the image is hardly deteriorated, and the image is extremely reduced. Since it is small and lightweight, it is possible to realize an optical system that can be used in an image display device such as a head- or face-mounted type that does not easily cause fatigue.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the optical system according to the present invention is applied to an eyepiece optical system and is used together with an image display element to be applied to a head-mounted image display device as shown in FIG. Will be explained. Example 1 The optical system of this example is a prism having three surfaces, a first surface 3, a second surface 4, and a third surface 5, as shown in the optical path in FIG. 5, and is emitted from the image display element 8. The rays of light are, in turn, the third
The light enters the prism from the surface 5 and is totally reflected by the first surface 3,
After being reflected by the surface 4, the light passes through the first surface 3 and reaches the observer's pupil 1. In the figure, 2 is the visual axis of the observer, 13 is the axis of the optical surface, and 14 is the center of the surface shape.

Although constituent parameters of this embodiment will be described later, the first surface 3 and the second surface 4 are rotationally asymmetric anamorphic surfaces, and as shown in FIG. 6 and FIG. It is provided to clarify the position of the origin of the anamorphic surface, and enables highly accurate measurement of the surface shape.
That is, when fitting the measurement data to the design value of the surface shape, the position of the three indexes 61 at the time of measurement are aligned with the positions of the indexes at the time of designing, so that the degree of freedom of position and inclination is 0, and the measurement of the surface shape is performed. Can be performed with high precision. 6 and 7 are views as seen from the direction of the axis of symmetry, the positions of the indexes are as shown in these figures, and are formed by the depressions on the optical surface.

Example 2 The optical system of this example is the same as that of Example 1, and the constituent parameters are the same as those of Example 1. As shown in FIG. 8, by providing a plate-shaped index 81 composed of two reference surfaces on the side surface of the non-optical surface of the eyepiece optical system, the first surface 3 and the second surface which are rotationally asymmetric optical surfaces. By clarifying the position and inclination of No. 4, it is possible to measure the surface shape with high accuracy. The shape and position of the index are as shown in FIG.

Example 3 The optical system of this example is the same as that of Example 1, and the constituent parameters are the same as those of Example 1. As shown in FIG. 10, by providing a triangular index 82 composed of three reference surfaces on the side surface of the non-optical surface of the eyepiece optical system, the position and inclination of each surface are clarified, and the surface shape is highly accurate. It enables measurement. As shown in FIG. 11, the three reference surfaces are inclined at an angle equal to the amount of eccentricity of each surface 3, 4, 5.

Example 4 The optical system of this example is composed of a concave mirror 11 which is a rear surface mirror and a positive lens 12, as shown in the optical path of FIG. 12, and the light beam emitted from the image display element 8 is , In order, the transmissive surface of the rear surface mirror 11, the reflective surface of the rear surface mirror 11, and the rear surface mirror 11 again.
Of the observer's pupil 1 after passing through the positive lens 12
Reach In this embodiment, the transmission surface and the reflection surface of the concave mirror 11 are rotationally asymmetric optical surfaces, and the same index as that of the first embodiment is provided on each.

Embodiment 5 The optical system of this embodiment is composed of a first reflecting mirror 9 which is a rear surface mirror and a second reflecting mirror 10 which is also a rear surface mirror, as shown in the optical path of FIG. ing. The light rays emitted from the image display element 8 are, in order, the transmission surface of the second reflecting mirror 10,
The reflecting surface of the second reflecting mirror 10, the transmitting surface of the second reflecting mirror 10 again, the transmitting surface of the first reflecting mirror 9, the reflecting surface of the first reflecting mirror 9, and the transmitting surface of the first reflecting mirror 9 again. After passing the plane, it reaches the observer's pupil 1. In this embodiment, the first reflecting mirror 9
The transmissive surface and the reflective surface are rotationally asymmetric optical surfaces, and the same indices as those in the first embodiment are provided on each.

Example 6 The optical system of this example is composed of a positive lens 12 and a concave mirror 11 which is a rear surface mirror, as shown in the optical path of FIG. The light rays emitted from the image display element 8 sequentially pass through the positive lens 12, pass through the transmitting surface of the concave mirror 11, the reflecting surface of the concave mirror 11, and the transmitting surface of the concave mirror 11 again, and then reach the observer's pupil 1. In this embodiment, the transmission surface and the reflection surface of the concave mirror 11 are rotationally asymmetric optical surfaces, and the same index as that of the first embodiment is provided on each.

Example 7 The optical system of this example has a first optical system as shown in FIG.
A light ray emitted from the image display element 8 is a prism made up of the surface 3, the second surface 4, and the third surface 5, which in turn enters the prism from the third surface 5 and is reflected by the second surface 4 before being reflected by the second surface 4. One side 3
To reach the observer's pupil 1. In this embodiment, the first surface 3, the second surface 4 and the third surface 5 of the optical system are rotationally asymmetrical optical surfaces, and the same indices as those in the first embodiment are provided for each.

Example 8 The optical system of this example has a first optical system as shown in FIG.
The light beam emitted from the image display element 8 is the second surface in order of the second surface, the second surface 4, and the fourth surface 6.
The light enters the prism from the surface 4, is reflected by the fourth surface 6, is reflected by the second surface 4, and then is transmitted through the first surface 3 to reach the observer's pupil 1. In this embodiment, the first surface 3 and the fourth surface 6 of the optical system are rotationally asymmetric optical surfaces, and the same indices as those in the first embodiment are provided on each.

Example 9 The optical system of this example has a first optical path as shown in FIG.
The light beam emitted from the image display element 8 is the second surface in order of the second surface, the second surface 4, and the fourth surface 6.
The light enters the prism from the surface 4, is reflected by the fourth surface 6, is reflected by the second surface 4, is reflected again by the fourth surface 6, is reflected again by the second surface 4, and is transmitted through the first surface 3. And reaches the observer's pupil 1. In this embodiment, the second surface 4 and the fourth surface 6 of the optical system are rotationally asymmetric optical surfaces, and the same indices as those in the first embodiment are provided on each.

Example 10 The optical system of this example has a first optical path as shown in FIG.
The light beam emitted from the image display element 8 is the second surface in order of the second surface, the second surface 4, and the fourth surface 6.
The light enters the prism from the surface 4, is reflected by the first surface 3, is reflected by the fourth surface 6, is reflected by the second surface 4, and is transmitted through the first surface 3 to reach the observer's pupil 1. In this embodiment, the first surface 3 and the fourth surface 6 of the optical system are rotationally asymmetric optical surfaces, and the same indices as those in the first embodiment are provided on each.

Example 11 The optical system of this example has a first optical system as shown in FIG.
The light beam emitted from the image display element 8 is a prism having four surfaces, that is, the third surface 5, the second surface 4, the third surface 5, and the fourth surface 6.
In this order, the light enters the prism from the third surface 5, is reflected by the fourth surface 6, is reflected by the second surface 4, and then is transmitted through the first surface 3 to reach the observer's pupil 1. In this embodiment, the second surface 4 of the optical system is a rotationally asymmetric optical surface, and the same index as in the first embodiment is provided.

Example 12 The optical system of this example has a first optical path as shown in FIG.
The light beam emitted from the image display element 8 is a prism having four surfaces, that is, the third surface 5, the second surface 4, the third surface 5, and the fourth surface 6.
In this order, the light enters the prism from the third surface 5, is reflected by the second surface 4, is reflected by the fourth surface 6, is reflected by the second surface 4 again, and then is transmitted through the first surface 3 and the observer's pupil 1 Reach In this embodiment, the second surface 4 of the optical system is a rotationally asymmetric optical surface, and the same index as in the first embodiment is provided.

Example 13 The optical system of this example has a first optical system as shown in FIG.
The light beam emitted from the image display element 8 is a prism having four surfaces, that is, the third surface 5, the second surface 4, the third surface 5, and the fourth surface 6.
In order, the light enters the prism from the third surface 5, is reflected by the fourth surface 6, is reflected by the third surface 5, is reflected by the second surface 4, and is then transmitted through the first surface 3 to the observer's pupil 1. Reach In this embodiment, the second surface 4 of the optical system is a rotationally asymmetric optical surface, and the same index as in the first embodiment is provided.

Example 14 The optical system of this example has a first optical path as shown in FIG.
A light beam emitted from the image display element 8 is a prism having four surfaces, the second surface 4, the fourth surface 6, and the fifth surface 7.
In order, the light enters the prism from the second surface 4, is reflected by the fifth surface 7, is reflected by the second surface 4, is reflected by the fourth surface 6, is reflected by the second surface 4 again, and then is reflected by the first surface 3 To reach the observer's pupil 1. In this embodiment, the second surface 4 and the fourth surface 6 of the optical system are rotationally asymmetric optical surfaces, and the same indices as those in the first embodiment are provided.

The constituent parameters of the first embodiment (the same applies to the second and third embodiments) are shown below. In this configuration parameter, as shown in FIG. 5, the observer's pupil position 1 is the origin of the optical system, and the observer's visual axis 2 is the Z axis. The sign of the Z axis is positive in the direction away from the pupil 1. In addition, the Y axis is taken in the plane of FIG. 5 so that the top of the figure is positive and is orthogonal to the Z axis. Further, the X axis is assumed to be orthogonal to the Y axis and the Z axis, that is, perpendicular to the plane of FIG. The ray tracing is performed by reverse tracing in which the eyeball side of the observer is the object side and the image display element 8 side is the image plane side.

With this configuration parameter, the eccentricity Y,
Z and the amount of inclination θ represent the amount of deviation in the Y direction and the Z direction of the top of the surface from the observer pupil 1 which is the origin of the optical system, and the inclination angle of the central axis of the surface with respect to the Z axis. There is. The tilt angle is positive in the counterclockwise direction.

The shape of the anamorphic surface is defined by the following equation. A straight line passing through the origin of the surface shape and perpendicular to the optical surface is the axis of the anamorphic surface. Where Z is the amount of deviation of the surface shape from the tangent plane, CX is the curvature in the X-axis direction, CY is the curvature in the Y-axis direction, K _x is the conical coefficient in the X-axis direction, K _y is the conical coefficient in the Y-axis direction, and R _n Is an aspherical term rotationally symmetric component, and P _n is an aspherical term rotationally asymmetrical component. In the following configuration parameters, _Rx : radius of curvature in the X-axis direction _Ry : radius of curvature in the Y-axis direction is used, and _Rx = 1 / CX, _Ry = 1 between the curvatures CX and CY. There is a relationship of / CY. In addition, the term relating to the aspherical surface for which no data is given is 0. The refractive index for d-line (wavelength 587.56 nm) is shown.

The constituent parameters of Examples 4 to 14 are omitted. Also, regarding the position of the index,
Although illustration is omitted, since the same index as that of the first embodiment is provided, it is clear from FIGS. 6 and 7.

The constituent parameters are not limited to the following ones, but have a rotationally asymmetric surface shape, are arranged inclined with respect to the optical axis, and have the center of the surface and the surface shape determined by the outer shape. The present invention can be implemented as long as the optical system has at least one optical surface that does not coincide with the center.

Example 1 Surface number Curvature radius Spacing Refractive index Abbe number (amount of eccentricity) (tilt angle) 1 ∞ (pupil) 2 R _y -427.463 1.4922 57.50 (first surface) R _x -57.226 (from pupil position) K _y 20 Y -41.788 θ -7 ° K _x -3.246 Z 26.451 R ₂ 4.032 × 10 ^-7 R ₃ -5.268 × 10 ^-11 P ₂ -0.2351 P ₃ -0.2350 3 R _y -75.807 1.4922 57.50 (2nd surface) R _x -48.700 (from pupil position) (Reflecting surface) K _y -1.5892 Y 32.255 θ 50.18 ° K _x -1.1688 Z 19.157 R ₂ -2.497 × 10 ^-9 R ₃ -1.332 × 10 ^-10 P ₂ 3.7083 P _3- 0.2075 4 R _y -427.463 1.4922 57.50 (1st surface) R _x -57.226 (from pupil position) (Reflecting surface) K _y 20 Y -41.788 θ -7 ° K _x -3.246 Z 26.451 R ₂ 4.032 × 10 ^-7 R ₃ -5.268 × 10 ^-11 P ₂ -0.2351 P ₃ -0.2350 5 ∞ (From pupil position) (3rd surface) Y -34.343 θ -49.02 ° Z 26.451 6 ∞ (From pupil position) (Image display surface) Y- 29.936 θ -45.61 ° Z 39.790.

The above optical system of the present invention can be constructed, for example, as follows. [1] An optical system having a rotationally asymmetric surface shape, arranged at an angle with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape, At least one index indicating the reference position of the surface shape is provided on at least one of the rotationally asymmetric optical surfaces, and the optical system is characterized.

[2] Optical having a rotationally asymmetric surface shape, arranged at an inclination with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. In the system, at least two indexes indicating a reference position of the surface shape are provided on at least one of the rotationally asymmetric optical surfaces, and the optical system.

[3] Optical having a rotationally asymmetric surface shape, arranged at an angle with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. In the system, at least one of the rotationally asymmetric optical surfaces is provided with at least three indexes indicating a reference position of the surface shape.

[4] The above [1], wherein the index is provided as a depression or a protrusion on the optical surface.
The optical system according to any one of items 1 to 3.

[5] The optical system according to any one of [1] to [4], wherein the index is provided outside the effective area of the optical surface.

[6] Optical having a rotationally asymmetric surface shape, arranged at an inclination with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. In the system, at least one index indicating a position or an inclination of the rotationally asymmetric optical surface is provided on a side surface of the optical system which is a non-optical surface.

[7] The optical system as described in any one of [1] to [6] above, wherein in the optical system, the rotationally asymmetrical optical surface is a reflecting surface.

[8] The optical system according to any one of [1] to [7], wherein the optical system is used together with an image display element in a head- or face-mounted image display device. .

[0050]

[9] The optical system has at least two surfaces and includes a first surface that forms a transmission surface and a second surface that forms a reflection surface, and the at least two surfaces are aligned with a visual axis of an observer. The optical element according to the above [8], which is arranged so as to be inclined with respect to one another, and a region between the first surface and the second surface is filled with a medium having a refractive index larger than 1. system.

[10] The above-mentioned [8], wherein the optical system has at least two reflecting mirrors arranged eccentrically to each other, and at least one of them is a concave mirror.
Optical system as described.

[11] The optical system has at least one concave mirror arranged so as to be inclined with respect to an observer's visual axis,
The optical system according to the above [8], wherein at least one optical element having a positive refractive power is arranged between the concave mirror and the image display element.

[12] The optical system has at least three surfaces, and at least a third surface forming a transmitting surface and a second surface forming a reflecting surface in the order in which the light rays emitted from the image display element pass. And the first surface forming a transmission surface, the optical system according to the above [8].

[13] The above-mentioned [1] wherein the first surface of the optical system forms a reflecting surface at the same time as a transmitting surface.
2] The optical system as described above.

[14] A second structure in which the optical system has at least three surfaces and at least a transmission surface and a reflection surface are formed in the order in which the light rays emitted from the image display element pass.
The optical system according to [8] above, which includes a surface, a fourth surface that forms a reflection surface, and a first surface that forms a transmission surface.

[15] In the second surface of the optical system,
The above-mentioned [14], wherein the light ray is transmitted once and reflected twice, and is reflected twice on the fourth surface.
Optical system as described.

[16] A second structure in which the optical system has at least three surfaces and at least a transmission surface and a reflection surface are formed in the order in which the light rays emitted from the image display element pass.
The optical system according to [8] above, which includes a surface, a first surface that forms a transmission surface at the same time as the reflection surface, and a fourth surface that forms a reflection surface.

[17] The optical system has at least four surfaces, and in order of passage of light rays emitted from the image display element, at least a third surface forming a transmission surface and a fourth surface forming a reflection surface. And the second surface that forms the reflective surface and the first surface that forms the transmissive surface, and the optical system according to [8] above.

[18] The above-mentioned [17], wherein the optical system reflects the light beam twice at the second surface.
Optical system as described.

[19] The above-mentioned [1] wherein the third surface of the optical system forms a reflecting surface at the same time as a transmitting surface.
7] The optical system as described above.

[20] A second optical system having at least four surfaces, which performs at least one transmission and two reflections in the order in which the light rays emitted from the image display element pass.
The optical system according to [8] above, which includes a surface, a fifth surface forming a reflecting surface, a fourth surface forming a reflecting surface, and a first surface forming a transmitting surface.

[0062]

As is apparent from the above description, in the present invention, at least one of the rotationally asymmetric optical surfaces in which the outer shape of the optical surface included in the optical system and the center of the surface shape do not coincide with each other.
Since the surface is provided with one or more indexes indicating the reference position of the surface shape, the degree of freedom of the position and inclination of the measured data relative to the design value when fitting the measured data to the design value is reduced to less than half. Further, it becomes possible to accurately obtain the deviation and inclination of the object to be measured, and it is possible to measure the surface accuracy with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a first aspect of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a second aspect of the present invention.

FIG. 3 is a schematic diagram showing a configuration of a third aspect of the present invention.

FIG. 4 is a side view of a head-mounted image display device using the optical system according to the present invention.

FIG. 5 is an optical path diagram of the optical system according to the first embodiment of the present invention.

FIG. 6 is a diagram showing the position of an index provided on the first surface of the first embodiment.

FIG. 7 is a diagram showing the position of an index provided on the second surface of the first embodiment.

FIG. 8 is a diagram showing indexes of Example 2;

FIG. 9 is a diagram showing the shape and position of an index according to the second embodiment.

FIG. 10 is a diagram showing indexes of Example 3;

FIG. 11 is a diagram showing the shape and position of an index according to the third embodiment.

FIG. 12 is an optical path diagram of an optical system according to Example 4 of the present invention.

FIG. 13 is an optical path diagram of an optical system according to Example 5 of the present invention.

FIG. 14 is an optical path diagram of an optical system according to Example 6 of the present invention.

FIG. 15 is an optical path diagram of an optical system according to Example 7 of the present invention.

FIG. 16 is an optical path diagram of an optical system according to Example 8 of the present invention.

FIG. 17 is an optical path diagram of an optical system according to Example 9 of the present invention.

FIG. 18 is an optical path diagram of an optical system according to Example 10 of the present invention.

FIG. 19 is an optical path diagram of an optical system according to Example 11 of the present invention.

FIG. 20 is an optical path diagram of an optical system according to Example 12 of the present invention.

FIG. 21 is an optical path diagram of an optical system according to Example 13 of the present invention.

FIG. 22 is an optical path diagram of an optical system according to Example 14 of the present invention.

FIG. 23 is a diagram showing how distortion is generated by a rotationally asymmetric optical surface that is arranged to be inclined with respect to the optical axis.

FIG. 24 is a diagram showing how distortion is corrected by arranging a rotationally asymmetric optical surface inclined with respect to the optical axis so as to be displaced with respect to the optical axis.

FIG. 25 is a diagram showing how a surface shape is measured using a three-dimensional shape measuring machine.

FIG. 26 is a schematic diagram showing a deviation at the time of fitting between the surface of the design formula and the surface of the measured value.

FIG. 27 is a diagram showing six degrees of freedom of an optical surface.

[Explanation of symbols]

 1 ... Observer pupil position 2 ... Observer visual axis 3 ... First surface of optical system 4 ... Second surface of optical system 5 ... Third surface of optical system 6 ... Fourth surface of optical system 7 ... First surface of optical system 5 surfaces 8 ... Image display element 9 ... First reflecting mirror 10 ... Second reflecting mirror 11 ... Back surface mirror (concave mirror) 12 ... Positive lens 13 ... Anamorphic surface axis 14 ... Surface shape center 21 ... Eyepiece optics System 22 ... Image display element 31 ... Rotationally asymmetric optical surface 32 ... Optical system optical axis 33 ... Center of surface shape 61 ... Index 66 ... Measuring instrument 67 ... Optical surface 68 ... Probe 71 ... Designed surface 72 ... Measured value Surface 81 ... Plate-shaped index 82 ... Triangular index

Claims (3)

[Claims] 1. An optical system having a rotationally asymmetric surface shape, arranged at an angle with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. 2. The optical system according to claim 1, wherein at least one of the rotationally asymmetric optical surfaces is provided with at least one index indicating a reference position of the surface shape. 2. An optical system having a rotationally asymmetric surface shape, arranged at an angle with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. 2. An optical system according to claim 1, wherein at least one of the rotationally asymmetric optical surfaces is provided with at least two indexes indicating a reference position of the surface shape. 3. An optical system having a rotationally asymmetric surface shape, arranged at an angle with respect to the optical axis, and having at least one optical surface in which the center of the surface determined by the outer shape does not coincide with the center of the surface shape. 2. The optical system according to claim 1, wherein at least one of the rotationally asymmetric optical surfaces is provided with at least three indexes indicating the reference position of the surface shape.