JPH08313845A - Optical element and optical device using the same - Google Patents

Abstract

PURPOSE: To provide an optical device using a spatial modulation element like the projection type liquid crystal display device capable of improving the uniformity of brightness of a light beam to be made incident on a spatial modulation element in addition to the improving of the utilization efficiency of the light from a light source. CONSTITUTION: An optical element 103 converts the incident light having a prescribed shape and a prescribed intensity distribution into the output light of a desired shape having a prescribed intensity distribution. The output light from the optical element 103 has the shape of either a square, a circle or an ellipse. Moreover, this optical device is also provided with an optical element 104 imparting directivity to the light beam shaped in the optical element 103 in addition to the optical element 103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device and an optical device, and more particularly to an optical device such as a projection type image display device and an optical information processing device using a spatial light modulator.

[0002]

2. Description of the Related Art A large-sized CRT has been developed as a large-screen image display device, but a projection-type display device has been attracting attention in order to meet the demand for further size increase. As the projection type display device, a projection type CRT display device that projects and displays an image displayed on a small-sized, high-precision and high-luminance CRT, and a projection type liquid crystal display device that projects and displays light modulated by a liquid crystal panel are available. However, the latter is particularly suitable for smaller size and lighter weight, and has the advantage that it can be easily introduced into general households.

FIG. 59 shows a typical configuration of a conventional projection type liquid crystal display device. In FIG. 59, the light emitted from the light source 1 with high brightness such as a metal halide lamp is reflected by the reflecting mirror 2 to become parallel light or focused light having directivity,
The liquid crystal panel 3 is illuminated. The light transmitted through the liquid crystal panel 3 is focused and projected on the screen 5 by the projection lens 4.

There are two types of projection methods, a rear projection type in which the image is projected from the rear side of the screen as seen by the observer and a front projection type in which the image is projected from the same side as the observer. Further, when displaying a color image, a single plate type using a liquid crystal panel with three color filters such as RGB (red, green, blue) and a three plate type using three liquid crystal panels for each color component is used. There is a method of. In a three-plate projection type liquid crystal display device, a dichroic mirror or the like is used to separate the light of a light source into three color components, and a method of projecting each color component using three projection lenses and a dichroic mirror or the like. There is also a method of synthesizing the color components again by using, and projecting using one projection lens.

In addition to the system using the transmitted light of the liquid crystal panel, a reflection type display device using the light reflected by the liquid crystal panel has been developed. Liquid crystal panel matrix methods include simple matrix, thin film transistor, thin film diode, etc., and liquid crystal operation modes such as TN and STN. Recently, polymer dispersed liquid crystal is used to control light scattering and transmission. And so on. Further, a display system using a device in which minute reflecting mirrors are arrayed formed by a process similar to the manufacturing process of a semiconductor integrated circuit has been developed.

FIG. 60 shows another configuration example of a conventional projection type liquid crystal display device. This device is disclosed in JP-A-6-175129. This device is designed to improve the focusing property of light from the light source, improve the light utilization efficiency, improve the contrast ratio and uniformity of the projected image, and reduce the size and robustness.

In FIG. 60, the light source 11 is arranged at the first focus position of the elliptical mirror 12. A convex cone-shaped prism 13 is arranged near the second focal position of the elliptical mirror 12. The light beam emitted from the light source 11 and condensed by the elliptical mirror 12 is collimated by the prism 13 in order to eliminate the dark spot due to the shadow of the light source 11 itself, and is collected in the central portion. The light beam that has passed through the prism 13 is projected on a screen (not shown) via a condenser lens 14, a transmission / scattering type display element 15, a second condenser lens 16, a diaphragm 17 and a projection lens 18. The light is aligned on the convex or concave surface of the prism, collimated by the condenser lens 14, and then incident on the transmissive liquid crystal display element 15.

However, in the projection type image display device using the spatial light modulator such as the liquid crystal panel described above, it is possible to display a large screen relatively easily, but on the other hand, sufficient brightness can be secured. There is a problem that it is difficult. Therefore, this device has problems that the room must be darkened and that power consumption is large because a high-output lamp is used as a light source. In particular, the ratio of the power of the light emitted from the light source to the screen, that is, the light utilization efficiency is only 1 to 2%, such as the illumination system, the color separation system, the spatial modulation system (liquid crystal panel), the color synthesis system. A major issue is to improve the light use efficiency in each part of the optical system from the projection lens to the screen.

Further, particularly in the configuration of FIG. 59, since the light source 1 itself has a shadow in the central portion in the intensity distribution of the light beam,
There is a problem of uneven brightness in that a dark shadow appears in the center of the screen on the screen 5. In order to solve this problem, in the configuration of FIG. 60, the convex pyramidal prism 13 collects light in the central portion to eliminate the shadow of the central portion. However, in the configuration of FIG. 60, since the bulky prism 13 is arranged near the focal point of the light beam coming from the elliptic mirror 12, the prism 1
There is a part where the power of light is locally concentrated in 3,
Shape distortion due to heat is likely to occur, which easily leads to destruction. Moreover, if the position of the prism 13 is moved away from the vicinity of the focal point in order to avoid this, the light utilization efficiency further decreases. In order to avoid this, the area of the entrance surface of the prism 13 must be made large, which increases the size of the prism 13 in the optical axis direction, which hinders the miniaturization of the entire apparatus.

[0010]

Another object of the present invention is to:
Provided is an optical device using a spatial modulation element such as a projection type liquid crystal display device capable of improving the utilization efficiency of light from a light source and improving the uniformity of brightness of a light beam incident on the spatial modulation element. To do.

[0011]

The present invention has taken the following means in order to solve the above problems.

The optical element of the present invention is characterized by converting incident light having a predetermined shape and a predetermined intensity distribution into output light having a desired shape having a predetermined intensity distribution. The output light has a shape of a square, a circle, or an ellipse.
Further, at least one of the phase transfer function representing the lead or lag of the phase to be given to the representative wavefront of the incident light or the shape of the optical element surface is set based on the optimization calculation.

According to the optical element of the present invention, the incident light having a predetermined (arbitrary) shape and a predetermined (arbitrary) intensity distribution can be converted to a predetermined intensity with a simple structure (that is, one optical element). A desired shape (for example, a rectangle, etc.) having a distribution (which will be referred to as “uniform” in the following because it basically has a uniform intensity distribution)
Ellipse).

A first optical device according to the present invention comprises a light source that emits a light beam having a predetermined beam shape and intensity distribution, and a rectangular shape having a uniform intensity distribution in which the beam shape of the incident light beam is It is characterized in that it is provided with a first optical element which is shaped into one of a circular shape and an elliptical shape, and a second optical element which imparts directivity to the shaped light beam that is incident.

In the present invention, the beam shape of the light beam is a sectional shape in a plane orthogonal to the optical axis of the light beam, and the intensity distribution means a distribution of light intensity in the same plane. To do.

According to one specific embodiment of the first optical device, the first optical element has an intensity of emitted light at a predetermined position when the first optical element is arranged in the optical path of a light beam having a predetermined beam shape and intensity distribution. The distribution shape is shaped so that the intensity relatively decreases at the central portion of the light beam and the intensity relatively increases at the peripheral portion, and has a substantially circular (or approximately elliptical) beam shape, for example. The intensity distribution of the emitted light at a predetermined position when arranged in the optical path of the light beam is approximately square (or approximately rectangular), or the diagonal width of the intensity distribution is wider than the width in the vertical and horizontal directions. Composed.

In the above structure, the preferred embodiment of the first optical element is as follows.

(1) The first optical element has a predetermined intensity distribution shape in which the central intensity is higher than the intensity in the peripheral portion and is substantially circular (or approximately elliptical), and the predetermined output light when placed in the incident optical path. The fluctuation of the intensity distribution at the position must be 40% or less within a predetermined rectangular (square or rectangular) area.

(2) The first optical element has a total intensity of emitted light when arranged in an incident optical path having a predetermined intensity distribution shape of which the central intensity is higher than the intensity of the peripheral portion and is substantially circular (or approximately elliptical). 70% or more is configured to be irradiated within a predetermined rectangular area.

(3) In the first optical element, the phase transfer function representing the phase given to the incident light depending on the incident position gives a linear function for giving a deflection, focusing of the entire beam, divergence, spherical aberration, etc. In addition to the axially symmetric function and the combination of 0 or 1 or a plurality of functions that give the focusing or divergence only in one direction like a cylindrical lens, a function having a fourth-order or higher-order component with respect to coordinates Be composed.

(4) The first optical element as described in (1) to (3) specifically realizes a reflecting mirror having a surface shape that realizes a predetermined phase transfer function, or a predetermined phase transfer function. A transmission type optical element having at least one of a surface shape and a refractive index distribution.

(5) When the first optical element has a surface shape that realizes a predetermined phase transfer function, the surface shape is defined by a boundary line where the height of the surface shape from a predetermined reference plane is constant. Being discontinuous, and being configured so that the surface shape is continuous in multiple areas separated by boundaries.

(6) The first optical element can also be constituted by a reflective or transmissive diffractive optical element that realizes a predetermined phase transfer function. This diffractive optical element
For example, it is formed by a blazed grating in which the intensity of the diffracted light is concentrated in the diffracting direction to be used by using the diffracted light of the second or higher order.

(7) The first optical element is arranged in the optical path of the incident light beam substantially perpendicular to the optical axis of the light beam, and a groove formed of a plurality of curved lines is formed on the surface thereof. A transparent substrate.

A preferred embodiment of the second optical element is as follows.

(1) The second optical element has a function of changing the optical path depending on the incident position of the incident light beam, and the shape of the light beam is shaped and the intensity distribution is made uniform by the first optical element. To give directivity to a light beam.

(2) In the second optical element as described above, the phase transfer function representing the phase imparted to the incident light depending on the incident position is a linear function for imparting deflection, focusing of the entire beam, divergence, and spherical surface. An axially symmetric function that gives aberrations, and
A function having a fourth-order or higher-order component with respect to coordinates other than a combination of 0 or 1 or a plurality of functions that impart focusing or divergence only in one direction like a cylindrical lens.

(3) The second optical element is a reflecting mirror having a surface shape that realizes a predetermined phase transfer function, or transmissive optics having at least one of a surface shape and a refractive index distribution that realizes a predetermined phase transfer function. Consist of elements. Here, the optical element having a surface shape that realizes a predetermined phase transfer function is specifically such that the surface shape is discontinuous at a boundary line where the height of the surface shape from a predetermined reference plane is constant. , The surface shape shall be continuous within the multiple areas separated by the boundary line.

(4) The second optical element can also be constituted by a reflective or transmissive diffractive optical element that realizes a predetermined phase transfer function. This diffractive optical element
For example, it is formed by a blazed grating in which the intensity of the diffracted light is concentrated in the diffracting direction to be used by using the diffracted light of the second or higher order.

In the above first optical device, the incident light beam is passed through the first optical element to shape the beam shape into a rectangular shape or an elliptical shape, and the light whose directivity is disturbed as the beam shape is shaped. Directivity is given to the beam by the second optical element. A light beam from a light source, which usually has a circular beam shape and a non-uniform light intensity distribution, is passed through the first and second optical elements, so that a spatial modulation element such as a generally rectangular liquid crystal panel can be used. Therefore, it is possible to irradiate a light beam whose beam shape is close to that of the spatial light modulator and whose intensity distribution is uniform, and it is possible to improve the light utilization efficiency even when using the same light source as before The spatial modulation element can be illuminated with sufficient brightness.
In addition, the brightness and the uniformity of brightness comparable to the conventional one can be achieved under the power consumption lower than the conventional one. Therefore, if the first optical device is applied to the projection type liquid crystal display device, it is possible to improve performance and reduce power consumption.

A second optical device according to the present invention is disposed in the optical path of a light beam having a predetermined intensity distribution, and has a transparent surface having a groove having a concentric circular surface or a spiral surface with a constant angle. A first optical element formed of a light-transmitting substrate, and arranged in an optical path of a light beam passing through the first optical element,
A second optical element that imparts directivity to the incident light beam.

In the second optical device, the intensity distribution of the incident light beam is controlled by the first optical element which is formed by forming grooves having slopes at a constant angle on the translucent substrate in a concentric or spiral shape. The light beam that has been made uniform and has passed through the first optical element is given directivity and is incident on the spatial light modulator.
That is, since the first optical element produces the effect of a prism that refracts light rays by the groove formed on the surface of the substrate, even if the light beam from the light source system that is the incident light beam has a dark spot near the center, By moving the partial light to the central part, the dark spots disappear in the emitted light beam, and the light intensity distribution can be made uniform.

Further, the first optical element is different from a bulk prism that refracts light due to its three-dimensional shape, and is made of a light-transmissive substrate having grooves formed on its surface, and can be made very thin. Therefore, the heat dissipation is very good. Therefore, a powerful cooling device is not required and cooling is easy.
Further, even if the first optical element is provided at the focal point of the reflecting mirror existing in the light source system, that is, near the focusing position of the incident light beam, there is no risk of destruction due to heat, so that it is compared with the case where a bulk prism is used. Then, the light utilization efficiency is improved. In addition,
The two-element method (a method in which the first element has a light beam of a desired shape that has a uniform intensity distribution and the second element has directivity) allows the optical element to be placed away from the vicinity of the focal point, which causes thermal destruction. There is no fear of. Furthermore, since the thickness of the first optical element may be the same even if the diameter of the first optical element is increased, a large diameter and compact size can be manufactured, which contributes to downsizing of the optical device.

Further, in the second optical device, the light beam that has passed through the first optical element is passed through the second optical element to give directivity, whereby the light utilization efficiency is further improved.

According to the third optical device of the present invention, in the optical path of the light beam having a predetermined beam shape and intensity distribution, the phase transfer function (the phase shifts as the phase shifts toward the outside on the plane perpendicular to the optical axis of the light beam). A first optical element having a characteristic (for example, a refractive index distribution) in which the amount of delay decreases or increases linearly is arranged, and directivity is imparted to the light beam in the optical path of the light beam that has passed through the first optical element. The second optical element is arranged, and the light beam is guided to the spatial modulation element via the first and second optical elements.

In the third optical device, the phase transfer function linearly decreases or increases as the incident light beam goes outward on the plane perpendicular to the optical axis.
The intensity distribution of the light beam is made uniform by the optical element, and the light beam that has passed through the first optical element is incident on the spatial light modulation element with directivity. That is, since the first optical element has the effect of a prism due to the change of the phase transfer function, even if the incident light beam has a dark spot near the center, it does not affect the peripheral area as in the first optical element in the second optical device. By moving the light in the center to the center, the dark spots disappear in the emitted light beam, and the effect of making the light intensity distribution uniform is obtained, and it is made extremely thin by the translucent substrate with a changed phase transfer function. Because it is possible, the heat dissipation is very good.

Therefore, according to the third optical device, the first
Even if an optical element is provided in the focal point of a reflecting mirror existing in the light source system, that is, near the focus position of the incident light beam, there is no risk of damage due to heat, so use of light is greater than when a bulk prism is used. Efficiency is improved. Furthermore, since the thickness of the first optical element may be the same even if the diameter of the first optical element is increased, a large diameter and compact size can be manufactured, which contributes to downsizing of the optical device. Further, like the second optical device, in the case of the two-lens system, the optical element can be arranged at a position deviated from the focus position, so that there is no risk of thermal destruction of the optical element.

Further, also in the third optical device, the light beam passing through the first optical element is passed through the second optical element to give directivity, whereby the light utilization efficiency is further improved.

The fourth optical device according to the present invention is arranged in the vicinity of the focusing point in the optical path of the converging light beam having a predetermined intensity distribution, and is formed with concentric or spiral grooves having slopes with a constant angle. An optical element having a transparent substrate is provided.

In the fourth optical device, an optical element similar to the first optical element in the second optical device is arranged near the focusing point of the converging light beam and in front of the focusing point in the traveling direction of the light beam. Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

The fifth optical device according to the present invention is arranged near the focusing point in the optical path of the converging light beam having a predetermined intensity distribution and in front of the focusing point in the traveling direction of the light beam. It is characterized by comprising an optical element having a characteristic that the phase transfer function linearly decreases from the optical axis toward the outside on a plane perpendicular to the axis.

Also in the fifth optical device, by disposing an optical element similar to the first optical element in the third optical device near the focusing point of the converging light beam and in front of the focusing point in the traveling direction of the light beam, Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

The sixth optical device according to the present invention is arranged near the focusing point in the optical path of the converging light beam having a predetermined intensity distribution and behind the focusing point in the traveling direction of the light beam. It is characterized by comprising an optical element having a characteristic that a phase transfer function linearly increases from the optical axis toward the outside on a plane perpendicular to the axis.

Also in the sixth optical device, by disposing an optical element similar to the first optical element in the third optical device near the focusing point of the converging light beam and behind the focusing point in the traveling direction of the light beam, Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

As described above, according to the present invention, the power of the light beam emitted from the light source is effectively converted into a light beam having a desired shape and a desired intensity distribution with a high efficiency while ensuring the directivity. Can be shaped. This makes it possible to illuminate the liquid crystal panel with a rectangular or circular uniform light beam, which makes it possible to realize a display device with higher image utilization efficiency and better brightness than the conventional one, and with good image quality. In other words, it is possible to solve the disadvantage that the periphery of the screen is dark in the conventional device, and further realize a liquid crystal projection display device having a brighter screen than the conventional one with the same power consumption as the conventional one.
Alternatively, a screen having the same brightness as that of the related art can be realized by a device having lower power consumption than that of the related art.

The present invention is effective not only for white light but also for laser light, and provides a means for converting a circular light beam into a uniform rectangular beam. Therefore, the present invention can be applied not only to the display device but also to a wide field that is required to efficiently illuminate a rectangular area. For example, the present invention can be applied to a calculation using light, an information processing device, an image processing device, and the like. Even in this case, similarly to the display device, reduction in power consumption or improvement in performance brought about by improvement in irradiation intensity can be obtained as an effect.

Further, according to the present invention, it is possible to realize the elimination of dark spots for a light beam having a dark spot at the center in the light intensity distribution of the beam cross section by using an optical element, and improve the uniformity of the light beam. can do. Moreover, the optical element of the present invention is less likely to be damaged by heat than a bulk-shaped conical lens, and has a large degree of freedom in design, such as being able to make a large and thin lens. It has the advantage that an optical device can be realized.

The optical element of the present invention is characterized in that, in the above-mentioned optical element, the output light is brighter in the central portion than in the peripheral portion. Further, it has either a concentric circular groove or a spiral groove, and the groove has a light intensity distribution Li (ri) on the incident surface of the optical element of the light incident on the optical element, and a light intensity on a desired surface. Let the distribution be Lo (ro), and if Ri> rimax, Li (ri) = 0, and if ro> romax, Lo (r
o) = 0,

(Equation 3)

The inclination angle of the slope is set so that

Since the optical element according to the present invention has fine grooves formed on the surface thereof, light rays are refracted by the grooves and the effect of a prism is produced. Thereby, even if the light coming from the light source has a dark spot near the center, the light in the peripheral portion can be moved to the central portion to eliminate the dark spot. In addition, the optical element according to the present invention does not need to have a three-dimensional shape and is made extremely thin, as compared with a bulk prism that refracts by a three-dimensional shape, because the optical element according to the present invention refracts by processing applied to the surface. It is possible to dissipate heat very well. Further, even if the diameter is increased, the thickness may be the same, so that a large-diameter and compact one can be manufactured.

Since the inclination angle of the inclined surface of the groove is set for each radius with the optical axis as the center, the light intensity distribution in the radial direction of the optical element can be freely controlled. With this, the central bright spot can be erased. Further, since the groove slope angle of the second optical element which is incident after the desired light intensity distribution is obtained is set for each radius, the directivity of the light beam in the radial direction can be freely controlled.

An optical device using the optical element of the present invention is
It is characterized by comprising at least one first optical element for converting incident light having a predetermined shape and a predetermined intensity distribution into output light having a desired shape having a uniform intensity distribution.
The output light is characterized in that the central part is brighter than the peripheral part. Further, the first optical element has a concentric circular or spiral groove, and the groove has a light intensity distribution Li (ri) on the incident surface of the optical element of the light incident on the optical element.
), The light intensity distribution on the desired surface is Lo (ro), and ri
When Li (ri) = 0 when> rimax and Lo (ro) = 0 when ro> romax,

[Equation 4]

The inclination angle of the slope is set so that Here, ri: position from the optical axis of the incident light beam, rimax: position farthest from the optical axis of the incident surface of the optical element, ro: on the desired surface of the output light beam corresponding to the incident light beam Position from optical axis, romax: The position farthest from the optical axis on the desired surface where the output light beam can reach.

In the above optical device, an inclined surface having an angle that changes according to the distance from the central axis is provided so as to impart a predetermined directivity to the light of the desired shape having the uniform intensity distribution. It is characterized by further comprising at least one second optical element having either concentric or spiral grooves.

Further, the liquid crystal projection type display device of the present invention has a light source which emits a light beam having a constant beam shape and intensity distribution, and a beam shape of the incident light beam which has a uniform intensity distribution. At least 1 to shape to desired shape
One first optical element, a second optical element that imparts directivity to the shaped light beam that is incident, and a light beam that has been imparted with the directivity are incident on the first optical element to display a desired image. It is characterized by comprising a liquid crystal panel which allows light to pass therethrough and a screen which displays the light passing through the liquid crystal panel as an image.

An optical device to which the optical element of the present invention is applied is
By using the large-diameter and compact optical element as described above, it becomes compact and high-performance.

[0057]

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

(First Embodiment) FIG. 1 is a view showing the arrangement of an optical system of a projection type liquid crystal display device according to the first embodiment of the present invention. In the figure, the light (white light) emitted from a light source 101 such as a metal halide lamp is reflected by a reflecting mirror 102 having a paraboloid of revolution, and becomes a light beam collimated substantially in parallel.

This light beam is the first optical element 1 for shaping the beam shape and uniformizing the light intensity distribution according to the present invention.
03, and the second optical element 104 that imparts directivity, are sequentially converted into a light beam having a rectangular beam shape and a uniform intensity distribution and good directivity. The light beams that have passed through the first and second optical elements 103 and 104 include a dichroic mirror 105 that transmits only light having a wavelength near red, and a light having a wavelength near green and light having a wavelength near blue. Is separated into three color components by the dichroic mirror 106 that reflects light, and is also modulated by the liquid crystal panels 108 to 110 that also display images corresponding to the respective wavelength components using the cold mirror 107.

The lights modulated by the liquid crystal panels 108 to 110 are combined by the cold mirror 111 and the dichroic mirrors 112 and 113, and then projected on the screen 115 by the projection lens 114 to display a color image on the screen 115. To be done. Screen 11
When a transmissive type is used, 5 is incorporated in a device integrated with the projection device, but when a reflective type is used, it may be configured as a device integrated with the projection device, or an independent single screen. The projection device for use may include a projection lens as a single unit, and the present invention is not limited to these configurations, and any case is included in the present invention.

Further, a field lens may be inserted immediately after the liquid crystal panel in order to improve the utilization efficiency of light and downsize the aperture of the projection lens. Further, in order to reduce the size and weight of the device and to reduce the cost, a single plate type configuration using a single liquid crystal panel equipped with a color filter may be used without using three panels, and the number of panels is limited. Not done. With the single-plate configuration, there is no need for dichroic mirrors or cold mirrors for color separation or color composition,
The feature is that the device can be configured with a small number of parts. Further, although a transmissive liquid crystal panel is used as the spatial light modulator, it may be of a reflective type or may be an array of micromirrors instead of the liquid crystal, and is limited to the system of the spatial light modulator. Not a thing.

Although not limited to the projection type, since the liquid crystal display device uses a rectangular liquid crystal panel, the first optical element 103 typically shapes the beam shape into a rectangular shape.

FIG. 2 shows a first optical element 103 which shapes the beam shape of an incident light beam and makes the intensity distribution uniform,
It is a figure showing various examples of arrangement of the 2nd optical element 104 which gives directivity.

FIG. 2A is configured as a transmission type optical element which imparts a deflection to change the traveling direction of the light beam as well as shaping the beam shape and uniformizing the intensity distribution to the light beam incident in parallel. A first optical element 103 and a second optical element 104 configured as a transmissive optical element that imparts a deflection together with directivity are arranged. This is the same as the arrangement of the first and second optical elements 103 and 104 shown in FIG.

The first optical element 103 is the second optical element 104.
The beam shape and the intensity distribution of the light beam at the position are designed to have a predetermined shape and distribution. Meanwhile, the second
The optical element 104 is designed so that the incident light is output as a light beam with good directivity. In this example, the traveling directions of the light incident on the optical element 103 and the light emitted from the optical element 104 are parallel, but they do not necessarily have to be parallel. In addition, the first and second optical elements 103, 1
Since 04 has a deflection effect, the directions of incident light and emitted light are different. In this way, when the first and second optical elements 103 and 104 are composed of diffractive elements,
Since the lattice pattern has a striped shape, the device is easy to design and manufacture.

FIGS. 2B to 2F show the first and second parts.
In another arrangement example of the optical elements 103 and 104, the first optical element 103 has a function of shaping the beam shape and uniformizing the intensity distribution, and the second optical element 104 has a function of giving directivity. The points are the same as in FIG.

Of these, FIG. 2B shows a mode in which the first and second optical elements 103 and 104 do not have a deflecting action and allow light to go straight, and FIG. 2C shows the first and second optical elements. 10
3 and 104 each have a deflecting action to refract the optical axis. FIG. 2D shows the first and second optical elements 1.
An arrangement in which reflective elements are combined as 03 and 104,
2E shows the optical element 103 as a transmissive element and the optical element 104 as a reflective element, and FIG. 2F shows the optical element 103 as a reflective element and the optical element 104 as a transmissive element. Is an example.

In the present invention, the first and second optical elements 103,
The high degree of freedom with respect to the arrangement of 104 is also one of the features, and the present invention is not limited to the arrangement shown in FIG. 2, and an optical device in which an optical element having a similar function is arranged is included in the present invention. Further, according to the configuration of the entire apparatus, the first and second optical elements 10 are adjusted in accordance with the easiness of operation adjustment and the like, the ease of manufacturing, and the lightness of demand for downsizing of the apparatus.
The arrangement of 3, 104 can be selected.

FIG. 3 is a diagram showing another example of the arrangement of the first optical element 103 for shaping the beam shape and uniforming the intensity distribution, and the second optical element 104 for giving directivity. In these examples, the incident light of the first optical element 103 is parallel light in FIG. 2, whereas the incident light is focused light, and the arrangement example of FIG. 3 corresponds to that of FIG. It corresponds. As still another example, the incident light of the first optical element 103 may be divergent light. The specific form of the optical element 103 differs from that of FIG. 2 depending on the state of these incident lights.

In the optical device using the arrangement as shown in FIG. 3, the light emitted from the light source is reflected by the lens, the reflecting mirror, etc.
Instead of being collimated into collimated light, it is focused or diverged. For example, when the shape of the reflecting mirror is a spheroid and the light source is located at one focal point, the reflected light is focused toward the other focal point. If the optical element is placed inside this focal point, the incident light is focused light, and if it is placed outside, it is divergent light. In addition, the divergent light from the light source may be used as it is without using a lens, a reflecting mirror, or the like.

Since the diameter of the beam can be easily expanded or reduced by using the focused light or the divergent light as described above,
The spatial light modulator used and the light source can be freely configured to be convenient. Since the functions of expanding and contracting the beam diameter can be realized by the first optical element 103 and the second optical element 104, at least one of the optical elements can have this function.
The present invention is not limited by this choice.

FIG. 4 is a diagram showing still another example of the arrangement of the first optical element 103 for shaping the beam shape and uniformizing the intensity distribution, and the second optical element 104 for giving directivity.
In these examples, the emitted light of the second optical element 104 is parallel light in FIGS. 2 and 3, but it is the case of focused light, and FIG. 3 corresponds to FIG. 2 or FIG. 3, respectively. are doing. As yet another example, the light emitted from the second optical element 104 may be divergent light. Depending on the state of these emitted light,
The specific form of the optical element 104 differs from the case of FIG. 2 or FIG. As for the incident light of the first optical element 103, the case where focused light is incident is shown, but it may be divergent light or parallel light.

The light emitted from the second optical element 104 reaches a spatial light modulator such as a liquid crystal panel (not shown). The spatial light modulator exhibits the best modulation characteristics when light is incident on the incident surface at a specified angle (for example, vertical), but sufficient characteristics are realized if the incident angle is within the specified tolerance range. it can. The degree of focusing or divergence of the light emitted from the optical element 104 must be set within a predetermined allowable range of the incident angle of the spatial light modulation element.

The advantage of making the light emitted from the optical element 104 into a focused or divergent state is that the transmission of the light to the optical system that follows it becomes effective. That is, FIG.
In the projection type liquid crystal display device shown in FIG.
A large amount of light that has exited through 110 reaches the screen 115 via the projection lens 114, so that a bright display can be obtained. For that purpose, a light flux that is slightly focused is used for the liquid crystal panel 1.
It is better to irradiate 08 to 110. There is also a method of using a field lens immediately after the liquid crystal panel, but when the emitted light of the optical element 104 is focused as in the example shown in FIG.
Since the optical component for focusing can be omitted, the optical device can be realized more simply and inexpensively.

(Second Embodiment) A projection type liquid crystal display device according to a second embodiment of the present invention will be described. In this embodiment, the configuration of the optical system is almost the same as that of the first embodiment,
Using only the (first) optical element 103 that shapes the beam shape of the incident light beam and makes the intensity distribution uniform,
The apparatus is configured by a method in which the (second) optical element 104 that imparts the directivity used in the embodiment is omitted.

FIG. 5 is a diagram showing the relationship between the liquid crystal panel 108 and the optical element 103 that shapes the beam shape and uniformizes the intensity distribution in the projection type liquid crystal display device according to this embodiment. In the present embodiment, in the case of a single plate type, the liquid crystal panel 108 having a color filter is used. In the case of the three-plate type, the same color separation and color combination as in FIG. 1 are performed using a dichroic mirror, a cold mirror, and three liquid crystal panels 108 to 110, which are not shown, as in FIG. In any case, since the relationship between the optical element 103 and the liquid crystal panel 108 is the same, a single liquid crystal panel 108 will be representatively described in order to facilitate understanding of the gist of the invention.

In the first embodiment, the first optical element 103 has a predetermined position at a relatively close position where the second optical element 104 for giving directivity is set, and the beam shape and the intensity distribution at this position have a predetermined shape. And was designed to have a distribution. On the other hand, the optical element 10 in the present embodiment
3 is designed so that a relatively distant position where the liquid crystal panel 108 is installed is a predetermined position, and the beam shape and the intensity distribution at this position have a predetermined shape and distribution. For this reason, the liquid crystal panel 108 is efficiently and uniformly irradiated with light, but the directivity is not always ensured. However, from the optical element 103 to the liquid crystal panel 1
Since the distance to 08 is relatively large, the liquid crystal panel 108
The light beam incident on the beam has some directivity. Therefore, as compared with the size of the allowable range in which the characteristics of the liquid crystal panel 108 as a spatial light modulator can be sufficiently secured, sufficient illumination characteristics can be realized and good display characteristics can be obtained.

According to the second embodiment, the directivity of the light beam with which the liquid crystal panel is irradiated is slightly inferior to the method of using the second optical element 104 which imparts the directivity as in the previous embodiment. However, since it is possible to avoid the loss of the light amount due to the second optical element 104 and the number of parts can be reduced, it is advantageous in reducing the size and weight of the device and reducing the cost.

(Third Embodiment) A specific method of implementing the first optical element for shaping the beam shape and uniformizing the intensity distribution and the second optical element for imparting directivity according to the present invention (design method). ) Will be described. Since the first and second optical elements are both realized by a similar design method and a similar configuration, both will be described together.

Calculations for optimizing the phase transfer function (or the shape of the element surface, etc.) representing the lead or lag of the phase to be given to the representative wavefront of the incident light in both the first and second optical elements, etc. Then, an optical element that realizes this is manufactured. The cause of the difference between the optical element that converts the intensity distribution and the optical element that imparts directivity is the difference in the specific setting target in the optimization calculation when determining the phase transfer function or the shape of the element surface. Results from However, in any case, the phase transfer function is a characteristic function form in the present invention, and specifically, a linear function that imparts a deflection, an axisymmetric function that imparts focusing, divergence, spherical aberration, etc. of the entire beam. , And a function having a fourth or higher order component with respect to coordinates, in addition to a combination of 0 or 1 or a plurality of functions that give a focusing or divergence only in one direction like a cylindrical lens.

FIG. 6 is a diagram schematically showing the principle of the case where the optical element according to the present embodiment is composed of the transmissive optical element 201. In FIG. 6, a transmissive optical element 201 is an optical element that shapes the beam shape of an incident light beam and uniformizes the intensity distribution, or an optical element that imparts directivity. The incident light 202 has an undulating optical element 2
In the process of passing through 01, a phase advance or delay occurs, and the wavefront of the emitted light 203 becomes a curved surface. This emitted light 203 is
Energy is propagated in the direction normal to the wavefront.

Therefore, by designing the optical element 201 such that the intensity distribution of the emitted light 203 at a predetermined position falls within a predetermined range (or becomes uniform within a predetermined range), the incident light beam It is possible to design an optical element that shapes the beam shape and uniformizes the intensity distribution. On the contrary, by designing the optical element 201 so that the wavefront of the emitted light approaches a flat surface with respect to the incident light when placed at that position, the optical element that imparts directivity can be designed.

The actual incident light is not always coherent light and is an aggregate of light rays having various wave number vectors. Good operating characteristics can be secured by designing in a typical traveling direction.

When such an optical element is constructed as a transmissive optical element, one method is to process the surface of an optical material having a uniform refractive index into a predetermined shape as shown in FIG. However, there is also a method in which the surface of the element is made flat and a refractive index distribution is generated inside the element to realize an optical element having a similar function. It is also possible to form undulations on both sides, or to realize an optical element using both the refractive index distribution and the surface shape. In either case, the spatial distribution of the phase imparted when the incident light and the emitted light are compared contributes to the conversion of the intensity distribution or the impartation of directivity.

FIG. 7 is a diagram schematically showing the principle of the case where the optical element according to the present embodiment is composed of the reflection type optical element 211, and the operation by the action of the surface shape (undulation) is shown in FIG.
Is the same as in the example. Although not shown in the figure, it is also possible to form the flat mirror with the element as shown in FIG. In this case, since the reciprocating optical path is used in the optical element, the undulation of the surface may be smaller than that in the case of FIG.

FIG. 8 is a diagram showing an example of a case where the optical element according to this embodiment is realized by a transmissive diffractive optical element 221. In this case, if the configuration is such that the optical axis is deflected, the pattern of the diffraction grating may be striped, which may facilitate the element fabrication.

FIG. 9 is a diagram showing an example of a case where the optical element according to the present embodiment is realized by a reflection type diffractive optical element 231.

As shown in FIG. 6 to FIG. 9 described above, if the element causes a predetermined wavefront conversion, various realizing means can be considered.

In the examples of FIGS. 6 to 9, the optical element is realized as a single element, but a reflecting mirror, a prism, a lens,
It can also be realized by combining with other optical elements such as a cylindrical lens. On the contrary, both sides of the thick glass element can be configured to function as an optical element that converts the intensity distribution or an optical element that imparts directivity. These appear as different optical elements in appearance, but the gist thereof is the same and all are included in the present invention.

Next, an example of a specific design method of the first optical element for converting the intensity distribution and the second optical element for imparting directivity according to the present embodiment will be described. Both the method itself and the idea can be applied to other arrangement examples of the optical element.

FIG. 10 is a diagram showing an example of a specific arrangement of elements in the optical device according to the present embodiment. Figure 10
At, the light emitted from a light source 101 such as a metal halide lamp is reflected by a reflecting mirror 102 having a paraboloid of revolution, and becomes a light beam collimated substantially in parallel. This light beam is emitted by the first optical element 103 and the second optical element 104.
Are designed to be converted into a light beam having a light intensity distribution having a substantially uniform and rectangular cross-sectional shape by sequentially passing through. FIG. 10 also shows the liquid crystal panel 108, the field lens 116, and the screen 115 in addition to these, but since they are not the characteristic parts of the present invention, description thereof will be omitted.

The design of the first optical element 103 will be described. Among the light rays that pass through the first optical element 103, some representative light rays are selected as sample light rays. Figure 11
FIG. 6 is a diagram showing the positions of sample rays on the surface of the first optical element 103. In this example, 72 rays are used. The radius of the reflecting mirror 102 is 45 mm, and the region where the light does not enter due to the shadow of the electrode of the metal halide lamp that is the light source 101 exists in the center with a radius of 5 mm.
Although the sample is taken on a concentric circle within the radius of 5 mm to 45 mm, in the present embodiment, a bilaterally symmetric system is assumed, so the sample is set only in the right half.

FIG. 12 is a diagram showing a point on the surface of the second optical element 104 that the sample light beam should reach, that is, a target reaching point. The diagonal line length is 3 × 25.4 mm (so-called 3 inch size). Assuming a liquid crystal panel with a ratio of 3: 4,
These target reaching points are arranged in a rectangle of the same shape and size as this liquid crystal panel. The intensity distribution of the incident light is assumed to be Gaussian, and 1 / e ² half width w and the reflection mirror 10 are used.
The radius R of 2 has a relationship of R / W = 0.7. Considering that the intensity distribution of the incident light is Gaussian, the intensity distribution after conversion is arranged so as to be uniform over the entire screen. In the design, the phase transfer function of the second optical element 104 is optimized so that the actual reaching point approaches the target reaching point.

Although the distance between the first optical element 103 and the second optical element 104 is 200 mm in this embodiment, it may be shorter or longer, and the optical element can be easily machined and the device size can be increased. It may be set in consideration of the above.

The phase transfer function φ (x, y) is a function of the coordinates x, y on the optical element surface, and the phase shift amount added at that position is 2πφ (x, y) / λ (λ: incident light The wavelength is defined as a function. Definitions that are multiplied by different coefficients may be used depending on the literature, but if the same definition is used consistently, there is no substantial difference in either case. The z-axis is taken in the direction perpendicular to the surface of the optical element and used in the following description.

The direction vector of the light incident on the points x and y of the optical element characterized by the phase transfer function φ (x, y) is (nx, ny, nz). However, the length of the direction vector is 1. At this time, when the direction vector of the emitted light is (nx ', ny', nz '), the components nx', ny 'are given by the following equations.

Nx '= nx + 〓φ (x, y) / 〓x ny' = ny + 〓φ (x, y) / 〓x Further, nz 'is obtained from the condition that the length of the direction vector is 1. That is, when a sample ray group incident on the element whose phase transfer function is represented by φ (x, y) is given, an outgoing ray is obtained for each ray and an arrival point is obtained.

In order to determine the phase transfer function φ (x, y) required to realize the desired characteristic, first, the function form φ (x, y, C1, ..., CM) including many parameters C1 to CM is used.
), C1 ~ that best achieves the desired characteristics.
Decide on CM. Specifically, with respect to the incident position (xi, yi) of the sample light beam, the position (xi ', yi') of the target reaching point and the actual reaching point (xi ", yi")
The square of the distance to and is calculated, and the total sum over all the sample rays, that is, S = Σ {(xi′−xi ″) ² + (yi′−yi
″) ² } (i is a subscript representing each of the sample rays, and is assumed to be the sum of all the sample rays). Find the combination of the parameters C1 to CM that minimizes this calculation. Is basically the same as the above, and a normal least squares method algorithm may be followed.

In this embodiment, the function form is used in which the coordinates are converted from rectangular coordinates to polar coordinates and expressed as a function of r and θ. The relationship with Cartesian coordinates is x = r × sin θ, y = r ×
given by cos θ. By doing so, it is easy to deal with cases such as when there is a singular point in the center, and because it is possible to consider the rotational symmetry around the optical axis with good visibility, light with intensity distribution around the optical axis can be considered. It is often convenient to deal with beams. The concrete function form is shown in the following equation. It should be noted that this expression includes only cos and is a function form that always becomes a symmetrical function.

[0100]

(Equation 5)

Regarding the design of the second optical element 104, the points on the first optical element 103 and the points on the second optical element 104, which are obtained by tracing the sample beam according to the result of designing the first optical element 103, are selected. Use the correspondence function to design the ray by looking in the opposite direction. That is, for the light ray that has passed through the point on the second optical element 104, the second optical element 104 is set so that the corresponding point on the first optical element 103 becomes the target reaching point.
Should be designed.

In the design of this embodiment, the function form shown in Expression 2 is used as in the first optical element 103, but other function forms may be used based on consideration of the optical system. The parameter values obtained as a result of optimization for each element are shown in FIG. 14 and 15 show the profile of the phase transfer function obtained for the first optical element 103 and the second optical element 104.

When the optical element for realizing φ (x, y) thus obtained is constructed as a reflection type optical element, a ray passing through x and y is equal to φ (x, y). Since the phase may be delayed, a curved mirror may be configured so that the depth at the point of coordinates (x, y) is φ (x, y) / 2 for vertical incidence. If this similar optical element is used for light incident at an angle α,
The depth of the point with coordinates (x, y) is φ (x, y) / (2 × c
osα) may be configured as a curved mirror. In this case,
4. An optical element having a shape obtained by appropriately multiplying the shape of FIG.

When the optical element that realizes the phase transfer function φ (x, y) is constructed as a refractive optical element,
Since the phase of the ray passing through x and y is delayed by the optical path length of φ (x, y), the thickness of the point of coordinates (x, y) is required if a material having a uniform refractive index n is used. Increase / decrease of φ
A lens having a curved surface such that (x, y) / (n-1) may be formed. In this case, the optical element has a shape obtained by appropriately multiplying the shapes shown in FIGS. 14 and 15 with respect to the undulation direction. If the thickness d is constant and the refractive index distribution is used, a lens having a refractive index of φ (x, y) / d at a point of coordinates (x, y) may be formed.

If the first and second optical elements 103 and 104 are constructed as reflective optical elements or refractive optical elements having a uniform refractive index, the undulation becomes large, so that it is not always advantageous in mass production. Forming the refractive index distribution is not always advantageous in mass production.

On the other hand, the first and second optical elements 10
It is often the case that mass production is facilitated by configuring 3, 104 as diffractive optical elements. The design in that case is shown below.
The optical element that realizes the phase transfer function φ (x, y) for the light of wavelength λ 0 may be a diffractive optical element having a pattern in which contour lines with an interval of λ 0 are drawn with respect to φ (x, y).

First optical element 103 and second optical element 10
16, the contour lines of the phase transfer function obtained for 4 are shown in FIG.
It shows in FIG. Λ0 = 630 as a typical red wavelength
Since the pitch is too small when plotting contour lines at nm intervals, FIGS. 16 and 17 show thinned contour lines for every 100 lines. This is like a Fresnel lens, but since it transforms a circle into a horizontally long quadrangle, it is a flat curve group that is crushed slightly up and down. Further, since the distribution needs to extend in the diagonal direction from the direction of the vertical line, the lattice spacing is wide in that direction, and the shape is a closed curve having a shape similar to a shape with rounded corners of a rectangle. An example of how the features appear when this shape is coaxial and a circle is converted into a quadrangle is shown. However, in the case of the present embodiment, since the size of the liquid crystal panel is smaller than the cross-sectional area of the incident light, the first optical element has a slightly converging function as a whole.
On the other hand, when it has a divergent function, the lattice spacing is narrow in the direction of the diagonal line and the closed curve is close to a diamond.

When the optical elements simultaneously perform the deflection function, the pattern basically has a striped pattern. That is, the pattern actually formed by the arrangement used shows various aspects. However, focusing on the phase transfer function, in any case, except for the component representing the deflection function and the component representing the lens function that controls the overall focusing and divergence, the phase transfer function has a fourth-order or higher-order component related to coordinates of almost the same shape. Shows a characteristic function form,
All variations having similar components are included in the invention.
However, when functions such as deflection are combined, not only is a linear function for adding deflection simply added to the phase transfer function in the case of straight travel, but also to correct incidental aberrations. In addition, the intensity distribution conversion with higher accuracy can be realized by adding some correction components.

In order to confirm the effect of this embodiment, a simulation by ray tracing was performed.

FIG. 18 shows the first simulation.
FIG. 3 is a diagram showing the position of a light ray that has entered the optical element 103.
It can be seen that the light rays are distributed at a density proportional to the intensity distribution.

FIG. 19 shows that the incident light beam as shown in FIG.
FIG. 5 is a diagram showing the position of a light beam when it reaches the second optical element 104 after being deflected by the optical element 103. It can be seen that the distribution of the intensity distribution is effectively realized because the distribution is almost uniform in the area corresponding to the shape of the liquid crystal panel.

FIG. 20 shows the distribution of rays at the point where the rays emitted from the second optical element 104 propagated 20 cm. The shape is almost the same as that of FIG. 19, and it can be seen that the second optical element 104 effectively realizes the directivity of light rays.

With these effects, as is apparent from the figure, the light emitted to the outside of the panel is small, so that the power of the light source can be effectively utilized. First optical element 10
3. Even if the loss of light in the optical system using the second optical element 104 is considered to be about 15%, it is possible to realize a brightness that is about 1.2 to 1.5 times that of the case where these are not used. This value is obtained by calculating the number of rays in the simulation because the rays are distributed so that the number of rays is proportional to the energy of light. Note that this value depends on the design, the arrangement of elements, and the size.

When constructing an optical element, in the case of a pattern in which contour lines are drawn on the phase transfer function for each wavelength, the first-order diffracted light is diffracted in a desired direction. In this case, the light is deflected in a direction in which the phase shifts by one wavelength (2π radian) between the adjacent contour lines.

FIG. 21 shows how vertically incident light is deflected. As shown in FIG. 21, the deflection angle θ due to diffraction is sin θ = λ / p. Where λ is the wavelength and p is the grating pitch. In the case of this embodiment, the minimum grating pitch is about 5.7 μm. The shape of the groove forming the diffraction grating is determined under the condition that light does not leak in directions other than a desired direction. When using the first-order diffracted light, the phase delay may be linearly changed from the left end to the right end of the groove, and the optical path difference may be shifted by one wavelength in the adjacent groove. This may be formed in a sawtooth shape as shown in FIG. 21, and a groove having a height h of λ / (n−1) may be formed. Here, n is the refractive index of the optical element material. When θ is large, h = λ / (n-cos θ), as described later.

At this time, a desired deflection can be imparted to a specific wavelength, but when a wide range of wavelengths such as white light is included, there is a drawback that the deflection largely changes depending on the wavelength. In order to solve this, there is a method of using high-order diffracted light. In other words, the N-th order diffracted light is used to utilize light that is deflected in a direction in which the phase shifts by N wavelengths in adjacent grooves. At this time,
The grooves have N times both the grating pitch and the depth.

FIG. 22 shows changes in groove shape when high-order diffracted light is used. The inclination of the surface of the triangular groove is h / p = sin θ
/ (N-1). If the slope can be manufactured accurately, the pitch may have a large error, or there is virtually no restriction on the pitch. When the N-th order diffracted light is designed to be used for the light of wavelength λ0, the wavelength is λ = λ0
For the light of × N / (N + m), the (N + m) -order light is deflected in the desired direction with the maximum diffraction efficiency (m = ±).
1, ± 2, ...). Most of the power of light of other wavelengths is also deflected in the vicinity of the desired direction. The larger N is, the higher the accuracy and efficiency are, but the detailed structure of the phase transfer function cannot be reflected. Therefore, the actual number is determined in consideration of the required accuracy. In the case of this embodiment, a sufficient effect can be expected when N is in the range of about 8 to several hundreds.

The above is an example of the case where the optical element according to the present invention is configured as a transmission type diffraction grating. However, when the optical element is configured as a reflection type diffraction grating, the unevenness is reversed and the scale of the undulation changes. Similarly, an optical element can be constructed.

The optical element when N is large is shown in FIG.
Alternatively, in FIG. 7, a surface having a large thickness is sequentially shifted in the optical axis direction. That is, for a predetermined surface shape designed assuming that the optical element is configured not as a diffractive optical element but as a reflective optical element or a refractive optical element, the height from a predetermined reference plane is constant. The surface is divided by the boundary line and the parallel movement to the reference parallel side by a certain height is achieved, or a shape similar to or the same as that obtained by repeating the operation is realized. Such an optical element can be viewed as a reflective or transmissive optical element having a surface whose surface shape is continuous in a plurality of regions divided by boundaries. That is, as compared with the image viewed as a diffractive optical element with a large N, the subjective natural image changes depending on the size of N, but the image is substantially the same. By doing so, the thickness of the optical element becomes substantially constant over the entire surface of the optical element, so that the material can be reduced. Alternatively, advantages such as high resistance to changes in temperature and humidity can be obtained.

FIG. 23 shows the shape of a reflective or transmissive optical element having a surface whose surface shape is continuous in a plurality of areas divided by boundaries. FIG. 23 shows an optical element 150 having a continuous surface as a whole and a surface shape of an optical element 151 having a piecewise continuous surface that realizes the same function.

(Fourth Embodiment) FIG. 24 shows a fourth embodiment of the present invention.
It is a figure which shows the structure of the illumination optical system in the projection type liquid crystal display device which concerns on embodiment.

Light source 101 such as metal halide lamp
The light emitted from is reflected by the spheroidal reflecting mirror 102, and is further shaped by blocking the ambient light by the aperture plate 130. The light diverging in the optical path after passing through the aperture of the aperture plate 130 is the first optical element 103 and the second optical element 10.
With 4, the light beam is converted into a rectangular uniform light beam, and directivity is imparted. The subsequent configuration of the device of this embodiment is the same as the above-described device of the three-plate type or the single-plate type. In addition, FIG.
The case where the positions of the first and second optical elements 103 and 104 and the distance between them are different is shown.

According to the fourth embodiment, by setting the aperture diameter of the aperture plate 130 to be small, it is possible to obtain a light beam having better directivity. Therefore, the present embodiment has an advantageous configuration when a liquid crystal panel in a mode that requires a light beam having a good directivity is used or when it is desired to obtain high-quality display characteristics.

FIG. 25 is a view showing the arrangement of the illumination optical system when the lens 131 is inserted in front of the first optical element 103.

In this case, since the first optical element 103 does not need to have the function of focusing light, the deflection angle to be added becomes smaller than that in FIG. As a result, the influence of chromatic dispersion is reduced, and an optical system with high efficiency or accuracy can be constructed. In this way, among the functions that the first optical element 103 or the second optical element 104 takes, the functions that can be taken by a conventional general optical element are separated,
It is generally possible to use the optical elements in combination without being limited to the fourth embodiment.

In this case, the general optical element may be inserted either before or after the first optical element 103, before or after the second optical element 104, or in a plurality of places, and the place and the number of sheets are limited. There is no. At that time, the first optical element 103
The second optical element 104 and the second optical element 104 can be designed in the same manner as in the above-described embodiment by optimizing the phase transfer function on the basis of the configuration, and all the modifications are included in the present invention. It is a thing.

(Fifth Embodiment) FIG. 26 shows a fifth embodiment of the present invention.
It is a figure which shows the structure of the illumination optical system in the projection type liquid crystal display device which concerns on embodiment. In FIG. 26, light emitted from a light source 101 such as a metal halide lamp is reflected by a spheroidal reflecting mirror 102 and further shaped by being blocked by ambient light by an aperture plate 130. Aperture plate 13
The light diverging in the optical path after passing through the 0 aperture is converted into a substantially rectangular light beam by the four optical elements 143-146,
At the same time, directivity is imparted. The subsequent configuration of the device of this embodiment is the same as that of the above-described device of the three-plate type or the single-plate type.

In the case of this embodiment, the optical elements 143 to 14 are used.
The first optical element 103 in the previous embodiment is composed of three elements 5 and the optical element 146 is the second optical element in the second embodiment.
It corresponds to the optical element 104. Alternatively, from a different point of view, the first optical element 103 in the previous embodiment is configured with two optical elements 143 and 144, and the optical elements 145 and 1
It may be considered that 46 constitutes the second optical element 104 in the previous embodiment.

The optical elements 143, 14 in this embodiment
6, the phase transfer function is a function of only y, and the optical elements 144 and 145 are functions of only x. In the case of the present embodiment, since the phase transfer function has translational symmetry in one direction as described above, the grooves are parallel straight lines.
Therefore, it has a feature that the production of the optical element becomes extremely easy. Although the number of optical elements increases, the optical loss increases by that amount, but it has an advantage that an optical element can be inexpensively and rapidly developed and manufactured, and is particularly advantageous in popular products.

As a modification of this embodiment, a modification of the combination of the direction of the grating groove and the order of the optical elements can be considered. The structure may be such that it enters the optical element having the phase transfer function that is a function of only x, and the order thereafter may be arbitrary. Further, the groove direction is not limited to the vertical direction and the horizontal direction, and diagonal directions may be combined. Further, also in the case of this embodiment, the grating does not necessarily have to be independent as each optical element. For example, the optical elements 143, 144 may be realized as a single optical element having grooves formed on the front and back. When the distance between the optical elements 143 and 144 is small, the effect of substantially reducing the number of parts can be expected. Also,
Since the number of optical elements is reduced, light loss is also reduced. Not limited to the optical elements 143 and 144, it is an example of an embodiment for realizing the gist of the present invention to realize any continuous diffraction grating surface as a component in which those diffraction gratings are formed on the front and back surfaces. It is included in the present invention.

In the first to fifth embodiments described above, the optical element is designed to irradiate the rectangular liquid crystal panel with light of uniform intensity, but it is suitable for the characteristics of the projection lens where the periphery becomes dark. Then, the optical element may be designed in advance so that the peripheral portion is slightly brighter than the central portion. In this case, the uniformity of brightness on the screen is further improved. In designing, the distribution of the target reaching points may be arranged so that the density is high in the peripheral portion. Alternatively, the same effect can be obtained even if the design is performed assuming that the fall of the peripheral intensity in the distribution of the incident light is more than the actual one.

Further, in the first to fifth embodiments, the beam shape of the light beam is converted from the circular shape to the rectangular shape so that the rectangular screen has the maximum effect, but the circular area is illuminated with uniform brightness. In this case, a desired beam shape can be obtained by combining concentric grating patterns. It is also possible to transform the light beam into a triangular shape, a pentagonal shape, or any other arbitrary beam shape. In short, the sample light beam and the target reaching point may be set and designed so that the outgoing light beam has a desired beam shape.

Furthermore, in the first to fifth embodiments, both the first and second optical elements have been described as independent optical elements, but they may be combined with other elements. For example,
In a normal projection type liquid crystal display device, an unnecessary light blocking filter such as an infrared blocking filter or an ultraviolet light blocking filter is generally inserted after the light source for the purpose of blocking unnecessary light such as light other than visible light. Is. A diffraction grating may be formed or attached on the front surface or the back surface of these unnecessary light blocking filters so as to have the function of the optical element according to the present invention. Or, conversely, these unnecessary light blocking filters may be formed on the front surface and the back surface of the optical element according to the present invention. With such a configuration, it is possible to reduce light loss, such as reducing the number of component surfaces through which light rays pass and reducing unnecessary reflection of light, as compared with the case of configuring as an independent element.

(Sixth Embodiment) FIG. 27 shows a sixth embodiment of the present invention.
It is a figure which shows the structure of the optical system of the projection type liquid crystal display device which concerns on embodiment.

Light source 301 such as metal halide lamp
The light (white light) emitted by the is reflected by the spheroidal reflector 30.
The reflected light beam is reflected at 2, and in this case, the focused light beam is focused at almost one point. This light beam is guided to the optical element 303 having a function of making the intensity distribution uniform. The light beam that has passed through the optical element 303 is incident on a condenser lens 304 (a cylindrical lens in the example in the figure) 304, and becomes a parallel beam with a uniform intensity distribution.

The light beam that has passed through the condenser lens 304 is
As in the first embodiment shown in FIG. 1, a dichroic mirror 105 that transmits only light having a wavelength near red, and a dichroic mirror 106 that transmits only light having a wavelength near green and reflects light having a wavelength near blue. The liquid crystal panel 10 displays an image corresponding to each wavelength component by using the cold mirror 107 as well as being decomposed into three color components by
8 to 110, and further liquid crystal panels 108 to 1
The light modulated by 10 is transmitted to the cold mirror 111,
After being combined with the dichroic mirrors 112 and 113, they are projected onto the screen 115 by the projection lens 114, and a color image is displayed on the screen 115.

FIG. 28 (a) is a sectional view passing through the center (optical axis) of the optical element 303. This optical element 303 is
A flat transparent substrate such as a glass substrate is formed, and a groove having a constant angle θ and a constant height h is formed on one surface of the substrate in a concentric or spiral shape. . This optical element 303 has a shape similar to that of a Fresnel lens, but when viewed with respect to the cross-sectional shape when the element is cut by one plane passing through the optical axis, the angle θ of the cut groove is almost constant. It is characterized by the fact that
The light beam of the light beam incident on the optical element 303 is refracted as shown by the arrow drawn at the top of the figure.

The operation of the optical element 303 will be described with reference to FIG.

Light emitted from the light source 301 shown in FIG.
The focused light beam 401 reflected by 2 has a dark spot 402 due to the shadow of the light source 301 at the beam center. Since the optical element 303 refracts the light beam by the groove and has the same effect as that of the prism, even if the incident light beam 401 has a dark spot 402 at the center, as shown in FIG. The light beam 4
In 03, there are no dark spots and the intensity distribution is relatively uniform.

Further, the optical element 303 is arranged in the optical path of the light beam 401, in the vicinity of the focal point P of the light beam 401 and in front of the traveling direction of the light beam 401. When the optical element 303 is arranged at such a position, the light beam 403 that has passed through the optical element 303 is not dispersed and has directivity, so that the light utilization efficiency is also improved.

Of the light transmitted through the optical element 303, the light beam emitted from the upper half point 411 of the incident side light beam 402 is the light beam as shown by the point 413 of the emission side light beam 403. Most come in the lower half of 403, but some may even slightly reach the upper half of light beam 403, such as rays exiting point 412 and reaching point 414. Therefore, inside the double circle inner circle 404 representing the light beam 403 on the exit side, two kinds of light having directivity are mixed, and a bright spot appears.

In this way, the light source 301 shown in FIG.
The converging light beam 401 reflected by the reflecting mirror 302 passes through the optical element 303, and as a result, as shown in FIG. 29, the light beam 4 having an intensity distribution in which the dark spot at the center of the beam disappears.
Is converted to 03, and the uniformity of the intensity distribution is improved.

30 and 31 are diagrams showing the intensity distributions of the incident light beam 401 and the outgoing light beam 403 of the optical element 303, which are represented by marking small dots at a density proportional to the intensity. As shown in FIG.
Optical element 3 reflected by the spheroidal mirror 302 of
The intensity distribution of the incident light beam 401 on the light source 03 is gradually weakened from the center of the beam toward the outside, but a dark spot (a region without a point) due to the shadow of the light source 301 itself appears near the center. When the light beam 401 is made incident on the optical element 303 to redistribute the light intensity, the emitted light beam disappears because the peripheral light rays are gathered at the beam center as shown in FIG. , Instead, a bright spot appears.

FIG. 32 is a view obtained by cutting FIGS. 30 and 31 along one plane passing through the center of the optical axis. The horizontal axis represents the distance from the center of the optical axis, and the vertical axis represents the light intensity. In the figure, the solid line corresponds to the incident light beam to the optical element 303 (FIG. 30), and the dotted line corresponds to the outgoing light beam from the optical element 303 (FIG. 31). The broken line represents the intensity distribution of the emitted light beam when a conical prism according to the conventional technique is used instead of the optical element 303. As is clear from FIG. 32,
By using the optical element 303 according to this embodiment,
It can be seen that the light intensity distribution of the light beam can be redistributed to make the intensity distribution uniform.

Further, since the optical element 303 of the present invention has a planar shape as compared with the bulk-shaped conical lens based on the prior art, it dissipates heat well and is not easily destroyed by heat. In addition, since it is possible to easily make the optical element 303 to be large and thin, the degree of freedom in designing the device becomes very high. Therefore, (1) By designing the light power so that it is not concentrated at one point, it becomes even more resistant to thermal destruction.

(2) An optimum design can be made with an emphasis on improving directivity and illuminance.

(3) Since it becomes thin, it does not become so large even if a plurality of optical elements are used.

As described above, there are various advantages by increasing the degree of freedom in design.

Next, the structure of the optical element 303 will be described in more detail. The optical element 303 may be selected so that the groove pitch and the diffracted light are diffracted in a desired direction. That is, as shown in FIG.
In order to allow the light to be bent by an angle θo, p may be determined so that p · sin θo = λ, where λ is the wavelength of light and p is the pitch of the grooves of the optical element 303. The angle θ of the slope of the groove may be determined so that the light beam is refracted at a desired angle. Specifically, when the angle of the groove slope is θ, the groove slope height is h, and the refractive index of the constituent material (eg, glass) of the optical element 303 is n, as shown in FIG. 28, n · cos θ = Cos (θ−θo), h =
λ / (n-cos θo).

When light is diffracted by the first-order diffraction in the optical element 303, light having a specific wavelength bends to a desired angle, but light having a wavelength outside of that does not bend to a desired angle. This is inconvenient when the incident light beam to the optical element 303 includes a wide range of wavelengths such as white light. Therefore, when such a problem occurs, higher-order diffracted light may be used. This state is shown in FIG. Primary, secondary,
..., the angle θ of the slope of the groove for any of the Nth orders
Are the same.

Further, in the conventional conical prism, the optical element 303 according to the present embodiment is shown in FIG. 29, whereas the conical prism must be arranged near the focal point of the converging light beam (focal point of the light source). As shown in the figure, it was confirmed that even when the light was separated from the focal point, the performance did not substantially deteriorate in terms of redistribution of light intensity. 34-
This state is shown in FIG. These three figures show the light intensity on one plane perpendicular to the central axis of the emitted light beam using one optical element 303. The horizontal axis represents the distance from the central axis, and the vertical axis represents the light intensity.

FIG. 34 shows a case where the groove inclination angle θ shown in FIG. 28 is 50 °, FIG. 35 shows a case where θ is 55 °, and FIG.
Is 60 °, and in both cases, the optical element 303 is moved from the spheroidal reflecting mirror 302 at a position of 54.4 mm (this position is the focal position of the reflecting mirror 302) or sequentially away from the spheroidal reflecting mirror 302 (60 (-90 mm) is overlaid. It can be seen from FIGS. 34 to 36 that none of the requirements has a significant influence. Moreover, the optical element 30
3 is the focusing point of the incident beam, that is, the reflecting mirror 30 as described above.
When the light is moved away from the focal point position of 2, the optical power of the optical element 3
Since it is not concentrated on one point on 03, distortion itself due to heat is unlikely to occur, and there is an advantage that it is more resistant to thermal destruction.

In the optical element 303 of FIG. 28 (a), a groove is formed so that the slope of the one mainly used for refracting a light beam becomes thinner from the inner side to the outer side. Of the two types of surfaces that make up the groove, the slope with the angle θ that is mainly used for refracting light is referred to as “first
The surface "and the surface parallel to the central axis will be referred to as the" second surface ". In the example of the optical element 303 shown in FIG. 37, the surface having the angle θ1 with respect to the central axis is the first surface, and the surface having the angle θ2 is the “second surface”. At this time, the second surface does not necessarily have to be parallel to the central axis. Further, a reflection film may be attached to the second surface, or a treatment may be performed so as to form a diffusion surface.

FIG. 38 shows the optical element 303 of FIG. 28 (a).
FIG. 3 is a diagram illustrating in detail a situation in which the second surface is inclined in FIG.

It is assumed that the position on the left side of FIG. 38 where the light ray penetrates the element and the position on the right side of the drawing where the angle of the slope is shown are both located at the radius r from the central axis.
The rays I and O are two rays that are condensed at a certain point and then refracted in the vicinity of the second surface near the radius r. The ray I is slightly inside the second surface and the ray O is slightly Is refracted on the outside. In this situation, the ray O in the figure
In order that neither of the above and the light ray I intersect the second surface, the inclination angle θ2 of the second surface should be selected so as to satisfy θi <θ2 <θo. However, θi and θo are functions of the radius r. If this relationship is not met, the refracted ray I
Alternatively, the light ray O before being refracted is refracted or reflected by the second surface and scattered, so that the utilization efficiency of light decreases.

In the case of actual design, it is desirable to select θ2 as θ2 = (θi + θo) / 2 with a slight margin taken into consideration so as to satisfy θi <θ2 <θo. However, θi <0 near the center where the radius r is small. This may cause inconvenience when manufacturing the device, so correction is made so that 0 <θ2 <θo.

FIG. 39 shows various examples of the overall shape of the groove formed in the optical element 303.

FIG. 39A shows an example in which the groove is formed in a rectangular loop (rectangular shape) having the same center and different sizes, that is, a multiple loop shape composed of a plurality of concentric rectangular loops. In this case, an incident light beam having a dark spot at the beam center and a circular beam shape shown on the left side of FIG. 39A has no dark spot as shown on the right side of FIG. The emitted light beam having a rectangular shape is converted, and the uniformity of the intensity distribution is improved. In the example of FIG. 39 (a), the intensity distribution of the emitted light beam is made uniform, and the beam shape is rectangular, which is suitable for a liquid crystal display device using a rectangular liquid crystal panel.

39 (b) and 39 (e) show an example in which the groove is formed in a circular spiral shape. In this case, the beam shape of the emitted light beam is circular, but there is an advantage that the intensity distribution is made uniform.

FIG. 39 (c) shows an example in which the groove is formed in an elliptical spiral shape, that is, an elliptical multiple loop shape. In this case, the intensity distribution of the emitted light beam is made uniform and the beam shape is elliptical. Therefore, when it is applied to a normal liquid crystal display device using a rectangular liquid crystal panel, the light utilization efficiency is improved. 39 (a), FIG. 39 (b) or FIG.
Improved compared to (e). In particular, the ratio of the minor axis to the major axis of the ellipse is the aspect ratio of the liquid crystal panel (eg 3: 4 or 9:16).
By matching with, there is an advantage that the utilization efficiency of light is further improved.

FIG. 39 (d) shows an example in which it is formed in a rectangular multiple loop shape with rounded four corners, that is, in a rectangular multiple loop shape. In this case, the intensity distribution of the emitted light beam is made uniform and the beam shape is rectangular. Therefore, when applied to a normal liquid crystal display device, the light utilization efficiency is higher than that in the example of FIG. 39 (c). Further improve. Also in this case, as in the case of FIG. 39C, by making the aspect ratio of the rectangle match the aspect ratio of the liquid crystal panel (for example, 3: 4 or 9:16), it is possible to further improve the light use efficiency. Needless to say.

As described above, even if the angle of the inclined surface of the groove of the cross section when cut on the plane differs depending on how to select one plane passing through the optical axis, all such modifications are included in the present invention. .

Although the groove of the optical element 303 is formed on the incident surface side of the substrate in this embodiment, it may be formed on the exit surface side. Further, in FIG. 28 (a), the groove is formed so that the slope of the groove becomes thinner from the inner side to the outer side, but conversely, the groove is formed so that the thickness becomes thicker from the inner side to the outer side. Good.

Further, although the optical element 303 is constructed as a transmissive element in this embodiment, it may be constructed as a reflective element. When configured as a reflective element,
A substantially similar optical element can be constructed by inverting the irregularities and changing the scale of the undulations.

On the other hand, when a transmissive screen is used, it is incorporated in a device integrated with the projection device, but when a reflective screen is used, it may be configured as a device integrated with the projection device. A projection lens may be integrally configured as a projection device for using an independent single screen. In addition, a field lens may be inserted immediately after the liquid crystal panel in order to improve light utilization efficiency and reduce the size of the projection lens aperture.

In order to reduce the size, weight and cost of the device, a single plate type structure may be used in which a single liquid crystal panel equipped with color filters is used instead of three panels. The number of panels is not particularly limited. The single-plate configuration does not require a dichroic mirror or a cold mirror for color separation or color combination, and thus has a feature that the device can be configured with a small number of parts.

Further, although the transmissive liquid crystal panel is used as the spatial light modulator, it may be a reflective liquid crystal panel or may be an array of micromirrors instead of the liquid crystal. Not limited.

A light source 301 such as a metal halide lamp
The light (white light) emitted by the is reflected by the spheroidal reflector 30.
It becomes a converging light beam that is reflected by 2 and condensed at almost one point, but this converging light beam is obtained by a rotating parabolic reflector instead of a spheroidal reflector. It may be obtained by condensing light with a lens, and the method of converting the light from the light source into a converging light beam is not particularly limited.

In the above description, the optical element 303 shown in FIG.
As shown in FIG. 8 (a), the case where the optical element 303 is installed on the side farther from the light source with respect to the focus (in front of the focal point in the traveling direction of the light beam) has been described in detail. It is also possible to adopt a configuration in which it is installed on the side close to the light source (backward in the traveling direction of the light beam from the focusing point).

For this purpose, the optical element 303 shown in FIG. 28B is used in place of the optical element 303 shown in FIG. The optical element 303 of FIG. 28B is the same as that of FIG.
The pitch p of the groove and the angle θ of the slope of the groove are the same as those of FIG. 28A, but have the characteristics of just inside out as those of FIG. 28A. Then, the action of the optical element 303 of FIG. 28 (b) on the light beam is as shown in FIG. 29 (b), and the same effect as in the case of using the optical element 303 of FIG. 28 (a) is obtained. Further, the modified example using the optical element 303 of FIG. 28A can be applied to the optical element 303 of FIG. 28B.

(Seventh Embodiment) In the sixth embodiment, an optical element is formed by forming a groove having a constant angle on a flat substrate and having a constant height in a concentric or spiral shape. Although 303 is used, a function equivalent to this may be realized by the distribution of the phase transfer function.

The solid line in FIG. 40 is a diagram showing the characteristic of the optical element according to the present embodiment. The horizontal axis represents the distance from the center (optical axis), that is, the distance toward the outer peripheral side, and the vertical axis represents the phase transfer function. Represents As shown in FIG. 40, the optical element of the present embodiment has a characteristic that the phase transfer function gradually decreases when a half line is drawn from the center toward the outer circumference. Even when the optical element of this embodiment is used instead of the optical element 303 in FIG. 27, the rays of the incident light beam are similarly refracted.

The case where the optical element 303 is installed on the side farther from the light source with respect to the focal point (in front of the focusing point in the traveling direction of the light beam) has been described above. It is also possible to adopt a configuration in which it is installed on the side closer to the light source (behind the focusing point in the traveling direction of the light beam). For this purpose, the optical element 303 having the characteristics shown by the broken line in FIG. 40 is used. That is, the optical element 303 in this case has the characteristic that the phase transfer function increases with the distance from the center.

The rate of decrease or increase of the phase transfer function may differ depending on how to select the above half line. That is, the equiphase transfer function line may have an elliptical shape, a quadrangular shape, or another shape instead of a circular shape. In this case, the Fresnel lens is significantly different from the Fresnel lens in that it is processed so that the increasing amount of the phase change given to the light increases or decreases from the center toward the periphery by an amount proportional to the radius.

(Eighth Embodiment) FIG. 41 is a view showing the arrangement of an optical system of a projection type liquid crystal display device according to the eighth embodiment, which uses two optical elements. In the figure, the light (white light) emitted from a light source 501 such as a metal halide run is reflected by a reflecting mirror 502 having a spheroidal shape, and becomes a light beam that is condensed at almost one point. This light beam
By passing through the first optical element 503 having the same configuration as the optical element 303 described in the sixth or seventh embodiment,
The dark spot at the center disappears, resulting in a light beam with a uniform intensity distribution.

The light beam whose intensity distribution has been made uniform by the first optical element 503 further passes through the second optical element 504 for improving the directivity of the light beam, thereby performing the sixth and seventh embodiments. There is an advantage that the deterioration of the directivity due to the mixture of the light beams having two types of directivity in the form in the light beam emitted from the optical element 303 is suppressed and the bright spots are suppressed.

The light beam that has passed through the second optical element 504 is condensed by the first condenser lens 505 and is incident on the liquid crystal panel 506, and then the second condenser lens 50.
After being condensed by 7, the light passes through a diaphragm 508 and is guided to a screen (not shown) by a projection lens 509.

The operation of the first and second optical elements 503 and 504 in this embodiment will be described with reference to FIG.

As shown in FIG. 42, the light source 501 of FIG.
Focused light beam 6 emitted from the mirror and reflected by the reflecting mirror 502.
01 is a dark spot 60 due to the shadow of the light source 501 at the center of the beam.
2 As described in the sixth embodiment, the first optical element 503 refracts the light beam by the groove and has the same effect as the prism. Therefore, even if the incident light beam 601 has a dark spot 602 at the center, As shown in FIG. 42, the light rays in the peripheral portion of the beam are focused on the central portion by the first optical element 503. At this time, the innermost light ray 611 of the incident light beam 601 is secondly reflected at a point 612 reaching the center of the optical axis.
By disposing the optical element 504, it is possible to prevent the light rays on the inner peripheral portion on the emission side of the second optical element 504 from exceeding the center of the optical axis and overlapping with the light rays arriving from the outer peripheral portion.

That is, in the present embodiment, the bright spots seen in the light beam 403 emitted from the optical element 303 in the sixth embodiment as shown in FIG. .

Actually, in the configuration of this embodiment, the light intensity distribution of the light beam on a plane perpendicular to the central axis at a certain point on the exit side with respect to the incident light beam as shown in FIG. 30 was calculated. The results shown were obtained. Figure 43
The middle and horizontal axes represent the distance from the center, and the vertical axis represents the light intensity. Also, the solid line in FIG. 43 indicates the light intensity distribution of the incident light beam shown in FIG. 30, the broken line indicates the case where only the optical element 503 (the optical element 303 of the sixth embodiment) is arranged, and the dotted line indicates the case of this embodiment. The light intensity distributions when both the optical elements 503 and 504 are arranged are shown in FIG. The arrangements of the two optical systems are basically the same. As is apparent from FIG. 43, although a bright spot is formed at the center of the emitted light beam, the size of the bright spot is smaller than that in the case where only the optical element 503 (303) is provided. It can be said that the characteristics are improving.

As described above, according to the present embodiment, by adding the second optical element 504 newly, the directivity of the light beam is improved, the light utilization efficiency is improved, and
The size of the bright spots is suppressed, and the light intensity distribution can be made more uniform.

41 shows a single plate type liquid crystal display device for the sake of simplicity, it can be said that the first and second optical elements can be applied to the three plate type liquid crystal display device as in the previous embodiments. There is no end. Further, although the case where two optical elements according to the present invention are used has been described in the present embodiment, three or more optical elements may be used.

Furthermore, the present invention can be applied to various optical information processing apparatuses, in which case a spatial light modulator may be used, or a lattice mask pattern may be arranged instead of the spatial light modulator. You can also

(Ninth Embodiment) FIG. 44 is a view showing the schematic arrangement of an optical device according to the ninth embodiment. In FIG. 44, the device of the ninth embodiment includes a plurality of optical elements ((n-
1) is used to form a light beam having a desired shape having a substantially uniform intensity distribution.

In FIG. 44, the light beam generator 200
The light beam 301 emitted from the laser beam passes through the first to (n-1) th optical elements 203 to 205 and reaches the surface 210 where the desired light intensity distribution is to be obtained. Here, the optical element of the present invention has the same function as the optical element shown in FIG. 8, for example.

That is, the optical element in the ninth embodiment will be described in detail later (11th embodiment).
However, the optical element is designed so that the position of the output light on the target surface corresponding to the incident position is set and the output light reaches the set position.

Here, on the target surface, output light of a desired shape having a substantially uniform light intensity distribution can be obtained. In addition, the uniform light intensity distribution in this case means that, for example, in the target surface, considering the shape of a rectangular light, the central portion is brighter than the peripheral portion (for example, the brightness of the central portion is peripheral. About 2 to 3 times).

FIG. 45 is a diagram showing a modification of the ninth embodiment. FIG. 45 shows an example in which the number of optical elements is not one but only one. The use of multiple optical elements has the advantage that chromatic aberration can be corrected and the degree of freedom in adjusting the intensity distribution of light is increased by combining multiple optical elements. As in the example, by configuring with only one optical element, the configuration of the optical device becomes simple.

(Tenth Embodiment) FIG. 46 is a view showing the schematic arrangement of an optical device according to the tenth embodiment. Figure 46
In the optical device of FIG. 44, an optical element 206 that adds directivity (parallel, focusing, or divergence) to the incident light beam is added to the position of the target surface 210 in the optical device of FIG.

As described in the ninth embodiment, in FIG. 44, the light transmitted through the optical elements 203 to 205 has no directivity, but has a uniform light intensity distribution and a desired shape on the target surface. . However, as it is, for example,
When using a projection type optical device, it is desirable to have directivity like a parallel beam. Therefore, the optical beam having a desired directivity (for example, parallel) is obtained by arranging the optical element 206 on the target surface in order to give the light beam having a uniform intensity distribution and a desired shape a directivity. .

FIG. 47 is a diagram showing a modification of the tenth embodiment. FIG. 47 shows an example in which the number of optical elements for obtaining a light beam having a uniform desired shape is not one but a single optical element. That is, it is a diagram showing an example in which an optical element that imparts directivity is arranged on the target surface of FIG. 45. Also in this case,
As described in the ninth embodiment, the optical device can be configured with a simpler configuration than that of FIG.

When a plane for obtaining a desired light intensity distribution is set at a position farther from the light beam generator than the position of the optical element 206, if high directivity is required at that position, Since the directivity and the light intensity distribution on 206 are determined by the directivity and the light intensity distribution, it is possible to design each optical element. When high directivity is not required, the optical element for imparting directivity is not necessary, and thus the configuration similar to that of the ninth embodiment may be used.

46 and 47 show the example in which the directivity is given so that the light beams are parallel, the present invention is not limited to this, and the directivity of the light beam after passing through the optical element 206 is It is not necessary that all the rays of light that compose are parallel. As shown in FIG. 48, the directivity may be such that it spreads (diverges) around a certain point, or it may be the directivity that converges toward a certain point (focus). In such a case, the cross-sectional light intensity distribution on an arbitrary plane perpendicular to the central axis after passing through the optical element 206 has a desired distribution shape and has an expanded or reduced shape. . Further, the directivity of the light beam after passing through the optical element 206 can be intentionally disturbed.

When designing, exit from the light beam generator and set 1
Each ray before reaching the first optical element is designed under the condition that it does not intersect with any two rays except that all the rays converge at one point. For example, in FIG.
A light beam obtained by guiding a light beam emitted from a light source that can be regarded as a point light source with a reflecting mirror such as 9 satisfies this condition. Although this condition is not strictly satisfied in reality, it is effective in a system that is approximately satisfied.

(Eleventh Embodiment) In the eleventh embodiment,
A specific design method of the optical element according to the present invention will be described. FIG. 50 is a diagram showing a schematic configuration of the optical device according to the eleventh embodiment. The device of this embodiment has the same basic configuration as the device of FIG. 47, but uses a point light source as the light source.

Positioning of light rays on the entrance surface and the exit surface will be described.

It is assumed that the point light source 300 is located on the central axis of a system symmetrical about the central axis. Consider an arbitrary ray of light 301 emanating from a light source. Consider a case where this light beam enters the position of radius x2 from the center of the first optical element 203 and reaches the position of radius x3 from the center on the second optical element 206. Let Li (x2) be the actual light intensity distribution on the first optical element 203. Second optical element 206
To obtain the light intensity distribution of Lo (x3) above, x2 and x
Regarding 3

(Equation 6)

If the relationship of is established, the desired light intensity distribution can be obtained. However, x2max and x3max are x2 and x3
Is the maximum value of. Assuming that the angle between the ray from the point light source and the central axis is 1, and the luminance distribution of the light source is I (θ1),
The above formula is

(Equation 7)

It can be expressed as Lo (x ') = const,
However, when Lo (x ') = 0 (| x'|> x3max),

(Equation 8)

By solving this equation, x3 can be represented by θ1.

Next, a method of determining a ray path will be described.

In the first and second elements, the incident side surface of the light beam is not grating. A cross-sectional view of the device is shown in FIG. According to the equation shown in Fig. 52, x2 is x2 = (z2-z1-d2) tan θ1 + d2 · tan (sin ^-1 (sin θ1 / n
)) And θ1. Also, θ2 is (z3-z2-d3) tan θ2 = x3-x2-d3 ・ tan (sin ^-1 (sin θ2 / n
)) Is solved by θ2. Since x2 can be represented by 1, θ2 is also determined by θ1. When the element thickness, that is, d2 and d3, is sufficiently small, this formula becomes θ2 = tan ^-1 {(x3-x2) / (z3-z2)}. Furthermore, θ3 = 0.

As described above, x2, θ2, x3 and θ3 with respect to θ1 are determined.

The groove slope angle of the optical element is determined. A concentric groove is formed on the light emitting side of each of the first and second optical elements, and the inclination angle of this groove at radii x2 and x3 is
Θ2 is the angle that the normal vector of the groove makes outside the center axis.
(X2) and Θ3 (x3). When a ray incident on the first element at the incident angle θ1 exits at the outgoing angle θ2, Θ2
Is

[Equation 9]

It is determined that Also, Θ3 is

[Equation 10]

It is determined that

The optical element according to the present invention is designed as described above.

Actual design examples are shown in FIGS. 53 is a diagram showing a design example of the emission angle from the point light source and the arrival position when two optical elements are used, and FIGS. 54 and 55 are the first optical element in FIG. 53, respectively. It is a figure which shows the example of a design of the 2nd optical element.

(Twelfth Embodiment) FIG. 56 is a diagram showing the structure of an optical system of a liquid crystal projection display device when two optical elements of the present invention are used.

In FIG. 56, the light (white light) emitted from the light source 201 such as a metal halide lamp is reflected by the spheroidal reflecting mirror 202, and becomes a light beam condensed at approximately one point 300. This light beam is converted into a light beam having a uniform cross-sectional shape of light intensity distribution in which the dark spot in the center part disappears by passing through the optical element 203 for converting the intensity distribution. After that, the light beam whose intensity distribution shape is shaped passes through the optical element 206 that improves the directivity of the light beam, thereby improving the directivity so as to become parallel rays. This light beam is condensed by the condenser lens 213 and enters the liquid crystal panel 215. After that, the light is condensed again by the second condenser lens 216, passes through the diaphragm 218, and is guided to the screen by the projection lens 219.

As described above, by using two optical elements according to the present invention, it is possible mainly to make the intensity distribution of light transmitted through the optical elements uniform and improve the directivity. Also, these optical elements can be designed as described in the eleventh embodiment above.

FIG. 57 is a diagram showing the light intensity distribution of the light beam emitted from the light source on the first optical element by the density of points, and FIG. 58 is the light intensity of the cross section of the parallel rays obtained by this optical device. It is the figure which represented distribution by the density of the point.

As described above, the light beam emitted from the point light source can be converted into uniform circular parallel rays.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the configuration of this embodiment. For example, the shape of this light intensity distribution can be converted into any shape symmetrical about the central axis.

Further, the light beam having the directivity is not a parallel beam but can be converted into a light beam having the directivity that spreads from one point. Further, the directivity can be such that the light is condensed at one point. In addition, the directivity of light rays can be intentionally deteriorated.

In FIG. 56, a single plate type liquid crystal projection device has been described for the sake of simplicity, but of course a three plate type may be used.

Further, although the case where two optical elements according to the present invention are used has been described in the present embodiment, it is also possible to use three or more optical elements, in which case the effect is further enhanced.

The present invention is not limited to the above-described embodiments of the invention, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0220]

According to the present invention, the following effects can be obtained.

As described in detail above, according to the optical element of the present invention, it is possible to obtain a predetermined (arbitrary) shape and a predetermined (arbitrary) intensity distribution with a simple structure (that is, one optical element). The incident light can be converted into a desired shape (for example, a rectangle, an ellipse, etc.) having a predetermined intensity distribution (which will be expressed as “uniform” in the following because it basically has a uniform intensity distribution).

In the first optical device of the present invention, the incident light beam is passed through the first optical element to shape the beam into a rectangular shape or an elliptical shape, and the directivity is disturbed as the beam shape is shaped. Directivity is given to the light beam by the second optical element. Normally, the light beam from a light source with a circular beam shape and uneven light intensity distribution is
By passing through the second optical element, a light beam whose beam shape is close to that of the spatial modulation element and whose intensity distribution is uniform with respect to the spatial modulation element such as a generally rectangular liquid crystal panel is obtained. It is possible to irradiate, and it is possible to improve the utilization efficiency of light using the same light source as in the past, and it is possible to illuminate the spatial modulation element with uniform brightness. In addition, the brightness and the uniformity of brightness comparable to the conventional one can be achieved under the power consumption lower than the conventional one. Therefore, if the first optical device is applied to the projection type liquid crystal display device, it is possible to improve performance and reduce power consumption.

In the second optical device, the intensity of the incident light beam is adjusted by the first optical element, which is formed by forming concentric or spiral spiral grooves having a constant angle on the transparent substrate. The distribution is made uniform, and the light beam that has passed through the first optical element is incident on the spatial light modulator with directivity. That is, since the first optical element produces the effect of a prism that refracts light rays by the groove formed on the surface of the substrate, even if the light beam from the light source system that is the incident light beam has a dark spot near the center, By moving the light of the part to the center, the dark spot will disappear in the emitted light beam,
The light intensity distribution can be made uniform. Further, unlike the bulky prism that refracts light due to its three-dimensional shape, the first optical element is made of a translucent substrate having grooves formed on its surface, and can be made very thin. The radiation is very good. Therefore, a powerful cooling device is not required and cooling is easy. Further, even if the first optical element is provided at the focal point of the reflecting mirror existing in the light source system, that is, near the focusing position of the incident light beam, there is no risk of destruction due to heat, so that it is compared with the case where a bulk prism is used. Then, the light utilization efficiency is improved. In the two-lens system (a light beam having a desired shape having a uniform intensity distribution on the first sheet and a directivity on the second sheet), the optical element can be arranged away from the vicinity of the focal position. There is no danger of thermal destruction. Furthermore, since the thickness of the first optical element may be the same even if the diameter of the first optical element is increased, a large diameter and compact size can be manufactured, which contributes to downsizing of the optical device.

Further, in the second optical device, the light beam passing through the first optical element is passed through the second optical element to give directivity, whereby the light utilization efficiency is further improved.

In the third optical device, the phase transfer function linearly decreases or increases as the incident light beam goes outward on the plane perpendicular to the optical axis.
The intensity distribution of the light beam is made uniform by the optical element, and the light beam that has passed through the first optical element is incident on the spatial light modulation element with directivity. That is, since the first optical element has the effect of a prism due to the change of the phase transfer function, even if the incident light beam has a dark spot near the center, it does not affect the peripheral area as in the first optical element in the second optical device. By moving the light in the center to the center, the dark spots disappear in the emitted light beam, and the effect of making the light intensity distribution uniform is obtained, and it is made extremely thin by the translucent substrate with a changed phase transfer function. Because it is possible, the heat dissipation is very good.

Therefore, according to the third optical device,
Even if an optical element is provided in the focal point of a reflecting mirror existing in the light source system, that is, near the focus position of the incident light beam, there is no risk of damage due to heat, so use of light is greater than when a bulk prism is used. Efficiency is improved. Furthermore, since the thickness of the first optical element may be the same even if the diameter of the first optical element is increased, a large diameter and compact size can be manufactured, which contributes to downsizing of the optical device. Further, like the second optical device, in the case of the two-lens system, the optical element can be arranged at a position deviated from the focus position, so that there is no risk of thermal destruction of the optical element.

Further, also in the third optical device, the light beam passing through the first optical element is passed through the second optical element to give directivity, whereby the light utilization efficiency is further improved.

In the fourth optical device, by disposing an optical element similar to the first optical element in the second optical device near the focusing point of the converging light beam and in front of the focusing point in the traveling direction of the light beam, Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

Also in the fifth optical device, by disposing an optical element similar to the first optical element in the third optical device near the focusing point of the converging light beam and in front of the focusing point in the traveling direction of the light beam, Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

Also in the sixth optical device, by disposing an optical element similar to the first optical element in the third optical device near the focusing point of the converging light beam and behind the focusing point in the traveling direction of the light beam, Since the directivity can be improved and the light can be incident on the spatial light modulator without using the second optical element, it is possible to make the intensity distribution uniform and improve the light utilization efficiency.

As described above, according to the optical element or the optical device of the present invention, the power of the light beam emitted from the light source is effectively used, the directivity is secured, the efficiency is high, the desired shape and the desired intensity are obtained. It is possible to realize shaping into a light beam having a distribution. This makes it possible to illuminate the liquid crystal panel with a rectangular or circular uniform light beam, which makes it possible to realize a display device with higher image utilization efficiency and better brightness than the conventional one, and with good image quality. In other words, it is possible to solve the disadvantage that the periphery of the screen is dark in the conventional device, and further realize a liquid crystal projection display device having a brighter screen than the conventional one with the same power consumption as the conventional one. Alternatively, a screen having the same brightness as that of the related art can be realized by a device having lower power consumption than that of the related art.

The present invention is effective not only for white light but also for laser light, and provides a means for converting a circular light beam into a uniform rectangular beam. Therefore, the present invention can be applied not only to the display device but also to a wide field that is required to efficiently illuminate a rectangular area. For example, the present invention can be applied to a calculation using light, an information processing device, an image processing device, and the like. Even in this case, similarly to the display device, reduction in power consumption or improvement in performance brought about by improvement in irradiation intensity can be obtained as an effect.

Furthermore, according to the present invention, it is possible to eliminate dark spots from a light beam having a dark spot at the center in the light intensity distribution of the beam cross section by using an optical element, and improve the uniformity of the light beam. can do. Moreover, the optical element of the present invention is less likely to be damaged by heat than a bulk-shaped conical lens, and has a large degree of freedom in design, such as being able to make a large and thin lens. It is possible to realize an optical device.

Since the optical element according to the present invention has fine grooves formed on the surface thereof, light rays are refracted by the grooves, and a prism effect is produced. Thereby, even if the light coming from the light source has a dark spot near the center, the light in the peripheral portion can be moved to the central portion to eliminate the dark spot. In addition, the optical element according to the present invention does not need to have a three-dimensional shape and is made extremely thin, as compared with a bulk prism that refracts by a three-dimensional shape, because the optical element according to the present invention refracts by processing applied to the surface. It is possible to dissipate heat very well. Further, even if the diameter is increased, the thickness may be the same, so that a large-diameter and compact one can be manufactured.

Since the inclination angle of the inclined surface of the groove is set for each radius with the optical axis as the center, the light intensity distribution in the radial direction of the optical element can be freely controlled. With this, the central bright spot can be erased. Further, since the groove slope angle of the second optical element which is incident after the desired light intensity distribution is obtained is set for each radius, the directivity of the light beam in the radial direction can be freely controlled.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical system of a projection type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a first example of converting an intensity distribution in the same embodiment.
The figure which shows the example of various arrangement | positioning of the 2nd optical element which gives an optical element and directivity.

FIG. 3 is a first example for converting an intensity distribution in the same embodiment.
The figure which shows the other various example of arrangement | positioning of the 2nd optical element which gives an optical element and directivity.

FIG. 4 is a first example for converting an intensity distribution in the same embodiment.
The figure which shows another various arrangement example of the 2nd optical element which gives an optical element and directivity.

FIG. 5 is a diagram showing a relationship between an optical element for converting an intensity distribution and a liquid crystal panel in a projection type liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a diagram schematically showing the principle of the case where an optical element according to a third embodiment of the present invention is composed of a transmissive optical element.

FIG. 7 is a diagram schematically showing the principle of the case where the optical element according to the same embodiment is composed of a reflective optical element.

FIG. 8 is a diagram schematically showing the principle of the case where the optical element according to the same embodiment is formed of a transmissive diffractive optical element.

FIG. 9 is a diagram schematically showing the principle of the case where the optical element according to the same embodiment is configured by a reflective transmissive diffraction optical element.

FIG. 10 is a diagram showing an example of a specific arrangement of optical elements in the same embodiment.

FIG. 11 is a diagram showing the positions of sample rays on the surface of the first optical element.

FIG. 12 is a diagram showing target reaching points of sample rays on the surface of the second optical element.

FIG. 13 is a diagram showing parameter values obtained as a result of optimization for each optical element.

FIG. 14 is a diagram showing a profile of a phase transfer function obtained for the first optical element.

FIG. 15 is a diagram showing a profile of a phase transfer function obtained for a second optical element.

FIG. 16 is a diagram showing contour lines of a phase transfer function obtained for the first optical element.

FIG. 17 is a diagram showing contour lines of the phase transfer function obtained for the second optical element.

FIG. 18 is a diagram showing positions of light rays incident on the first optical element in the simulation.

FIG. 19 is a diagram showing a position of a light beam when it is deflected by the first optical element and reaches the second optical element.

FIG. 20 is a diagram showing a distribution of light rays at a point where the light rays emitted from the second optical element propagated by 20 cm.

FIG. 21 is a diagram showing how light incident vertically on an optical element is deflected.

FIG. 22 is a diagram showing a change in groove shape on an optical element using high-order diffracted light.

FIG. 23 is a diagram showing a shape of a reflective or transmissive optical element having a surface whose surface shape is continuous in a plurality of regions divided by boundary lines.

FIG. 24 is a view showing the arrangement of an illumination optical system in a projection type liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 25 is a diagram showing a configuration of an illumination optical system in which a lens is inserted before the first optical element.

FIG. 26 is a diagram showing a configuration of an illumination optical system in a projection type liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 27 is a diagram showing a configuration of an optical system of a projection type liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 28 is a diagram showing a detailed configuration of the optical element in the same embodiment.

FIG. 29 is a view showing a main part of an optical system for explaining the operation of the same embodiment.

FIG. 30 is a diagram showing the intensity distribution of an incident light beam of an optical element for explaining the operation of the same embodiment.

FIG. 31 is a diagram showing the intensity distribution of the outgoing light beam of the optical element for explaining the operation of the embodiment.

FIG. 32 is a diagram showing the light intensity with respect to the distance from the optical axis center of the incident light beam and the outgoing light beam of the optical element and the outgoing light beam of the conventional conical prism in the same embodiment.

FIG. 33 is a diagram showing a groove shape when high-order diffracted light is used in the optical element of the same embodiment.

FIG. 34 is a view showing a light intensity distribution of an outgoing light beam when the inclination angle of the groove of the optical element in the same embodiment is θ = 50 °, using the element position as a parameter.

FIG. 35 is a diagram showing a light intensity distribution of an outgoing light beam when the inclination angle of the groove of the optical element in the same embodiment is θ = 55 °, using the element position as a parameter.

FIG. 36 is a diagram showing the light intensity distribution of an outgoing light beam when the inclination angle of the groove of the optical element in the same embodiment is θ = 60 °, using the element position as a parameter.

FIG. 37 is a view showing another example of the optical element according to the same embodiment.

FIG. 38 is a view showing still another example of the optical element according to the same embodiment.

FIG. 39 is a view showing various groove shapes of the optical element according to the same embodiment.

FIG. 40 is a diagram showing a phase transfer function distribution of an optical element according to a seventh embodiment of the present invention.

FIG. 41 is a diagram showing a configuration of an optical system of a projection type liquid crystal display device according to an eighth embodiment of the present invention.

FIG. 42 is a view for explaining the action of the first and second optical elements in the same embodiment.

FIG. 43 is a diagram showing the light intensity with respect to the distance from the optical axis center of the incident light beam of the first optical element and the output light beam of the second optical element in the same embodiment.

FIG. 44 is a diagram showing a schematic configuration of an optical device according to a ninth embodiment.

FIG. 45 is a view showing a modified example of the ninth embodiment.

FIG. 46 is a diagram showing a schematic configuration of an optical device according to a tenth embodiment.

FIG. 47 is a view showing a modified example of the tenth embodiment.

FIG. 48 is a diagram showing another modification of the tenth embodiment.

FIG. 49 is a view showing still another modified example of the tenth embodiment.

FIG. 50 is a diagram showing a schematic configuration of an optical device according to an eleventh embodiment.

FIG. 51 is a sectional view of an optical element.

FIG. 52: Uniform intensity distribution on the first sheet. The figure which shows the design example of the optical element in the case of improving directivity with the 2nd sheet.

FIG. 53 is a diagram showing a design example of an emission angle from a point light source and an arrival position in the case of two optical elements.

FIG. 54 is a diagram showing a design example of the first optical element.

FIG. 55 is a diagram showing a design example of a second optical element.

FIG. 56 is a diagram showing a case where the optical element of the invention is applied to a liquid crystal projector.

FIG. 57 is a diagram showing a dot diagram of light rays on the optical element closest to the light source.

FIG. 58 is a diagram showing a dot diagram of light rays on a surface for obtaining a desired light intensity distribution.

FIG. 59 is a diagram showing a schematic configuration of an optical system of a conventional transmissive liquid crystal display device.

FIG. 60 is a view showing a schematic configuration of an optical system of another conventional transmissive liquid crystal display device.

[Explanation of symbols]

 101 ... Light source 102 ... Reflecting mirror 103 ... First optical element 104 ... Second optical element 108-110 ... Liquid crystal panel 301 ... Light source 302 ... Reflecting mirror 303 ... Optical element 501 ... Light source 502 ... Reflecting mirror 503 ... First Optical element 504 ... Second optical element

Claims (20)

[Claims] 1. An optical element for converting incident light having a predetermined shape and a predetermined intensity distribution into output light having a desired shape having a predetermined intensity distribution. 2. The optical element according to claim 1, wherein the output light has a shape of a square, a circle, or an ellipse. 3. At least one of a phase transfer function representing the advance or lag of a phase to be given to a typical wavefront of incident light or a shape of an optical element surface is set based on optimization calculation. The optical element according to claim 1, wherein: 4. The optical element according to claim 1, wherein the output light has a central portion brighter than a peripheral portion. 5. A groove having either a concentric circle shape or a spiral shape, wherein the groove has a light intensity distribution Li (ri) on an incident surface of the optical element, the light being incident on the optical element on a desired surface. Let L o (ro) be the light intensity distribution of L, and if r i> r imax, L
When i (ri) = 0 and ro> romax, Lo (ro) =
If 0, then The optical element according to claim 1, wherein the inclination angle of the slope is set so that 6. A light source that emits a light beam having a predetermined beam shape and intensity distribution, and the beam shape of the incident light beam is either square, circular or elliptical having a uniform intensity distribution. An optical device comprising: a first optical element that is shaped into a shape; and a second optical element that imparts directivity to the shaped light beam that is incident. 7. At least one of the first optical element and the second optical element uses second-order or higher-order diffracted light of the incident light beam, and concentrates the intensity of the diffracted light in the used diffraction direction. The optical device according to claim 6, wherein: 8. The first optical element is arranged in the optical path of the incident light beam substantially perpendicularly to the optical axis of the light beam, and a groove formed of a plurality of curved groups is formed on the surface thereof. The optical device according to claim 6, further comprising a transparent substrate. 9. A first optical element, which is arranged in the optical path of a light beam having a predetermined intensity distribution, and which has a groove on the surface of which a concentric or spirally formed inclined surface with a constant angle is provided. An optical device comprising: an element; and a second optical element that is disposed in the optical path of the light beam that has passed through the first optical element and that imparts directivity to the incident light beam. 10. A phase transfer function linearly decreases or increases from the optical axis on the plane perpendicular to the optical axis of the light beam, the phase transfer function being arranged in the optical path of the light beam having a predetermined intensity distribution. A first optical element having characteristics, and a second optical element that is disposed in the optical path of the light beam that has passed through the first optical element and that imparts directivity to the incident light beam. Optical device. 11. The spatial light modulating element for displaying a desired image upon incidence of a light beam to which directivity has been imparted by the second optical element, further comprising: The optical device according to claim 10. 12. An optical system having a translucent substrate which is arranged in the vicinity of a focusing point in the optical path of a converging light beam having a predetermined intensity distribution and in which concentric circular or spiral grooves having inclined surfaces with a constant angle are formed. An optical device comprising an element. 13. A light source having a predetermined intensity distribution, disposed in the optical path of a converging light beam, in the vicinity of the converging point and in front of the converging point in the traveling direction of the light beam, and on a plane perpendicular to the optical axis of the light beam. An optical device comprising an optical element having a characteristic that a phase transfer function linearly decreases from the optical axis toward the outside. 14. A surface which is arranged in the optical path of a converging light beam having a predetermined intensity distribution in the vicinity of the converging point and behind the converging point in the traveling direction of the light beam, and on a plane perpendicular to the optical axis of the light beam. An optical device comprising an optical element having a characteristic that a phase transfer function linearly increases from the optical axis toward the outside. 15. The method according to claim 12, further comprising a spatial light modulator arranged in the optical path of the light beam that has passed through the optical element and displaying a desired image. The optical device described. 16. An optical device comprising at least one first optical element for converting incident light having a predetermined shape and a predetermined intensity distribution into output light having a desired shape having a uniform intensity distribution. apparatus. 17. The optical device according to claim 16, wherein the output light has a central portion brighter than a peripheral portion. 18. The first optical element has a groove having either a concentric circle shape or a spiral shape, and the groove has a light intensity distribution L of light incident on the optical element on an incident surface of the optical element.
i (ri) and the light intensity distribution on the desired surface are Lo (ro), and when Ri> rimax, Li (ri) = 0, ro> r
When Lo (ro) = 0 at omax, the following equation is obtained. The optical device according to claim 16, wherein the inclination angle of the slope is set so that Here, ri: position from the optical axis of the incident light beam, rimax: position farthest from the optical axis of the incident surface of the optical element, ro: on the desired surface of the output light beam corresponding to the incident light beam Position from optical axis, romax: The position farthest from the optical axis on the desired surface where the output light beam can reach. 19. A concentric or spiral shape having a slope having an angle that changes in accordance with the distance from the central axis so as to impart a predetermined directivity to light of a desired shape having the uniform intensity distribution. 17. Further comprising at least one second optical element having any of the grooves of claim 16.
The optical device described. 20. A light source for emitting a light beam having a predetermined beam shape and intensity distribution, and at least one first shape shaping the beam shape of the incident light beam into a desired shape having a uniform intensity distribution. 1
An optical element, a second optical element that imparts directivity to the shaped light beam that is incident, and an optical beam that is imparted with the directivity is incident, and light is emitted to a predetermined portion in order to display a desired image. A liquid crystal projection display device, comprising: a liquid crystal panel that allows light to pass therethrough; and a screen that displays light that has passed through the liquid crystal panel as an image.