JP2003140081A - Hologram combiner optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hologram combiner optical system which permits suppressing of chromatic aberrations without depending upon the monochromaticity of a light source and the wavelength selectability of an HOE. SOLUTION: The hologram combiner optical system arranged with hologram elements for introducing both of the light from a prescribed image display element and the light from the external world to the eyes of a user, in which the ratio of optical power by the diffraction of the hologram elements to the optical power over the entire part of the optical system is below 1. The optical power is allocated to surfaces exclusive of the hologram elements and generally the amount of allocation of the optical power to the hologram elements liable to give rise to the chromatic aberrations is suppressed, by which the chromatic aberrations over the entire part of the hologram combiner optical system is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram combiner optical system in which a hologram element that guides light from a predetermined image display element and light from the outside to the eyes of a user is arranged.

[0002]

2. Description of the Related Art A hologram combiner device includes an image display element such as an LCD and a hologram combiner optical system. By using this hologram combiner device, the user can see the image displayed by the image display element and the scenery of the external world in an overlapping manner.

Holographic combiner optics are generally
A substrate (hologram substrate) made of a parallel plate that transmits light from the outside world, and a hologram that is disposed inside the substrate and that deflects each light from the image display element in a predetermined direction and guides it to the user's eye. Element (HOE; Holographic O
ptical Element). Here, since the HOE governs the traveling direction of light by diffraction, a single wavefront conversion action that requires a plurality of optical surfaces in other optical elements (for example, a refraction optical system and a reflection optical system) is performed. There is an advantage that it can be obtained on the diffraction surface (hologram surface). As a result, the hologram combiner device can be downsized.

However, since the HOE has a large dispersion compared with other optical elements and is liable to cause chromatic aberration, the user may see the color of the displayed image as blurred. There is. In order to suppress this chromatic aberration as much as possible, it is considered that the volume hologram element, which is known to have high wavelength selectivity, is suitable for the hologram combiner device.

[0005]

However, since the light rays from each position of the two-dimensional image have various incident angles, even if the volume hologram element is used, it is high with respect to all the light rays. To maintain diffraction efficiency,
It is difficult to correct the axial chromatic aberration and the off-axis chromatic aberration at the same time. Therefore, it is extremely difficult to express the entire area of the image well. This means that D, which has negative optical power, is
The same is true even if OE (diffractive optical element) is combined.

Therefore, conventionally, in order to display the entire area of the two-dimensional image well, it is necessary to place a restriction on the light source side (light source of the image display element) of the hologram combiner device. This restriction is due to using a laser as the light source,
That is, the monochromaticity of the light source must be increased. However, at present, even if the wavelength width of the light source is suppressed to about ± 1 nm, the chromatic aberration cannot be suppressed sufficiently.

Therefore, an object of the present invention is to provide a hologram combiner optical system capable of suppressing chromatic aberration irrespective of monochromaticity of a light source or wavelength selectivity of HOE.

[0008]

A hologram combiner optical system according to claim 1 is a hologram combiner in which a hologram element for guiding both light from a predetermined image display element and light from the outside to a user's eye is arranged. In the optical system, the ratio of the optical power of the hologram element to the optical power of the entire optical system is less than 1.

In this way, if the optical power is allocated to the surfaces other than the hologram element and the allocation amount of the optical power to the hologram element, which is generally prone to chromatic aberration, is suppressed, the chromatic aberration of the entire hologram combiner optical system is reduced. Is suppressed. The hologram combiner optical system according to claim 2 is the hologram combiner optical system according to claim 1, wherein the ratio of the optical powers is less than 1 and 0.
The above is characterized.

A hologram combiner optical system according to a third aspect is the hologram combiner optical system according to the first or second aspect, wherein the hologram elements are arranged such that the incident angle and the exit angle of the principal ray are substantially equal. It is characterized by being. The hologram combiner optical system according to claim 4 is a hologram combiner optical system in which a hologram element that guides light from a predetermined image display element and light from the outside to a user's eye is arranged. The diffractive surface is formed on a curved surface having a positive optical power.

The hologram combiner optical system according to a fifth aspect is the hologram combiner optical system according to the fourth aspect, wherein the ratio of the optical power of the curved surface to the optical power of the entire hologram element is smaller than 5. Is characterized by. The hologram combiner optical system according to claim 6 is the hologram combiner optical system according to claim 4 or 5, wherein the ratio of the optical power of the hologram element to the optical power of the entire optical system is:
It is characterized by being less than 1.

A hologram combiner optical system according to a seventh aspect is the hologram combiner optical system according to the sixth aspect, characterized in that the ratio of the optical powers is less than 1 and 0 or more. The hologram combiner optical system according to claim 8 is the hologram combiner optical system according to any one of claims 4 to 7, wherein the incident angle and the exit angle of the principal ray are substantially equal to each other. Are arranged.

The hologram combiner optical system according to claim 9 is a hologram combiner optical system in which a hologram element that guides both light from a predetermined image display element and light from the outside to the eyes of the user is arranged. It is characterized in that a refractive optical system and / or a reflective optical system having a positive optical power are arranged. The hologram combiner optical system according to claim 10 is the hologram combiner optical system according to claim 9, wherein the refraction optical system and / or the reflection optical system guides light from the image display element to the hologram element. When it also serves as a system, and when the optical axis of the light from the image display element is included in the horizontal plane, the optical axis of the light guided from the image display element and diffracted by the hologram element is also included in the horizontal plane. It is characterized in that it is configured as follows.

The hologram combiner optical system according to claim 11 is the hologram combiner optical system according to claim 9 or 10, wherein the refractive optical system and / or the reflective optical system comprises a plurality of optical surfaces. The optical power of the first optical surface disposed closest to the image display element is set to be negative.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a configuration and an optical path (only an optical path from the display surface D) of the hologram combiner optical system of the present embodiment. The hologram combiner optical system 11 is arranged between the display surface D of the image display element such as a transmissive LCD and the pupil P of the user's eye.

The exit pupil of the hologram combiner optical system 11 substantially coincides with the pupil P of the user's eye. In order to keep this, the hologram combiner optical system 11 is, for example,
Via a supporting member (not shown) similar to the spectacle frame,
It is attached to the head of the user together with the image display element.

FIG. 1 shows the hologram combiner optical system 11 for the left eye as viewed from above the user's head. Hereinafter, XYZ orthogonal coordinates as shown in the figure will be defined. The origin of this coordinate is the center of the pupil P, and the Z direction (right direction on the paper surface) of this coordinate is the optical axis direction of the user's eye.
The Y direction (upward on the paper surface) is the user's right and left direction, and X
The direction (front and back direction of the page) is the vertical direction (vertical direction) of the user (this hologram combiner optical system 1
1 has a symmetrical shape with respect to the YZ plane. ).

The hologram combiner optical system 11 of this embodiment comprises a hologram substrate 15 on which a hologram element (HOE) 17 is formed, and a correction optical system 18. The hologram substrate 15 is made of a transparent glass or a parallel plate such as a plastic arranged in parallel with the XY plane (that is, arranged opposite to the eye) in order to guide light from the outside to the eye.

Alternatively, at least one surface of the hologram substrate 15 (the surface 15a on the user side or the surface 1 facing it)
5b) is formed into a curved surface having optical power for correcting the visual acuity of the user's eye (hereinafter, a parallel flat plate for simplicity). By the way, the display surface D of the image display element is
The hologram substrate 1 does not hinder the user from observing the outside world and does not interfere with the wearing of the user.
It is arranged in the direction of "-Z" and "+ Y" based on 5, that is, on the left front side of the user.

Incidentally, in the present embodiment, the optical axis of the display surface D is set so that the arrangement position of the image display device is in the lateral direction of the user's eye (in FIG. 1, the left side of the user's left eye). It is made to exist in the horizontal plane (in FIG. 1, in the YZ plane like the optical axis of the eye). Then, the correction optical system 18 directs the light beam from the display surface D having such an arrangement to the surface 1 of the hologram substrate 15.
5a is a catadioptric optical system that leads to an incident surface 15c on the left side of 5a.

The correction optical system 18 of the present embodiment is provided with a positive optical power as a whole, which also serves to reduce the chromatic aberration of the hologram combiner optical system 11. (Details will be described later). For example, the correction optical system 18 is a reflection and refraction optical system having substantially the same shape as a triangular prism, and the refraction surface 18a, the reflection surface 18b, and the refraction surface 18 are arranged in order from the display surface D side.
c is arranged.

The reason that the surface 18b is a reflecting surface is to arrange the display surface D at a position where it does not interfere with the face of the user. Incidentally, although the correction optical system 18 having such a configuration is a single optical element, as shown in FIG. 1, the display surface D is arranged at a position away from the optical axis of the eye.
Is advantageous in that the light from the can be guided to the incident surface 15c of the hologram substrate 15.

Then, the hologram substrate 15 receives a light beam that is incident substantially vertically from the incident surface 15c.
A reflecting surface 15d that reflects in the directions of "-Y" and "-Z" (that is, so as to be obliquely incident on the surface 15a) is formed in the inside of 5. Next, the HOE 17 provided inside the hologram substrate 15 is, for example, a reflective volume hologram element (hereinafter referred to as a reflective volume hologram element).

The HOE 17 is provided inside the hologram substrate 15 at a position facing the eyes of the user. The surface on which the HOE 17 is formed is the surface 15a, 15a.
It is inclined with respect to b, and its inclination angle is 15d.
The light that has exited and traveled inside the hologram substrate 15
It is set so as to be incident on the HOE 17.

Moreover, in this embodiment, the arrangement angle is set so that the incident angle and the exit angle of the principal ray are substantially equal. By setting in this way, HOE1
It is possible to suppress the chromatic aberration occurring in No. 7 to the minimum.
The formation of the HOE 17 on the hologram substrate 15 is performed by, for example, temporarily cutting the hologram substrate 15 along the surface on which the HOE 17 is to be arranged, and sandwiching the HOE 17 between the two to form an adhesive (the refractive index of which is different from that of the hologram substrate 15). They have substantially the same refractive index.

The peak wavelength of the diffraction efficiency of the HOE 17 is substantially the same as the peak wavelength of the light emitted from the display surface D (that is, the light source wavelength). The display surface D
The image displayed in is a color image, and the light source wavelength is R
When there are three types of peak wavelengths corresponding to colors, G color, and B color, three types of diffraction patterns for three types of wavelength bands are formed. That is, a diffraction pattern in which the peak wavelength of the diffraction efficiency substantially matches the wavelength of the R color, and a diffraction pattern in which the peak wavelength of the diffraction efficiency substantially matches the wavelength of the G color,
The diffraction pattern in which the peak wavelength of the diffraction efficiency substantially matches the wavelength of the B color is superimposed.

A predetermined optical power is applied to the hologram combiner optical system 11 including the HOE 17. In the hologram combiner optical system 11 having the above configuration, a light beam emitted from an arbitrary point on the display surface D has a refracting surface 18a and a reflecting surface 18b of the correcting optical system 18.
After sequentially entering the refracting surface 18c, the light enters the hologram substrate 15 from the entrance surface 15c, and reflects on the reflecting surface 15d.
The surfaces 15a and 15b arranged parallel to each other are repeatedly reflected in order, and then diffracted by the HOE 17 and emitted from the surface 15a of the hologram substrate 15 to the outside of the hologram substrate 15, that is, toward the eye of the user.

The emitted light beam is subjected to a predetermined optical power in the hologram combiner optical system 11 and converted into a state close to a parallel light beam. Therefore, from the user's eyes, the display surface D looks farther than it actually is. Here, in the conventional hologram combiner optical system, all of the optical power for making it look like this is given by the diffraction pattern of the HOE 17.

However, in the hologram combiner optical system 11 of this embodiment, the ratio of the optical power of the HOE 17 to the total optical power of the hologram combiner optical system 11 is suppressed to less than 1. That is, of the total optical power of the hologram combiner optical system 11,
The burden on the HOE 17 can be kept small.

And regarding the remaining optical power,
The other optical surface of the hologram combiner optical system 11, for example, the optical surface in the correction optical system 18 is loaded (for the reason that the positive optical power is given to the correction optical system 18 as described above, It is.) In this way HOE1
If the optical power allocated to 7 is suppressed, the diffraction angle (correctly, the difference between the diffraction angle of the principal ray and the diffraction angle of the marginal rays) that should be given to the incident ray can be suppressed, so that many occur in the HOE 17. The chromatic aberration that tends to occur is suppressed.

On the other hand, since the correction optical system 18 is a catadioptric system, even if optical power is applied to it, it is less likely to cause chromatic aberration than the HOE 17.
Therefore, the overall chromatic aberration of the hologram combiner optical system 11 of the present embodiment can be suppressed. Incidentally, in the conventional hologram combiner optical system, the restriction on the monochromaticity of the light source was severe in order to suppress chromatic aberration. But,
In the hologram combiner optical system 11 of the present embodiment, since chromatic aberration is suppressed as described above, if the same performance as the conventional one is obtained, there is a restriction on the monochromaticity of the light source.
Get loose. Further, if a light source having the same wavelength width as the conventional one is used, its performance will be higher than the conventional one.

In the conventional hologram combiner optical system, the wavelength selectivity of the HOE 17 is severely restricted in order to suppress chromatic aberration. However, in the hologram combiner optical system 11 of the present embodiment, chromatic aberration is suppressed, so that if the same performance as the conventional one is obtained, the restriction on the wavelength selectivity of the HOE 17 becomes less strict than the conventional one. Further, if the HOE having the same wavelength selectivity as the conventional one is used, the performance thereof is higher than that of the conventional one.

In the hologram combiner optical system 11 of this embodiment, the hologram combiner optical system 1 is used.
The ratio of the optical power of the HOE 17 to the total optical power of 1 is preferably 0 or more. Because
Comparing the case where the ratio of the optical power is smaller than 0 and the case where the ratio is 0 or more, the latter is the case (even when the same viewing angle is realized by giving the same optical power). This is because the required effective diameter can be kept small. If the effective diameter can be made small, it becomes easy to store the light flux inside the hologram substrate 15 (easy to fold), and as a result,
This is because the hologram substrate 15 can be kept thinner.

[Specific Example of First Embodiment] Tables 1, 2, and 3 show lens data of a hologram combiner optical system which is a specific example of this embodiment. The specifications of this hologram combiner optical system are as follows. That is, the entrance pupil diameter is 3 mm, and the angle of view is ± 6.6 in the X direction.
6 ° ± 5 ° in the Y direction. The apparent distance to the object is -600.000000 mm, and the wavelengths used are 524.44 nm, 514.44 nm, and 504.44 n.
m.

The order of the surface numbers is from the pupil P to the display surface D.
With the direction to. Further, in this hologram combiner optical system, three types of HOE diffraction patterns are prepared in order to display a color image. The above-mentioned wavelength band (525 nm ~
Wavelength bands other than the first wavelength band (near 504 nm) (63
Second wavelength band near 6 nm to 615 nm, 472 nm to 4
The HOE data for the third wavelength band near 51 nm) is shown in Tables 4 and 5.

The operating wavelengths of the HOE data shown in Table 4 are 635.65 nm, 625.65 nm, 615.6.
It is 5 nm, and the used wavelength of HOE data shown in Table 5 is
471.26nm, 461.26nm, 451.265
nm. The refractive index of PMMA used in this example for each wavelength is as follows.

That is, the refractive index for wavelength 471.26 nm is 1.69033, the refractive index for wavelength 461.26 nm is 1.610667, and wavelength 451.26 nm.
Has a refractive index of 1.612429 and a wavelength of 524.44.
nm has a refractive index of 1.620203 and a wavelength of 514.nm.
Refractive index for 44 nm is 1.603167, wavelength 50
The refractive index for 4.44 nm is 1.604378, the refractive index for the wavelength 635.65 nm is 1.593141,
The refractive index for the wavelength of 625.65 nm is 1.59371.
1, the refractive index for wavelength 615.65 nm is 1.594
316.

The PMM used in a specific example described later.
The characteristic of A is the same as the characteristic of PMMA of this specific example. In addition, in the notation of HOE data, "HV
"1" is an object point light source, "HV2" is a reference point light source, "HT
"H" is the thickness of HOE, "HIN" is the refractive index of HOE,
"HDI" is the modulation width of the HOE refractive index, and "HSW" is HO.
The thickness expansion coefficient of E, "HDN" is the refractive index shift of HOE,
“HX1” is the X coordinate of the object point light source, “HY1” is the Y coordinate of the object point light source, “HZ1” is the Z coordinate of the object point light source, and “H”
"X2" is the X coordinate of the reference point light source, "HY2" is the Y coordinate of the reference point light source, "HZ2" is the Z coordinate of the reference point light source, and "HW".
“L” is a light source wavelength (unit: nm) at the time of manufacturing the HOE.

In Tables 4 and 5, "HOR" is the diffraction order, "XDE" is the shift amount in the X direction, and "YDE".
Is the shift amount in the Y direction, and “ZDE” is the shift amount in the Z direction. In each table, the reference numeral in parentheses corresponding to each surface number is the reference numeral given to each surface in the drawing.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5] Incidentally, in this specific example, the optical power of the HOE 17 (focal length 21.0 m) relative to the total optical power of the hologram combiner optical system 11 (focal length 16.0 mm).
The ratio of m) is 0.76.

Further, in this specific example, the incident angle and the outgoing angle of the principal ray with respect to the HOE 17 are 2 and 2, respectively.
They are 9.30000 ° and 29.1320 °. In addition,
Phase coefficients C1, C2, ..., C65 in the HOE data
The phase function of HOE defined by is as shown in the following Expression 3 (the same applies to the embodiments described later).

Incidentally, the general phase function is to express the optical path difference received by the light ray incident on the point designated as the position on the XY plane as the position on the XY plane, and it is expressed by the equation 1 below. There are 65 coefficients of this phase function, which are sequentially set as C1, C2, C3, ..., C65, and the order of the coefficients is represented by an integer j (j = 1, 2, ..., 65) ( The relationship between the integer j and the integers m and n is expressed by Expression (2)) and Expression 3.

The definition of such a phase function is the same for the HOE data in Tables 6, 8, and 10 described later. However, in each table, the description of the phase coefficient of 0 is omitted.

[Equation 1]

[Equation 2]

[Equation 3] The aberration diagrams of this hologram combiner optical system are shown in FIGS. 2, 3, 4, 5, 6, 7, 8, 9 and 1.
It is as 0.

2, 3, and 4 are aberration diagrams for the first wavelength band, FIGS. 5, 6, and 7 are aberration diagrams for the second wavelength band, and FIGS. 8, 9, and 10 are respectively. FIG. 6 is an aberration diagram regarding a third wavelength band. In each figure, “Y-FAN” is the Y direction, “X-FAN” is the X direction, and “FIELD HEIG”.
“HT” indicates an angle of view (angle in X direction, angle in Y direction).

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram showing a configuration and an optical path (only an optical path from the display surface D) of the hologram combiner optical system of the present embodiment. Here, the first
Only differences from the embodiment will be described, and description of other points will be omitted.

The hologram combiner optical system 21 of the present embodiment comprises a hologram substrate 25 on which a HOE 27 is formed,
It comprises correction optical systems 28 and 29. First, unlike the first embodiment, the display surface D of the present embodiment is different from the hologram substrate 1 in the first embodiment.
It is arranged in the direction of "+ Z" and "+ Y" with reference to 5, that is, on the side opposite to the user's eyes.

The optical axis of the display surface D exists in a predetermined plane parallel to the YZ plane, like the optical axis of the user's eye.
It has an inclination angle with the optical axis of the eye. Further, the correction optical systems 28 and 29 are refraction optical systems that guide the light rays from the display surface D having such an arrangement to the incident surface 25c formed on the left side of the hologram substrate 25. The incident surface 25c
On the side close to the display surface D on the hologram substrate 25,
It is formed by cutting out substantially parallel to the display surface D.

Also in the present embodiment, the correction optical systems 28 and 29 are provided with positive optical power as a whole, and thus the function of correcting the chromatic aberration of the hologram combiner optical system 21 is provided. Has been fulfilled. By the way, in the present embodiment, the correction optical systems 28, 2
The surface 29a closest to the display surface D out of 9 has a negative optical power.

By doing so, the telecentricity on the incident side of the hologram combiner optical system 21 can be enhanced. In addition, in a part of the correction optical system 28, 29,
If the surface having the negative optical power is arranged, it becomes easy to correct the aberration of the correction optical system to which the positive optical power should be given as a whole. For example, the correction optical system 28,
Of the 29, the correction optical system 2 arranged on the display surface D side
Reference numeral 9 denotes a meniscus lens in which concave surfaces 29a and 29b toward the display surface D are sequentially arranged, and the other correction optical system 28 is a plano-convex lens in which a convex surface 28a toward the display surface D and a flat surface 28b are sequentially arranged ( The plane 28b is adhered to the entrance surface 25c of the hologram substrate 25 without a gap and has no refraction effect.

In the hologram combiner optical system 21 having the above configuration, the light flux emitted from any point on the display surface D is directed to the surfaces 29a and 29b of the correction optical system 29 and the surfaces 28a and 28b of the correction optical system 28. After incident in order, incident surface 2
5c enters the hologram substrate 25 and faces 25a, 25
b is repeatedly reflected in order, then diffracted by the HOE 27 and emitted outside the hologram substrate 25, that is, toward the user's eye.

As described above, also in the present embodiment, as in the first embodiment, the correcting optical systems 28 and 29 are made to bear a part of the optical power, and the optical power to be given to the HOE 27 by that amount is also burdened. Since it is made small, the chromatic aberration of the entire hologram combiner optical system 21 can be suppressed small. [Specific Example of Second Embodiment] Next, the lens data of the hologram combiner optical system, which is a specific example of this embodiment,
The results are shown in Table 6 and Table 7.

The specifications of this hologram combiner optical system are as follows. That is, the entrance pupil diameter is 3 mm, and the angle of view is ± 6.66 ° in the X direction and ± 5 ° in the Y direction. The apparent distance to the object is -600.000.
000 mm, wavelength used is 524.44 nm, 51
They are 4.44 nm and 504.44 nm. The order of the surface numbers is from the pupil P to the display surface D.

In the notation of HOE data, "H
“V1” is an object point light source, “HV2” is a reference point light source, and “HT
"H" is the thickness of HOE, "HIN" is the refractive index of HOE,
"HDI" is the modulation width of the HOE refractive index, and "HSW" is HO.
The thickness expansion coefficient of E, "HDN" is the refractive index shift of HOE,
“HX1” is the X coordinate of the object point light source, “HY1” is the Y coordinate of the object point light source, “HZ1” is the Z coordinate of the object point light source, and “H”
"X2" is the X coordinate of the reference point light source, "HY2" is the Y coordinate of the reference point light source, "HZ2" is the Z coordinate of the reference point light source, and "HW".
“L” is a light source wavelength (unit: nm) at the time of manufacturing the HOE.

"HOR" is the diffraction order, and "XDE".
Is the shift amount in the X direction, “YDE” is the shift amount in the Y direction,
“ZDE” is the shift amount in the Z direction. In each table, the reference numeral in parentheses corresponding to each surface number is the reference numeral given to each surface in the drawing.

[Table 6]

[Table 7] Incidentally, in this specific example, the optical power of the HOE 27 (focal length 20.2 m) relative to the total optical power of the hologram combiner optical system 21 (focal length 13.7 mm).
The ratio of m) is 0.68.

Further, in this specific example, the incident angle and the exit angle of the principal ray with respect to the HOE 27 are respectively 2
They are 9.30000 ° and 29.31404 °. Also,
The aberration diagrams of this hologram combiner optical system are shown in FIG.
This is as shown in FIGS. 13 and 14. In each figure, "Y-
"FAN" is in the Y direction, "X-FAN" is in the X direction, and "FIE".
“LD HEIGHT” indicates an angle of view (angle in X direction, angle in Y direction).

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a diagram showing a configuration and an optical path (only an optical path from the display surface D) of the hologram combiner optical system of the present embodiment. Here, the second
Only differences from the embodiment will be described, and description of other points will be omitted.

The hologram combiner optical system 31 of the present embodiment also includes the hologram substrate 35 having the HOE 37 formed thereon.
It comprises correction optical systems 38 and 39. Correction optical system 38,
39 is also the correction optical system 28, 29 in the second embodiment.
Similarly, it is a refractive optical system to which positive optical power is given as a whole, and thereby, the function of reducing the chromatic aberration of the hologram combiner optical system 31 is fulfilled.

Further, the correction optical systems 38, 3 of this embodiment
9, the surface 39a closest to the display surface D is the second surface 39a.
Like the surface 29a of the correction optical system 29 in the embodiment, it has a negative optical power, whereby the telecentricity on the incident side of the hologram combiner optical system 31 is kept high and the correction optical system is The aberration correction of the entire 38 and 39 is facilitated.

The present embodiment is different from the second embodiment in that the display surface D is arranged on the user side of the hologram substrate 35. As the display surface D is arranged on the side of the user, the hologram substrate 35 is provided with the inclined reflecting surface 35d similar to the reflecting surface 15d of the hologram substrate 15 of the first embodiment. In addition, the correction optical system 38, 3
The surface 38b closest to the hologram substrate 35 of 9 is the same plane as the incident surface 35c of the hologram substrate 35,
Further, it is fixed to the incident surface 35c with an air gap.

As described above, in the present embodiment as well, as in the second embodiment, the correction optical systems 38 and 39 are made to bear a part of the optical power to reduce the load on the HOE 37, so that the hologram combiner optical system is provided. The overall chromatic aberration of 31 can be suppressed small. [Specific Example of Third Embodiment] Next, the lens data of the hologram combiner optical system, which is a specific example of this embodiment,
The results are shown in Tables 8 and 9.

The specifications of this hologram combiner optical system are as follows. That is, the entrance pupil diameter is 3 mm, and the angle of view is ± 6.66 ° in the X direction and ± 5 ° in the Y direction. The apparent distance to the object is -600.000.
000 mm, wavelength used is 524.44 nm, 51
They are 4.44 nm and 504.44 nm.

The order of the surface numbers is from the pupil P to the display surface D.
With the direction to. In the notation of HOE data,
HV1 is an object point light source, HV2 is a reference point light source, and HTH is H
OE thickness, HIN is HOE refractive index, HDI is HOE
Modulation width of refractive index, HSW is thickness expansion coefficient of HOE, HDN
Is the refractive index shift of HOE, HX1 is the X coordinate of the object point light source, HY1 is the Y coordinate of the object point light source, HZ1 is the Z coordinate of the object point light source, HX2 is the X coordinate of the reference point light source, and HY2 is the Y of the reference point light source. Coordinates, HZ2 is the Z coordinate of the reference point light source, HWL
Is a light source wavelength (unit: nm) at the time of HOE manufacturing.

In Tables 4 and 5, "HOR" is the diffraction order, "XDE" is the shift amount in the X direction, and "YDE".
Is the shift amount in the Y direction, and “ZDE” is the shift amount in the Z direction. In each table, the reference numeral in parentheses corresponding to each surface number is the reference numeral given to each surface in the drawing.

[Table 8]

[Table 9] Incidentally, in this specific example, the optical power of the HOE 37 (focal length 20.5 m) relative to the total optical power of the hologram combiner optical system 31 (focal length 14.4 mm).
The ratio of m) is 0.70.

Further, in this specific example, the incident angle and the outgoing angle of the principal ray with respect to the HOE 37 are 2 and 2, respectively.
They are 9.30000 ° and 29.034343 °. Also,
Aberration diagrams of this hologram combiner optical system are shown in FIG.
This is as shown in FIGS. 17 and 18. In each figure, "Y-
"FAN" is in the Y direction, "X-FAN" is in the X direction, and "FIE".
“LD HEIGHT” indicates an angle of view (angle in X direction, angle in Y direction).

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. FIG. 19 is a diagram showing a configuration and an optical path (only an optical path from the display surface D) of the hologram combiner optical system of the present embodiment. Here, the first
Only differences from the embodiment will be described, and description of other points will be omitted.

The configuration of the hologram combiner optical system of this embodiment is the same as that of the first embodiment. However, in the HOE 47 of the present embodiment, the diffraction pattern is formed on the curved surface (reflection curved surface) with the concave surface facing the eye of the user. That is, in the present embodiment, a part of the optical power of the hologram combiner optical system 41 is
It is also assigned to the reflection curved surface that is the formation surface of the HOE 47.

As a result, the burden of the optical power due to the diffractive action in the HOE 47 can be suppressed to be smaller than that in the first embodiment. Therefore, the overall chromatic aberration of the hologram combiner optical system 11 can be suppressed to be smaller than that in the first embodiment. In this embodiment, the ratio of the optical power of the reflection curved surface to the total optical power of the HOE 47 has been found to be preferably smaller than “5” by a ray tracing simulation.

[Specific Example of Fourth Embodiment] Tables 10 and 11 show lens data of a hologram combiner optical system which is a specific example of this embodiment. The specifications of this hologram combiner optical system are as follows. That is, the entrance pupil diameter is 3 mm, and the angle of view is ± 6.6 in the X direction.
6 ° ± 5 ° in the Y direction. The apparent distance to the object is -600.000000 mm, and the wavelengths used are 524.44 nm, 514.44 nm, and 504.44 n.
m.

The order of the surface numbers is from the pupil P to the display surface D.
With the direction to. In the notation of HOE data,
HV1 is an object point light source, HV2 is a reference point light source, and HTH is H
OE thickness, HIN is HOE refractive index, HDI is HOE
Modulation width of refractive index, HSW is thickness expansion coefficient of HOE, HDN
Is the refractive index shift of HOE, HX1 is the X coordinate of the object point light source, HY1 is the Y coordinate of the object point light source, HZ1 is the Z coordinate of the object point light source, HX2 is the X coordinate of the reference point light source, and HY2 is the Y of the reference point light source. Coordinates, HZ2 is the Z coordinate of the reference point light source, HWL
Is a light source wavelength (unit: nm) at the time of HOE manufacturing.

"HOR" is the diffraction order, and "XDE".
Is the shift amount in the X direction, “YDE” is the shift amount in the Y direction,
“ZDE” is the shift amount in the Z direction. In each table, the reference numeral in parentheses corresponding to each surface number is the reference numeral given to each surface in the drawing.

[Table 10]

[Table 11] Incidentally, in this specific example, the optical power of the HOE 47 (focal length 21.0 m) relative to the total optical power of the hologram combiner optical system 41 (focal length 16.0 mm).
The ratio of m) is 0.76.

Further, in this specific example, the incident angle and the outgoing angle of the principal ray with respect to the HOE 47 are 2 and 2, respectively.
They are 9.30000 ° and 29.0180 °. Also,
In this example, the ratio of the optical power due to the reflection curved surface of the HOE 47 to the total optical power of the HOE 47 is
It is 4.46. Further, in this specific example, the radius of curvature of the surface on which the HOE 47 is formed is −182.39241 mm.

The aberration diagrams of this hologram combiner optical system are as shown in FIGS. 20, 21 and 22. In each figure, "Y-FAN" is the Y direction, and "X-FAN".
Is in the X direction, "FIELD HEIGHT" is the angle of view (X
Direction angle and Y direction angle). [Others] In the above-described first embodiment, second embodiment, and third embodiment, each surface (15
a, 15b, 15c, 15d, 17, 25a, 25b,
27, 35a, 35b, 35c, 35d) are flat surfaces, but if all or a part of them are curved surfaces, even if a part of the optical power to be given to the hologram combiner optical system is applied to the curved surfaces. Good.

For example, in the second or third embodiment, the HOE may be formed on the curved surface as in the fourth embodiment. Further, in the first and third embodiments, the surface 18a of the correction optical system 18 that is closest to the display surface D is provided with positive optical power. The overall optical power of the correction optical system 18 may be set to be positive.

Further, in each of the above-described embodiments, the case where the hologram combiner optical system of the present invention is applied to the head-mounted image display device has been described. However, the hologram combiner optical system of the present invention can be applied to a viewfinder of a camera or a camera. It can be configured so that it can be attached to the eyepiece portion of a microscope and binoculars, or can be configured to be incorporated in a camera, a microscope, binoculars or the like.

[0075]

As described above, according to the present invention,
A hologram combiner optical system capable of suppressing chromatic aberration regardless of monochromaticity of a light source or wavelength selectivity of HOE is realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration and an optical path (only an optical path from a display surface D) of a hologram combiner optical system of a first embodiment.

FIG. 2 is an aberration diagram of the hologram combiner optical system of the first embodiment (first wavelength band, 0 ° in the angle of view X direction).

FIG. 3 is an aberration diagram of the hologram combiner optical system of the first embodiment (first wavelength band, 3.33 ° in the angle of view X direction).

FIG. 4 is an aberration diagram of the hologram combiner optical system of the first embodiment (first wavelength band, angle of view 6.66 ° in the X direction).

FIG. 5 is an aberration diagram of the hologram combiner optical system of the first embodiment (second wavelength band, 0 ° in the angle of view X direction).

FIG. 6 is an aberration diagram of the hologram combiner optical system of the first embodiment (second wavelength band, 3.33 ° in the angle of view X direction).

FIG. 7 is an aberration diagram of the hologram combiner optical system of the first embodiment (second wavelength band, angle of view: 6.66 °).

FIG. 8 is an aberration diagram of the hologram combiner optical system of the first embodiment (the third wavelength band, 0 ° in the angle of view X direction).

FIG. 9 is an aberration diagram (third wavelength band, 3.33 ° in the angle of view X direction) of the hologram combiner optical system of the first embodiment.

FIG. 10 is an aberration diagram of the hologram combiner optical system of the first embodiment (third wavelength band, 6.66 ° in the angle of view X direction).

FIG. 11 is a diagram showing a configuration and an optical path (only an optical path from a display surface D) of a hologram combiner optical system of a second embodiment.

FIG. 12 is an aberration diagram of the hologram combiner optical system of the second embodiment (first wavelength band, 0 ° in the angle of view X direction).

FIG. 13 is an aberration diagram (first wavelength band, 3.33 ° in the angle of view X direction) of the hologram combiner optical system of the second embodiment.

FIG. 14 is an aberration diagram of the hologram combiner optical system of the second embodiment (first wavelength band, field angle X direction: 6.66 °).

FIG. 15 is a diagram showing a configuration and an optical path (only an optical path from a display surface D) of a hologram combiner optical system of a third embodiment.

FIG. 16 is an aberration diagram of the hologram combiner optical system of the third embodiment (first wavelength band, 0 ° in the angle of view X direction).

FIG. 17 is an aberration diagram of the hologram combiner optical system of the third embodiment (first wavelength band, 3.33 ° in the angle of view X direction).

FIG. 18 is an aberration diagram of the hologram combiner optical system of the third embodiment (first wavelength band, field angle X direction: 6.66 °).

FIG. 19 is a diagram showing a configuration and an optical path (only an optical path from a display surface D) of a hologram combiner optical system of a fourth embodiment.

FIG. 20 is an aberration diagram of the hologram combiner optical system of the fourth embodiment (first wavelength band, 0 ° in the angle of view X direction).

FIG. 21 is an aberration diagram (first wavelength band, 3.33 ° in the angle of view X direction) of the hologram combiner optical system of the fourth embodiment.

FIG. 22 is an aberration diagram of the hologram combiner optical system of the fourth embodiment (first wavelength band, angle of view 6.66 °).

[Explanation of symbols]

11,21,31,41 Hologram combiner optical system 15, 25, 35 Hologram substrate 17, 27, 37, 47 Hologram element (HOE) 18, 28, 29, 38, 39 Correction optical system D display surface P pupil

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H049 CA01 CA05 CA09 CA17 CA22                 2H087 KA23 RA42 RA45 RA46 TA01                       TA02 TA04 TA05

Claims (11)

[Claims] 1. A hologram combiner optical system in which a hologram element that guides both light from a predetermined image display element and light from the outside to the user's eyes is arranged, wherein the hologram corresponds to the optical power of the entire optical system. The hologram combiner optical system, wherein the optical power ratio of the element is less than 1. 2. The hologram combiner optical system according to claim 1, wherein the ratio of the optical powers is less than 1 and 0 or more. 3. The hologram combiner optical system according to claim 1, wherein the hologram elements are arranged such that an incident angle and an exit angle of a principal ray are substantially equal to each other. Optical system. 4. A hologram combiner optical system in which a hologram element that guides both light from a predetermined image display element and light from the outside to the eyes of the user is arranged, wherein the diffraction surface of the hologram element is positive. A hologram combiner optical system, which is formed on a curved surface having optical power. 5. The hologram combiner optical system according to claim 4, wherein the ratio of the optical power of the curved surface to the optical power of the entire hologram element is smaller than 5. 6. The hologram combiner optical system according to claim 4, wherein the ratio of the optical power of the hologram element to the optical power of the entire optical system is less than 1. Combiner optics. 7. The hologram combiner optical system according to claim 6, wherein the ratio of the optical powers is less than 1 and 0 or more. 8. The hologram combiner optical system according to any one of claims 4 to 7, wherein the hologram element is arranged so that an incident angle and an exit angle of a principal ray are substantially equal to each other. Characteristic hologram combiner optical system. 9. A hologram combiner optical system in which a hologram element that guides both light from a predetermined image display element and light from the outside to the user's eyes is arranged, and the refractive optical has a positive optical power. System and / or reflective optical system is arranged, a hologram combiner optical system. 10. The hologram combiner optical system according to claim 9, wherein the refraction optical system and / or the reflection optical system also serves as an optical system for guiding light from the image display element to the hologram element, and When the optical axis of the light from the image display element is included in the horizontal plane, the optical axis of the light guided from the image display element and diffracted by the hologram element is also included in the horizontal plane. A hologram combiner optical system characterized by. 11. The hologram combiner optical system according to claim 9 or 10, wherein the refraction optical system and / or the reflection optical system is composed of a plurality of optical surfaces, of which one is closest to the image display element. The hologram combiner optical system, wherein the optical power of the arranged first optical surface is set to be negative.