JPH06118234A - Hologram lens and display device using it - Google Patents

Abstract

PURPOSE:To provide a hologram lens and a display device using it capable of observing the image information in a wide observation visual field at uniform brightness. CONSTITUTION:An off-axis type hologram lens 3 is divided into multiple element holograms 31-33, the element holograms 31-33 have sizes when a virtually set aperture is projected on the hologram lens surface at the preset angle, and the element holograms 31-33 are arranged not to be overlapped each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram lens, a display device using the same, and a method for manufacturing a hologram. For example, an off-axis type hologram lens is used as a light beam coupling element to display an image. Image information from the vessel and front view (behind the hologram lens)
Spatially superimpose with other image information such as the natural scenery of
It is also suitable when observing both image information in the same visual field.

[0002]

2. Description of the Related Art Display information (image information) from a display element and image information such as an external scene are within the same field of view by using an optically transparent light flux coupling element such as a multilayer reflection surface or a hologram optical element. A display device that is spatially superposed for observation is generally called a head-up display device,
It is widely used in each field.

In order to reduce the size of parts of the optical device of the head-up display device, the display device in which the light beam coupling element is provided relatively close to the observer's eye and the optical device is mounted on the helmet is a helmet. It is called a mount display device (HMD device), and is used as a display device when operating an aircraft, for entertainment such as games, or as an artificial reality (Artifici).
Various applications such as display devices for al Reality) have been proposed.

FIG. 9 is an optical path diagram of an HMD device as a display device described in US Pat. No. 3,940,204.

Display light emitted from an image display surface 91 of a CRT (not shown) passes through a prism system 92 and enters a relay lens 93. The relay lens 93 forms an image of display light on an intermediate image forming surface 94 near a hologram combiner 95 formed on a visor (not shown) having an appropriate curvature. The display light, which has become divergent light from the intermediate image formation point, is made into a substantially parallel light flux by the hologram combiner 95 having a lens effect, and enters the pupil 96 of the observer. Therefore, the observer can observe the CRT image (virtual image) formed at infinity by superimposing it on the front scene 97.

In this display device, since the hologram combiner has a large off-axis arrangement, the hologram combiner 95 causes complicated aberrations. Therefore, in this conventional example, the prism system 92 and the CR are used.
The image display surface 91 of T is arranged so as to be tilted, and the aberration generated in the hologram combiner 95 is corrected.

Generally, holograms are small and lightweight and can be mass-produced by a copying method, and thus are used as optical elements in various optical devices.

FIG. 13 is a schematic view of a main part showing a method for producing a hologram as a combiner element described in US Pat. No. 4,530,564.

In the figure, the monochromatic light from the argon laser 71 is split into two. One of the light fluxes is expanded by the microscope objective lens 72, and after the necessary spherical aberration, astigmatism, and coma aberration are corrected by the aberration correction lens system 73, it is reflected by the concave mirror 74 to become convergent light and becomes a hologram on the transparent substrate 75. It enters the recording material 76.

On the other hand, the other split light beam from the argon laser 71 is expanded by the microscope objective lens 77, and after the predetermined astigmatism and coma are corrected by the aberration correction optical system 78, it is transmitted through the transparent substrate 75. Hologram recording material 7
It is incident on 6.

The above two light beams interfere with each other in the hologram recording material 76 to form a volume phase diffraction grating. The hologram recording material 76 is developed to produce a hologram. As the hologram recording material 76, dichromated gelatin or polyvinylcarbazole is used.

[0012]

The display device shown in FIG. 9 uses a curved hologram combiner that is difficult to manufacture and a complicated and heavy relay optical system, which tends to be difficult to mass produce, reduce weight, and reduce size. is there. Further, in order to widen the observation field of view, the size of the hologram combiner must be increased, and accordingly, the amount of aberration of the hologram combiner also increases.

US Pat. No. 3,807,829 and US Pat.
Japanese Patent No. 3,915,548 and the like disclose a head-up display device in which an observation field of view is enlarged by using a hologram lens array.

In the above two publications, a hologram lens is divided into several element holograms, designed and manufactured, and the aberration characteristics in each divided area are improved to observe this in a display device used as a combiner. We are trying to widen the field of view.

However, these publications do not specify how to define the size of each element hologram of the hologram lens array. For example, if all the element holograms have the same size or are determined without considering the observer's pupil position, the diameter of the light beam entering the pupil will vary depending on the diffraction position on the hologram lens array ( Cannot have a constant exit pupil). Therefore, when such a hologram lens array is used as a combiner for a display device such as a head-up display, the virtual image superimposed through the combiner is eclipsed by the observer's pupil.

A first object of the present invention is to appropriately set the configuration of an off-axis type (off-axis type) hologram lens so that the off-axis type hologram lens can be turned off.
Aberrations caused by the axial arrangement are well corrected, and vignetting of the displayed image due to the observer's pupil is corrected, and the image information from the image display and other image information are spatially superposed and uniform in a wide observation visual field. The present invention provides an off-axis type holographic lens capable of observing with the brightness of and a display device using the same.

On the other hand, the hologram manufacturing apparatus shown in FIG. 13 has a problem that the number of parts of the optical system for printing is very large and it is difficult to dispose all of these optical elements at required positions.

Particularly, since the cylindrical lens, the parallel plate, etc. are arranged off the optical axis, a special jig is required for the arrangement. In addition, an optical system having an extremely large diameter is required to manufacture a hologram optical element having a predetermined size.

For example, when manufacturing a hologram optical element having a diameter of 200 mm, the reflecting mirror 74 needs to have a diameter of 400 mm or more, and as a result, the printing optical system becomes very expensive. The interference fringes recorded on the hologram recording material 76 have a pitch of about 0.15 μm, and the vibration during exposure is preferably 0.01 μm or less. For this purpose, it is necessary to make a printing optical system compact and with high rigidity.
A large optical system as shown in FIG. 13 has a problem that it is difficult to manufacture a highly accurate hologram.

A second object of the present invention is to make it possible to manufacture a high-precision hologram while reducing the size and simplification of the entire apparatus, and when the hologram is used as a combiner, image information from an image display device is displayed. Another object of the present invention is to provide a hologram manufacturing method capable of spatially superimposing other image information and other image information for good observation in the same visual field, and a display device using the hologram manufacturing method.

[0021]

The hologram lens of the present invention is (1-1) an off-axis type hologram lens, wherein the hologram lens is divided into a plurality of element holograms, and each element hologram is virtual. It is characterized in that it has a size when a diaphragm that is set to a predetermined angle is projected onto the surface of the hologram lens at a predetermined angle, and that the element holograms are arranged so as not to overlap each other.

(1-2) In an off-axis type hologram lens, the hologram lens is divided into a plurality of element holograms, and each element hologram has a diaphragm that is virtually set on a predetermined plane or curved surface. It is characterized in that it has a size when it is projected at a predetermined angle with a convergent light beam that converges to the point, and that the element holograms are arranged so that they do not overlap.

Particularly in (1-1) and (1-2), the hologram lens is a volume phase hologram.

(1-3) The light flux based on the image information from the image display is off-ax composed of a plurality of element holograms.
Each element hologram is virtually set when the image information and the image information behind the hologram lens are spatially superposed and observed in the same field of view by diffracting in a predetermined direction through an is-type hologram lens. The above-mentioned stop has a size when projected onto the surface of the hologram lens at a predetermined angle, and is arranged so that the element holograms do not overlap each other.

(1-4) The light flux based on the image information from the image display is off-ax composed of a plurality of element holograms.
When the image information and the image information behind the hologram lens are spatially superimposed and observed in the same field of view by diffracting through the is-type hologram lens, each element hologram has a virtually set diaphragm. It has a size when projected at a predetermined angle with a convergent light beam that converges to a point on a predetermined plane or curved surface, and it is arranged so that each element hologram does not overlap. Is characterized by.

Particularly in (1-3) and (1-4), the hologram lens is a volume phase hologram.

As the hologram production method of the present invention, (1-5) when the object light and the reference light are made incident on the recording medium from different directions to form interference fringes on the recording medium, a hologram is produced: At least one of the object light optical system for generating the object light and the reference light optical system for generating the reference light is provided with a cylindrical lens and a computer generated hologram.

(1-6) A light beam passing through an optical system including a cylindrical lens and a computer generated hologram and a light beam of a convergent spherical wave or a divergent spherical wave are made incident on the recording medium from different directions, and interference fringes are made on the recording medium. It is characterized in that a hologram is formed by forming.

In addition, in the present invention, (1-5), (1-
It is characterized in that a plurality of element holograms produced by the method 6) are arranged on a plane to produce a hologram, and the computer generated hologram is an off-axis type hologram.

As the display device of the present invention, (1-7) the light flux based on the image information from the image display is diffracted through the hologram lens in a predetermined direction to obtain the image information and the image behind the hologram lens. When the information and the information are spatially superposed and observed in the same field of view, the hologram lens is a cylindrical lens in at least one of an object light optical system for generating an object light and a reference light optical system for generating a reference light. And a volume hologram hologram lens produced by causing object light and reference light to enter a recording medium from different directions using a system provided with a computer generated hologram and forming interference fringes on the recording medium. There is.

(1-8) The light flux based on the image information from the image display is diffracted through the hologram lens, and the image information and the image information behind the hologram lens are spatially superposed and the same field of view is obtained. At the time of observation, the hologram lens causes a light beam passing through an optical system including a cylindrical lens and a computer generated hologram and a light beam of a convergent spherical wave or a divergent spherical wave to enter the recording medium from different directions, and interferes with the recording medium. It is characterized in that it is a volume phase hologram lens produced by forming stripes.

[0032]

EXAMPLE 1 FIG. 1 shows Example 1 of the hologram lens of the present invention.
FIG. In the figure, 3 is off-axis
It is an s-type hologram lens.

In this embodiment, the hologram lens 3 is composed of a hologram lens array having three element holograms 31, 32 and 33. Reference numeral 2 is a substrate on which a hologram lens 3 is formed. 1
Is a virtually set diaphragm surface, and corresponds to the position of the observer's pupil when applied to a display device. An image plane 5 corresponds to the position of the image information of the image display when applied to the display device.

Reference numeral 107 denotes other image information such as a natural landscape. When the image information is arranged on the image plane 5, both image information are spatially superimposed via the hologram lens 3 and observed in the same visual field. There is.

Next, the optical characteristics when the hologram lens array 3 is composed of three element holograms 31, 32 and 33 will be described.

First, the on-axis light flux will be described. In the figure, a monochromatic light beam having a wavelength λ enters the hologram lens array 3 on the substrate 2 from the virtual diaphragm surface 1 at an incident angle θ ₁ .

Of these, the element hologram 31 reflects and diffracts the axial luminous flux as a luminous flux 4 at an angle θ ₂ . At this time, the element hologram 31 is configured so as to satisfy the Bragg condition only for the light flux of the wavelength λ that is incident at the incident angle θ ₁ , and the wavefront conversion into the convergent light flux 4 is performed on the image plane 5. The light is focused on the image formation point F1.

The light beams from the virtual diaphragm surface 1 have the same incident angle θ.
_{At 1} , the light also enters the other element holograms 32 and 33 of the hologram lens array 3. However, these element holograms 32 and 33 do not satisfy the Bragg condition at the incident angle θ ₁ and do not have a predetermined diffraction efficiency.

In this embodiment, in this way, only the axial light beam is diffracted by the element hologram 31 and focused on the image forming point F1.

On the other hand, with respect to the light beam entering the hologram lens array 3 at the angle of view + ω, only the element hologram 32 satisfies the Bragg condition and is focused on the image forming point F2. Similarly, a light flux incident at an angle of view of -ω is focused on the image forming point F3.

In this embodiment, the hologram lens array 3 is used.
The central wavelength of the light beam to be imaged by 530 nm, the aperture diameter of the virtual diaphragm 1 is 10 mm, and the hologram lens array 3
The incident angle θ _{1 of} light incident on the center C1 is 60 °, the diffraction angle is θ ₂ = 20 °, and the focal length of the element hologram 31 is f ₃₁ = 50 mm.

The distance from the center point C1 of the element hologram 31 to the center of the virtual diaphragm 1 is also 50 mm. Each element hologram 31, 32, 33 is divided into a size corresponding to the size of the incident light beam of each angle of view on the hologram surface when the diameter of the virtual diaphragm 1 is fixed.

That is, assuming that the incident angle of the axial light beam on the hologram center C1 is θi, the angle of view is ωi, and the diameter of the virtual diaphragm 1 is a, the size H of the incident light beam on the hologram surface is H = a.
/ Cos (θi + ωi), each angle of view is -10
If the angles are 0 °, 0 °, and 10 °, the size of each element hologram in the meridional direction is 20.0 m for the element hologram 31.
m, the element hologram 32 is 29.24 mm, and the element hologram 33 is 15.56 mm.

According to the present invention, as described above, the size of the element hologram is set so that the hologram lens array 3 is made incident from the stop having the same position and the same diameter as the virtual stop 1 within the predetermined angle of view. The parallel light flux to be generated is capable of generating the image plane 5 having uniform brightness.

At the same time, the image plane 5 formed by the points F1, F2, f3, etc. of the image plane 5 is imaged as a virtual image plane 107 at infinity by the hologram lens array 3 and is formed at the position of the virtual diaphragm 1. By observing with the observer's eyes placed, a virtual image without vignetting can be observed.

In this embodiment, off-axis is used.
The method of dividing the vertical hologram lens array in the vertical direction was explained, but similarly in the horizontal direction, each element hologram corresponds to the size on the hologram surface of the incident light beam of each angle of view that passes through the virtual diaphragm with a constant diameter. It is divided into different sizes.

FIG. 2 is a schematic diagram of Embodiment 2 of the hologram lens of the present invention. In this embodiment, the hologram lens array is composed of 5 × 5 element holograms.

The element hologram indicated by (i, j) (i, j = -2 to 2) in the figure is compared with the element hologram (0,0) for the axial light flux including the point C1 which is the optical axis. , The angle of view ω = 10 × j ° in the vertical direction, and the angle of view ω = 1 in the horizontal direction.
The number of each angle of view of 0 × i ° is shown. For example, in the case of element hologram (i, j) = (2,2), the angle of view + ω in the horizontal direction
= + 20 °, the angle of view + ω = + 20 ° in the vertical direction, and the element hologram (i, j) = (-1, + 1) is an incident light beam having an angle of view of −10 ° in the horizontal direction and an angle of view of + 10 ° in the vertical direction. 3 shows an element hologram that acts on.

As described above, since the size of each element hologram corresponds to the size of the incident light beam on the hologram surface, the size of each element hologram is + in the horizontal direction.
The larger the angle of view in both the negative and negative directions, the greater the angle of view, and the larger the angle of view in the + direction, the smaller the angle of view in the negative direction.

In the present invention, the number of element holograms forming the hologram lens array is such that the in-plane grating pitch is equal at the boundary between the element holograms, and the incident angle and the diffraction angle satisfy the grating equation. There may be any number as long as each element hologram is set so as to satisfy the Bragg condition only for the light flux of the angle of view using the element hologram.

In each of the above embodiments, the reflection type off-
Although the description has been given of the axis type hologram lens array, the same is applicable to a transmission type off-axis type hologram lens array.

Next, a method of manufacturing the off-axis type hologram lens array of the present invention will be described by taking the element hologram 31 of FIG. 1 as an example. The method of creating the other element holograms is basically the same.

First, as shown in FIG. 1, the element hologram 3
1 is a point C1 on the surface of the hologram, and the in-plane lattice pitch P is
_C1 = 1.011 [mu] m, the grating inclination angle φ _C1 = 11.042 °, has a lattice constant which is a lattice spacing d _C1 = 0.1937μm.

At point C2, P _C2 = 1.446 μm, φ _C2 = 7.9
06 °, d _C2 = 0.199 μm, P _C3 = 0.522 μ at point C3
m, φ _C3 = 20.487 °, d _C3 = 0.183 μm.

A method of recording element holograms having these lattice constants on a photosensitive material having a refractive index of 1.5 using an argon ion laser having a recording wavelength of 514.5 nm will be described with reference to FIG.

Laser light having a wavelength of 514.5 nm emitted from the argon ion laser 11 in FIG.
The light beam is divided into two light beams by 2 and collimated by the collimator lens systems 13a and 13b.

One of the parallel luminous fluxes La is incident on the lens system 15 arranged with β1 inclined with respect to the optical axis and reflected by the mirror 16. A reflected light beam 19 from the mirror 16 is incident on a photosensitive material 18 coated or attached on a transparent substrate 17. The incident light beam 19 is an off-axis light beam having an angle of view β1 of the lens system 15, and is off in the off-axis type hologram lens according to the present invention.
-Aberration caused by the axial arrangement, wavelength at the time of use (reproduction) (530 nm in this embodiment) and recording light wavelength (51
The reverse aberration is generated to correct the aberration and the like caused by the wavelength difference from 4.5 nm.

The other parallel light beam Lb is reflected by the mirror 20 and is arranged at a tilt of β2 with respect to the optical axis.
At 1, the convergent light beam 22 including aberration is incident on the photosensitive material 18.

These light beams 19 and 22 are made incident on the photosensitive material 18 at the incident angles θ _r1 and θ _r2 from opposite sides to interfere with each other. A reflective hologram is recorded from this.

As the recording material 18 used in this embodiment, various materials such as dichromated gelatin, photopolymer, and silver salt sensitive material can be used. In the embodiment shown in FIG. 3, the photopolymer is used. There is.

FIG. 4 is an explanatory diagram of a light beam exaggeratedly showing the two light beams 19 and 22 incident on the photosensitive material 18 of the recording optical system.

FIG. 5 is an explanatory view showing the incident angles of the recording laser light at the points C1, C2 and C3 on the surface of the present element hologram 31.

At the point C1 in the figure, θ _r1 (C1) = 69.72
°, θ _r2 (C1) = 25.41 ° At point C2 θ _r1 (C2) = 68.48 °, θ _r2 (C2) =
35.06 ° At point C3, θ _r1 (C3) = 77.75 °, θ _r2 (C3) =
It is −0.48 °, and the light beams 19 and 22 incident at such an angle are realized by the optical system on the optical path of each light beam.

In the present invention, the hologram lens array is produced by recording each element hologram by means of the step & repeat method using the method described above.

At this time, when recording another element hologram, the incident angle of the light beam to the center of the element hologram is set by rotating the mirrors 16 and 20. Further, the incident light beams 19 and 22 are limited by using a mask (not shown) or a spatial light modulator (not shown) such as a liquid crystal according to the size of the element hologram.

In the present embodiment, the method of recording the element hologram by using the aberration light beam due to the off-axis light beam of the rotationally symmetric lens system is used, but recording optics such as a lens system including a cylindrical lens or a decentered lens is used. It is also possible to use a system.

Further, the lens system 15 for generating the aberration,
Reference numeral 21 is a collimated beam, but instead of the collimation system 13 of this embodiment, a concave lens or a convex lens,
The lens systems 15 and 21 may be configured as a finite image forming system by diverging light using a microscope objective lens or the like.

As described above, the size of each element hologram is set so that the size of the off-axis type hologram lens array when the virtual diaphragm is projected on the surface thereof becomes equal, and thereby the entire hologram is covered. A wide-angle off-axis type hologram lens array with uniform brightness is configured.

FIG. 6 is a schematic view of the essential portions of Embodiment 3 of the hologram lens of the present invention. The present embodiment is different from the first embodiment in that a monochromatic light beam having a wavelength λ that is incident from the virtually set diaphragm 1 is not a parallel light beam but a convergent light beam.

Therefore, the size of each divided element hologram is different from that of the first embodiment. In this embodiment, the size of each element hologram is determined as follows. First, the light flux on the axis will be described. Virtual diaphragm surface 1
The more convergent light beam 101 is incident on the hologram lens array 3 formed on the substrate 2 at an incident angle θ1. The convergent luminous flux 10
1 converges to a point T1 on the axis in front of the center O of the hologram lens array 3 by a distance f. However, the point T1 is a point on the virtual image plane 10.

Here, points PA and PB indicate the upper opening and the lower opening of the virtual diaphragm 1. A point A1 at which the outermost light ray of the convergent light flux 101 intersects with the hologram lens array 3.
The area from to point B1 is the element hologram 31. At this time, the point A1 at the upper end of the element hologram 31 becomes the intersection of the straight line T1PA connecting the points T1 and PA and the hologram lens array 3, and the point B1 at the lower end of the element hologram 31.
Is an intersection of a straight line T1PB connecting the points T1 and PB and the hologram lens array 3.

Next, the lower end PB of the aperture of the virtual diaphragm 1 and the point A
Assuming that the point where the straight line connecting 1 and 1 intersects the virtual image plane 10 is T2, from the point A1 where the outermost edge ray of the convergent beam 102 that passes through the virtual diaphragm 1 and converges to the point T2 intersects the hologram lens array 3 to point A2. Is defined as an element hologram 32. At this time, the point A2 at the upper end of the element hologram 32 is the intersection of the straight line T2PA connecting the points T2 and PA and the hologram lens array 3.

Similarly, assuming that the point where the straight line connecting the upper end PA of the virtual diaphragm 1 and the point B1 intersects the virtual image plane 10 is T3, the convergent light flux 103 that passes through the virtual diaphragm 1 and converges to the point T3.
Point B where the outermost ray of the light intersects the hologram lens array 3
The area from 1 to the point B2 is the element hologram 33.
At this time, the point B2 at the lower end of the element hologram 33 is a straight line T3PB connecting the points T3 and PB and the hologram lens array 3
It becomes the intersection with.

In this embodiment, as in the first embodiment, the element hologram 31 is recorded only in the convergent light beam 101 so as to satisfy the Bragg condition.
The element 1 is reflected and diffracted only by the element hologram 31, and is focused on the point F1 on the image plane 5.

Similarly, the element holograms 32 and 33 are recorded so that only the convergent light beams 102 and 103 satisfy the Bragg condition, whereby the convergent light beams 102 and 103 are recorded.
Is reflected and diffracted only by the element holograms 32 and 33, and is condensed to the points f2 and F3.

In this embodiment, the central wavelength of the light beam focused by the hologram lens array 3 is 530 nm,
The size of the virtual diaphragm 1 is 10 mm, the incident angle of incidence on the center C of the hologram lens array 3 is θ1 = 60 °, and the diffraction angle is θ.
2 = 20 °, the distance from the center of the element hologram 31 to the image plane 5 was 50 mm, and the distance from the point C1 to the center of the virtual diaphragm 1 was also 50 mm.

At this time, considering a coordinate system in which the center of the virtual diaphragm 1 is the origin, the straight line PAPB is the y axis, and the optical axis is the x axis, the point A1 at the upper end of the element hologram 31 = (58.18,4.7).
2) (However, all units are mm, the same applies below), point B at the bottom
1 = (41.68, −4.80), and the size of the element hologram 31 in the meridional direction is 19.05 mm. The point A2 at the upper end of the element hologram 32 is (80.68, 17.72), and the size of the element hologram 32 in the meridional direction is 25.98 mm. Further, the point B2 at the lower end of the element hologram 33 is (29.72, -11.71), and the size of the element hologram 33 in the meridional direction is 13.81 mm.

According to the present embodiment, the divergent light beam incident on the predetermined range of the hologram lens array 3 when the light beam is traced backward from the point on the image plane 5 is reflected and diffracted, and then the virtual diaphragm having a constant diameter. It becomes a divergent light flux which is incident on 1. At the same time, the image plane 5 is made into a virtual image plane 10 by the hologram lens array 3.
Then, a virtual image without vignetting can be observed by observing with the observer's pupil placed on the virtual diaphragm 1.

The method of dividing the hologram lens of this embodiment also determines the size of each element hologram in the horizontal direction, has more element holograms, and is a transmissive off-axis type as in the first embodiment. It can be applied to a division method such as a hologram lens array.

Next, a method of manufacturing the off-axis type hologram lens array of the present invention will be described. If the refractive index of the photosensitive material is 1.5, the element hologram 31
Is an in-plane lattice pitch PC at a point C1 on the surface of the hologram.
1 = 1.011 μm, lattice tilt angle φ′C1 = 11.042 °, lattice spacing dC1 = 0.194 μm. Point C2
Then PC2 = 1.416 μm, φC2 = 80.70 °, dc2 =
0.199 μm, PC3 = 0.908 μm at point C3, φC3 =
12.192 °, dc3 = 0.192 μm.

A method of recording element holograms having these lattice constants on a photosensitive material having a refractive index of 1.5 using an argon ion laser having a recording wavelength of 514.5 nm will be described.

In this embodiment, a photopolymer is used as the recording material. The basic configuration of the recording optical system of the hologram lens array of this embodiment is the same as that of the first embodiment. An outline of the recording optical system of the hologram lens array of the present embodiment is performed by the method shown in FIG. The angle of incidence at each point of the light beam incident on the photosensitive material will be described below using the reference numerals used in FIGS. 4 and 5.

In this embodiment, the incident angle of the light beam 19 on each point is θ _r1 (C1) = 69.72 ° at the point C1, and θ _r1 (C at the point C2.
2) = 68.91 °, θ _r1 (C3) = 70.14 ° at point C3
Is.

On the other hand, the incident angle of the light beam 22 is θ at the point C1.
_r2 (C1) = 25.41 °, θ _r2 (C2) = 34.73 at point C2
At the point C3, θ _r2 (C3) = 21.97 °.

The hologram lens array of the present invention can be manufactured by recording each element hologram by means such as the step & repeat method using the light flux satisfying the incident angle described above.

The formation of the aperture for the element hologram, the method of producing the hologram, the adjustment of the incident light beam, the method of generating aberration, etc. are the same as in the first embodiment.

FIG. 7 is a schematic view of the essential portions of Embodiment 4 of the present invention. In this embodiment, the hologram lens 3 shown in FIG. 1 is used as a light beam coupling element for a helmet mount display device (HMD.
(Apparatus) is shown. In FIG.
The same elements as those shown in are given the same reference numerals.

In this embodiment, the light source 6 such as a halogen lamp is used.
The light flux emitted from the light source 3 is made into a substantially parallel light flux by the lamp house 62 having an appropriate shape, and illuminates the liquid crystal display element 61 as the image information of the image display. Liquid crystal display element 61
Luminous flux 4 emitted from the image information of the point F1 on the display surface 5 of
Enters the hologram lens array 3 formed on the transparent substrate 2 such as glass or plastic.

The hologram lens array 3 has an element hologram 31 satisfying the Bragg condition only for the light beam 4, and the light beam 4 is reflected and diffracted only by the element hologram 31 and corresponds to the virtual diaphragm 1 in FIG. The light enters the pupil 1 of the observer. At this time, the element hologram 31 has a lens function of converting the light beam 4 into a parallel light beam. The observer displays the image information of the point F1 on the display surface 5 on the hologram lens array 3
It is observed in a state without vignetting as a virtual image based on the light beam 4a diverging from the point F1a at infinity in front of.

For the same reason, the luminous flux emitted from the image information at the points F2 and F3 on the display surface 5 of the liquid crystal display element 61 is reflected and diffracted in the direction of the observer's pupil 1 only by the element holograms 32 and 33, respectively. . As a result, point F
The image information of 2 and F3 is observed without vignetting as a virtual image based on the light beams diverging from the points F2a and F3a at the infinite front of the hologram lens array 3.

As described above, the display surface 5 of the liquid crystal display element 61.
The above points are reflected and diffracted by the element holograms 31, 32, and 33 to form the virtual image plane 10.

Even if a white light source is used in the present invention, since the element hologram has wavelength selectivity (diffraction efficiency depends on wavelength), the central wavelength λ ₀ satisfying the Bragg condition.
Has a peak of diffraction efficiency. At this time, when the full width at half maximum is set to 2Δλ, the element hologram causes the reflection diffraction action only for the light flux of λ ₀ −Δλ to λ ₀ + Δλ in the incident white light. Therefore, in this embodiment, a halogen lamp is used as the light source.

As described above, in this embodiment, the reflection off-axis is reflected.
-Type holographic lens array was used to construct a helmet-mounted display device.
The same configuration can be achieved by using an s-type hologram lens array.

Further, in the present embodiment, only the case where the image surface of the hologram lens array 3 and the display surface 5 of the liquid crystal display element 61 are made to coincide with each other has been described, but a CRT or a liquid crystal display element is formed by using a relay lens. The display surface may be converted into the intermediate image forming surface of the relay lens so that the intermediate image forming surface coincides with the display surface 5 of the present embodiment (the object surface of the hologram lens array).

FIG. 8 is a schematic view of the essential portions of Embodiment 5 of the present invention. In this embodiment, the hologram lens 3 shown in FIG. 6 is used as a light beam coupling element for a helmet mount display device (HMD).
(Apparatus) is shown. In FIG.
The same elements as those shown in are given the same reference numerals.

The basic configuration of this embodiment is the same as that of the fourth embodiment shown in FIG. 7, but is different from the fourth embodiment in that the virtual image plane 10 observed by the observer is at a finite distance.

In this embodiment, a light source 63 such as a halogen lamp is used.
The light flux emitted from the lamp is made into substantially parallel light by the lamp house 62 having an appropriate shape, and illuminates the liquid crystal display element 61 as the image information of the image display. The light flux 4 emitted from the image information at the point F1 on the display surface 5 of the liquid crystal display element 61 is
The light enters a hologram lens array 3 formed on a transparent substrate 2 such as glass or plastic.

The hologram lens array 3 has an element hologram 31 which satisfies the Bragg condition only for the light beam 4, and the light beam 4 is reflected and diffracted only by the element hologram 31 and corresponds to the virtual diaphragm 1 in FIG. Observer's eyes 1
Incident on.

At this time, the element hologram 31 has a lens function of converting the light beam 4 into a slight divergent light beam.
The observer observes the image information at the point F1 on the display surface 5 as a virtual image based on the light flux 101 diverging from the point T1 on the virtual image surface 10 at a distance f1 in front of the hologram lens array 3 without vignetting.

For the same reason, the luminous fluxes emitted from the image information at the points F2 and F3 on the display surface 5 of the liquid crystal display element 61 are reflected and diffracted in the direction of the observer's pupil 1 only by the element holograms 32 and 33, respectively. . As a result, the point F2
The image information of F3 is observed as a virtual image based on the light beam diverging from the points T2 and T3 at the distance f1 in front of the hologram lens array 3 without vignetting.

As described above, the display surface 5 of the liquid crystal display element 61.
The above points are reflected and diffracted by the element holograms 31, 32, and 33 to form the virtual image plane 10.

In this embodiment, a halogen lamp is used as a light source for the same reason as in the fourth embodiment.

As described above, in this embodiment, the reflection off-axis is obtained.
-Type holographic lens array was used to construct a helmet-mounted display device.
The same configuration can be achieved by using an s-type hologram lens array.

Further, in the present embodiment, only the case where the image surface of the hologram lens array 3 and the display surface 5 of the liquid crystal display element 61 are made to coincide with each other has been described, but a CRT or a liquid crystal display element is formed by using a relay lens. The display surface may be converted into the intermediate image forming surface of the relay lens so that the intermediate image forming surface coincides with the display surface 5 of the present embodiment (the object surface of the hologram lens array).

As described above, in Examples 1 to 5, o
By dividing the size of each element hologram into a size corresponding to the diameter of the light beam incident from the virtual aperture of the ff-axis type hologram lens array, it is possible to form an image plane of uniform brightness.

Further, in the display device in which the off-axis type hologram lens array is used, the information light from the CRT or the liquid crystal display element is reflected and diffracted to the observer's pupil to observe the image information. Since all the luminous fluxes from the light enter into the diaphragm which is virtually set, when the observer's pupil is placed at this virtual diaphragm position, a virtual image on a large screen without vignetting can be satisfactorily observed.

FIG. 10 is a schematic view of the essential portions of Embodiment 6 of the present invention. In this embodiment, an optical system (printing optical system) for manufacturing a hologram lens is shown.

In FIG. 10, an argon ion laser 20 is shown.
The laser light 202 having a wavelength of 514.5 nm from 1 is split into two light beams by a half mirror 203. One of these optical paths is an object light optical system that generates object light, and the other optical path is a reference light optical system that generates reference light. The light beam 202a reflected by the half mirror 203 is reflected by the mirror 205.
And the collimator lens 207 collimates the parallel luminous flux 20.
The light enters the converging lens 209 as 8. Converging lens 20
The light flux converged at 9 is converted into a convergent spherical wave 210 having a predetermined radius of curvature so as to converge at a point F, and is incident on a hologram photosensitive material 212 coated or attached on a transparent substrate 211 such as glass.

On the other hand, the luminous flux 2 transmitted through the half mirror 203
02b is reflected by the reflecting mirror 204, and the microscope objective lens 21
3 to enlarge the beam diameter, then collimator lens 21
Then, a parallel light beam 215 is incident on a computer hologram (hereinafter referred to as “CGH”) 216 having a configuration described later at a predetermined incident angle.

Of the diffracted light from the CGH 216, the first-order diffracted light 218 is converted through the cylindrical lens 219 into a light beam 220 having a wavefront mainly having astigmatism, and the substrate 2
The light enters the hologram recording material 212 provided on No. 11.

The two light fluxes 210 and 220 incident from both sides of the hologram recording material 212 interfere with each other, and the interference fringes are recorded on the hologram recording material 212. The hologram recording material 212 undergoes a known development process to produce a hologram lens.

In this embodiment, the first-order diffracted light 218 is incident on the cylindrical lens 219 at an angle of about 8 degrees so that the parallel light beam 215 incident on the CGH 216 is diffracted and the 0th-order light 217 does not enter the cylindrical lens 219 when it exits. Each element to be incident on the CGH216
And the cylindrical lens 219 are appropriately set.

As the cylindrical lens 219, a plano-convex focal length 125 mm having a flat surface facing the hologram recording material 212 is used.

Next, a method of manufacturing the computer generated hologram 216 of this embodiment will be described.

Conventionally, in order to manufacture CGH, a method of forming an enlarged hologram by an XY plotter and optically reducing and exposing this was taken.

However, in this method, an error in the optical system and its arrangement is included in the reduction process, and a CGH having sufficiently satisfactory performance could not be obtained especially in the hologram of high NA.

However, in recent years, it has become possible to perform fine processing by the electron beam exposure (EB exposure) method with the improvement of the semiconductor integrated circuit manufacturing technique. If this EB exposure method is used, a fine pattern can be formed on the hologram photosensitive material, and reduction using an optical system is unnecessary, so that a high performance CGH can be obtained. As the photosensitive material for EB exposure CGH, poly-methyl methacrylate (p-MMA), poly-t-putyl methacrylate (p-BMA), poly-methacrylic anhydride (p-MA.AN)
) Etc., a grating having a submicron line width can be manufactured.

In this embodiment, CGH obtained by EB exposure of P-MMA is used.

FIG. 11 is a schematic view of the essential portions of Embodiment 7 of the present invention. The present embodiment shows a case where a hologram lens array including a plurality of element holograms divided into a plurality of regions is manufactured. For simplicity, the figure shows a case where the two element holograms 212-1 and 212-2 are included, but the number may be any number.

FIG. 11A shows an optical path in the vicinity of the hologram recording material 212-2 when the first element hologram 212-1 is recorded by using the optical system shown in Example 6 of FIG.

In the figure, the monochromatic light from the laser light source is convergent spherical waves 210 and C which are focused on the point F as described in the sixth embodiment.
The GH 216 and the wavefront 220 that has been aberrated by the cylindrical lens 219 enter the hologram recording material 212-1 on the substrate 11 from opposite sides. Then, the first interference fringes are recorded on the hologram recording material 212-1.

Next, using the same optical system as in Example 6,
Second interference fringes are recorded on the hologram recording material 212-2. FIG. 11B is a schematic diagram in the vicinity of the hologram recording material 212-2 of the optical system for recording the second interference fringes at this time.

The second interference fringes are such that the spherical wave 210a diverging from the point F and the two light fluxes of the wavefront 220a which are aberrated by the CGH 216 and the cylindrical lens 219 face the hologram recording material 212-2. Interference fringes are recorded on the hologram recording material 212-1.

In the present embodiment, when each element hologram is exposed, light is shielded by using a dry plate holder or the like so as to prevent unnecessary light from entering a portion other than the exposed portion of the hologram recording material. Means are provided.

In this embodiment, each element hologram 212 is also included.
-1 and 212-2 show the case where the holograms are connected so that the edges of the holograms are adjacent to each other, but the optical characteristics of the element holograms in this embodiment have the same function of condensing the reproduction light to the point F. Therefore, even if there is some overlap area between each element hologram, it does not matter at all.

In this case, the phase of each element hologram does not necessarily have to be the same.

The hologram obtained in the above-mentioned embodiment can improve many defects as compared with the case where the conventional hologram manufacturing method is used.

The optical system for hologram production of the present embodiment is greatly simplified as compared with the conventional optical system shown in FIG. 13, and a general product can be used. As shown in FIG. 10, the laser 202 is replaced with a microscope objective lens 206, 2
Spread as a spherical wave through 13 and collimator lens 2
The optical system that collimates the light with 07 and 214 is rotationally symmetric with respect to the optical axis and easy to center, and it is possible to use inexpensive products that are used in large quantities in other fields for each lens. Is.

If the objective lenses 206 and 213 for the microscope are used for a metal microscope with infinity correction, there is almost no aberration, and the collimator lenses 207 and 214 can be objective lenses for telescopes or telephoto lenses for photography.

The minimum diameter of the lens used here is sufficient, and it suffices to cover the required area of the element hologram. Further, in the manufacturing method shown in FIG. 11, since the printing area required for one exposure may be small, a significantly inexpensive optical system can be used.

Further, as a secondary advantage, if the exposure time required for printing is a small area, the product can be improved in yield because it can be completed in a shorter time. In the present invention, since the pitch of the diffraction grating used in the direction perpendicular to the grating is about 0.15 μm, even a slight vibration at the time of exposure causes a drastic decrease in diffraction efficiency. The benefits of shortening are large.

FIG. 12 is a schematic view of the essential portions of Embodiment 8 of the present invention. In this embodiment, an image observation apparatus using the hologram lens 212 manufactured by the method described in FIG. 11 as a light beam coupling element is shown.

In this embodiment, the light source 30 such as a halogen lamp is used.
The light flux emitted from the lamp 8 is converted into substantially parallel light by the lamp house 307 having an appropriate shape, and illuminates the liquid crystal display element 306 as the image information of the image display. Liquid crystal display element 3
The light flux 304 emitted from the image information of the point F1 on the display surface 305 of 06 enters the hologram lens array 303 formed on the transparent substrate 302 such as glass or plastic.

The hologram lens array 303 uses the light beam 3
The element hologram 331 that satisfies the Bragg condition is provided only for 04, and the light beam 304 is reflected and diffracted only by the element hologram 331 and enters the observer's pupil 301. At this time, the element hologram 331 has a lens function of converting the light beam 304 into a slightly divergent light beam. The observer observes the image information at the point F1 on the display surface 305 as a virtual image based on the light beam 304a diverging from the point F1a in front of the hologram lens array 303.

For the same reason, the luminous fluxes emitted from the image information at the points F2 and F3 on the display surface 305 of the liquid crystal display element 306 are reflected and diffracted in the direction of the observer's pupil 301 only by the element holograms 332 and 333, respectively. . Thereby, the image information of the points F2 and F3 is observed as a virtual image based on the light flux diverging from the points F2a and F3a in front of the hologram lens array 303.

As described above, each point on the display surface 305 of the liquid crystal display element 306 corresponds to each element hologram 331, 332, 3
It is reflected and diffracted at 33 to form a virtual image plane 309.

In the present invention, even if a white light source is used, since the element hologram has wavelength selectivity (wavelength dependence of diffraction efficiency), the central wavelength λ ₀ satisfying the Bragg condition is satisfied.
Has a peak of diffraction efficiency. At this time, if the full width at half maximum is set to 2Δλ, the element hologram causes the reflection diffraction action only for the light flux of λ ₀ −Δλ to λ ₀ + Δλ in the incident white light. Therefore, in this embodiment, a halogen lamp is used as the light source.

Further, as a matter of course, it is possible to use an interference filter which transmits only the light flux from the halogen lamp and the light flux of the required wavelength. In addition, in this embodiment, each element hologram 331, 332, 333 has areas 361, 362, 363 whose aberrations are well corrected, and the points on the virtual image plane 9 formed by the areas 361a, 362a, 363a are It can be observed as a point image with almost no aberration.

As described above, according to Embodiments 6 to 8, it is possible to manufacture a hologram with a simple structure, and it is only necessary to change the computer hologram (CGH) with respect to the specification change at the time of reproducing the hologram (in use). It is possible to deal with the problem, and further, by dividing and exposing the hologram, it is possible to remove the adverse effect due to vibration or the like during the exposure.

[0140]

As described above, according to the present invention, by properly setting the configuration of the off-axis type (off-axis type) hologram lens, the aberration caused by the off-axis arrangement of the hologram lens is improved. And the vignetting of the displayed image due to the observer's eyes,
(EN) An off-axis type hologram lens capable of spatially superimposing image information from an image display and other image information and observing with a uniform brightness in a wide observation field, and a display device using the same. can do.

Further, according to the present invention, by setting the optical system as described above, it is possible to manufacture a highly accurate hologram while reducing the size and simplification of the entire apparatus, and use the hologram as a combiner. In this case, it is possible to achieve a hologram manufacturing method and a display device using the same, in which the image information from the image display and the other image information are spatially overlapped and can be observed well in the same visual field.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of Example 1 of a hologram lens of the present invention.

FIG. 2 is a schematic view of a main part of Example 2 of the hologram lens of the present invention.

FIG. 3 is a schematic view of a main part of a method of manufacturing a hologram lens of the present invention.

FIG. 4 is a schematic view of a main part of a method of manufacturing a hologram lens of the present invention.

FIG. 5 is a schematic view of a main part of a method of manufacturing a hologram lens of the present invention.

FIG. 6 is a schematic view of a main part of Example 3 of the hologram lens of the present invention.

FIG. 7 is a schematic view of Example 4 of a display device using the hologram lens of the present invention.

FIG. 8 is a schematic view of Example 5 of a display device using the hologram lens of the present invention.

FIG. 9 is a schematic view of a main part of a display device using a conventional hologram lens.

FIG. 10 is a schematic view of the essential portions of Embodiment 6 of the method for producing a hologram lens of the present invention.

FIG. 11 is a schematic view of the essential portions of Embodiment 7 of the method for producing a hologram lens of the present invention.

FIG. 12 is a schematic view of a main part of Example 8 of a display device using the hologram lens of the present invention.

FIG. 13 is a schematic view of a main part of a display device using a conventional hologram lens.

[Explanation of symbols]

 1 Virtual stop surface (pupil) 2, 17, 211 Substrate 3 Hologram lens 4 Light flux 5 Image plane (image information) 6 Image display 7 Lamp house 8 Light source 31, 32, 33 Element hologram 11, 201 Laser light source 13a, 13b Collimator Lens system 18,212 Photosensitive material 16,20,204,205 Mirror 61 Liquid crystal display element 216 Computer hologram 219 Cylindrical lens 209,214 Collimator lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoko Yoshinaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsumi Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Tadashi Kaneko 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Susumu Matsumura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. An off-axis type hologram lens, wherein the hologram lens is divided into a plurality of element holograms, and each element hologram has a diaphragm that is virtually set on a surface of the hologram lens at a predetermined angle. An off-axis type hologram lens, which has a size when projected and is arranged so that the element holograms do not overlap each other. 2. An off-axis type holographic lens, wherein the holographic lens is divided into a plurality of element holograms, and each element hologram has a virtually set diaphragm at a point on a predetermined plane or curved surface. The off-axis is characterized in that it has a size when it is projected at a predetermined angle with a convergent light beam that converges and that the element holograms are arranged so as not to overlap each other.
An s-type hologram lens. 3. The hologram lens according to claim 1, wherein the hologram lens is a volume phase hologram. 4. A light beam based on image information from an image display is diffracted in a predetermined direction through an off-axis type hologram lens composed of a plurality of element holograms to obtain the image information and an image behind the hologram lens. When observing in the same field of view by spatially superimposing information on each other, each element hologram has a size when the diaphragm set virtually is projected onto the hologram lens surface at a predetermined angle, and A display device in which element holograms are arranged so that they do not overlap each other. 5. A light beam based on image information from an image display is diffracted through an off-axis type hologram lens composed of a plurality of element holograms, and the image information and the image information behind the hologram lens are separated. When observing in the same field of view by superimposing in space, each element hologram is projected at a predetermined angle with a converging light flux that converges a virtually set diaphragm to a point on a predetermined plane or curved surface. A display device having a size and arranged so that the element holograms do not overlap each other. 6. The display device according to claim 4, wherein the hologram lens is a volume phase hologram. 7. An object light optical system for generating the object light when incident light and reference light are made incident on the recording medium from different directions to form interference fringes on the recording medium to produce a hologram. A method for producing a hologram, characterized in that a cylindrical lens and a computer generated hologram are provided in at least one optical system of the reference light optical system for generating the reference light. 8. A light beam passing through an optical system including a cylindrical lens and a computer generated hologram and a light beam of a convergent spherical wave or a divergent spherical wave are made incident on a recording medium from different directions,
A method for producing a hologram, characterized in that interference fringes are formed on the recording medium to produce a hologram. 9. A method for producing a hologram, wherein a plurality of element holograms produced by the method according to claim 7 or 8 are arranged on a plane to produce a hologram. 10. The computer generated hologram is off-ax.
9. The method for producing a hologram according to claim 7, which is an is-type hologram. 11. A light flux based on image information from an image display is diffracted in a predetermined direction through a hologram lens,
When the image information and the image information behind the hologram lens are spatially overlapped and observed in the same field of view, the hologram lens generates an object light and an object light optical system and a reference light optical system that generates a reference light. A system in which at least one of the optical system is provided with a cylindrical lens and a computer generated hologram is made by making object light and reference light incident on the recording medium from different directions to form interference fringes on the recording medium. A display device characterized by being a volume phase hologram lens. 12. A light beam based on image information from an image display is diffracted through a hologram lens, and the image information and the image information behind the hologram lens are spatially superposed and observed in the same visual field. At this time, the hologram lens causes a light beam passing through an optical system including a cylindrical lens and a computer hologram and a light beam of a convergent spherical wave or a divergent spherical wave to enter a recording medium from different directions to form interference fringes on the recording medium. A display device, which is a volume phase hologram lens manufactured by the above method.