JP2003131165A - Lighting device and image display device provided with laser light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the intensity distribution in a lighting device in which a parallelized light source is used. SOLUTION: A collimate lens 2 is arranged for the parallelized light source 1, light beams collimated with the lens are composited with a first lens L1. Further, the light beams are spatially divided by arranging a group of lens arrays ML1 and ML2, superimposed by using a second lens group L2, and projected on a face to be illuminated via a third lens (or lens group), thus a uniformized light intensity distribution is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for realizing a uniform intensity distribution in an illuminating device using parallel laser light sources.

[0002]

2. Description of the Related Art In an image display device called a projection display, a liquid crystal panel or a D is used as a spatial modulator.
MD (Digital Micromirror Device) and the like have been used, but recently, a display using an active drive type grating (diffraction grating) by a micromachine technology has been developed and attracted attention. The diffraction grating type element used is "Grating Light valve (Grating Light valve
Valve) ”(hereinafter abbreviated as“ GLV ”), which is capable of displaying a seamless (clear), clear and bright image, and uses micromachine technology, as compared with the case of using a conventional spatial modulator. It has attracted attention because it has the features of being able to be produced at a low cost and at high speeds.

To form an image using this GLV,
Of the diffracted light, Schlieren filtering that blocks the 0th order light and transmits only the ± 1st order light is necessary.

FIG. 23 shows a Schlieren filter optical system a.
It shows the main part of. Light from a light source (not shown) is condensed by the cylindrical lens L0 and G
The LV is irradiated, and the diffracted light is transmitted through the lens L1, the schlieren filter F, and the lens L2 in this order and emitted.

The rays "lt (+1), lt shown in FIG.
“(0), lt (−1)” represents the diffracted light by GLV, “lt (+1)” is the + 1st-order diffracted light, and “lt
“(0)” indicates the 0th order (diffracted) light and lt (−1) indicates the −1st order diffracted light, and only the 0th order light is blocked by the Schlieren filtering.

A reflection type element is used as the GLV, and has a structure in which a large number of minute ribbons called membranes are arranged in parallel on a substrate with an air gap. Then, of the GLV states, in the first state (when the pixels are turned off), the phases of all ribbons are aligned,
± 1st order diffracted light is not generated (only reflected light), but in the second state (when the pixel is lit), every other ribbon is attracted to the substrate side by the electrostatic force to form a reflection type diffraction grating. ± 1st order diffracted light is generated. And this ±
In order to select only the first-order diffracted light, it is necessary to perform spatial filtering (Schlieren filtering) in the Fourier plane of GLV.

Here, in order to increase the filtering contrast, it is necessary to sufficiently narrow the angular range of the incident light in the diffraction direction. This is because if the incident light beam has a spread, the light beam incident value on the filtering surface can be spread, so that leakage light occurs at the time of extinction.

As a light source used for such an optical system,
A semiconductor laser may be used. 2. Description of the Related Art In recent years, semiconductor lasers have been shortened in wavelength and have been increased in output, and therefore, their availability as a light source for an illumination optical system in a laser display, a laser printer or the like is increasing.

For example, an optical system using a semiconductor laser array bar has been proposed for GLV illumination, and its structural example is shown in FIG.

The configuration of the illumination optical system b in the first plane including the optical axis (this is referred to as "x plane") and the optical axis are included,
In addition, the configuration of the illumination optical system b in the second plane orthogonal to the x plane (this is referred to as the "y plane") is shown.

The semiconductor laser array bar c is configured as a parallel light source in which a plurality of emitters (emission sources or radiation sources) (not shown) are arranged in parallel, and the light emitted from these emitters collimate lenses d and e. Through the lenses f to i, the condensing cylindrical lens j, and the GLV through the cover glass k.
Is irradiated.

The collimator lens e is a microphone lens array in which a large number of lens elements are arranged. In addition, the emitting end face of the semiconductor laser array bar c and the lens f
The image-side focal plane and the GLV irradiation surface (to the linear region) are optically conjugate.

[0013]

By the way, what is required of an illuminating device using a laser as a light source is that the uniformity of illumination is high, parallel light can be obtained, and there is no speckle noise (or it is inconspicuous). However, in the case of conventional lighting devices, among these items,
In particular, there is a problem in that a sufficiently satisfactory characteristic with respect to uniformity cannot be obtained, or the burden of labor required for obtaining a desired characteristic is large.

For example, the intensity distribution of each emitter constituting the semiconductor laser array bar is non-uniform and the light utilization efficiency is low.

If the uniformity is poor, it leads to a decrease in efficiency.
This may cause problems such as high brightness, and may bring about an adverse effect such that the display device or the like cannot have a sufficient dynamic range.

Therefore, an object of the present invention is to realize a uniform intensity distribution in an illuminating device using a parallelized laser light source.

[0017]

In order to solve the above-mentioned problems, the present invention provides a first lens array or a lens array group for performing collimation with respect to a parallelized light source, and the first lens array or the lens array group is collimated thereby. The rays are combined by the first lens or lens group, and the second lens array or lens array group is further arranged to spatially divide the ray, and then the second lens or lens group is used. By superimposing them and projecting them onto the illumination surface through the third lens or lens group, a uniform light intensity distribution can be obtained.

Therefore, according to the present invention, the laser light from the parallelized light source is collimated by the first lens array (or lens array group), and the combined image is obtained by the second lens array (or lens array group). After spatially dividing with), it is possible to obtain illumination light having a uniform intensity distribution by overlapping again.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses laser light from a parallel light source (semiconductor laser array etc.),
The present invention relates to an optical configuration for obtaining illumination light having a uniform light intensity distribution. For example, in application to image display devices, front projection (front projection)
Type, rear projection (rear projection) type laser display, and the like, but can be widely used in other image devices including printing and recording, such as a laser printer or a recording device for recording digital image data on motion picture film. Of course, the application of the illumination device according to the present invention to laser fusion, and the application of the present invention when uniform illumination light is required for applications such as laser processing or measurement contributes to improvement in accuracy and the like. It is possible to

Before explaining the specific structure of the lighting apparatus according to the present invention, the principle of the present invention will be described.

First, the present invention is premised on using a laser beam from a parallel light source. Each light beam may be a different laser beam or a light beam having a different polarization state. Hereinafter, for convenience of explanation, it is assumed that a semiconductor laser array is used as a parallelized light source having a configuration in which a plurality of light sources are arranged in parallel.

A first lens array (or lens array group) is arranged for collimating the parallelized light sources. For the lens array, for example, one in which a plurality of lens elements are integrally formed is used, and the lens array functions as a collimating lens for each light beam from the parallelized light source.

The light rays collimated by the first lens array (or lens array group) are combined by the first lens (or lens group).

Then, by arranging a second lens array (or lens array group), the light beam is spatially divided. As the second lens array, there are a form in which a single one in which a plurality of lens elements are integrally formed is used and a form in which a plurality of lens arrays are combined to form a lens array group. Further, as the lens array, a spherical lens array, a cylindrical lens array, a gradient index lens array, or a diffractive optical element having an optical action equivalent to or equivalent to these is used. The same applies to the above-mentioned first lens array).

Then, the second lens (or lens group)
The light is superposed by the third lens (or lens group)
By projecting onto the illumination surface via, the illumination light having a uniform intensity distribution is obtained. Such illumination light is, for example, GL
Although uniform illumination can be performed by irradiating a linear region such as V, the present invention is not limited to one-dimensional illumination (linear illumination) and can be applied to two-dimensional uniform illumination.

First, a homogenizing method by superimposing beams will be described with reference to FIGS.

FIG. 1 conceptually shows the homogenization of the intensity distribution by division and multiplexing for a Gaussian beam (the intensity distribution has a Gaussian distribution). That is, as shown in the center figure, the Gaussian beam distribution curve G shown on the left side is divided into three parts (the central part G1 of the beam and the two hem parts G2 and G3) by a broken vertical line. . Then, as shown by the arrows, by moving the skirt portions G2 and G3 to the central portion G1 of the beam and overlapping them, a substantially uniform intensity distribution can be obtained.

This depends on the condition of superposition,
The present invention can be applied not only to Gaussian beams but also to laser light having a general intensity distribution.
As shown in, by dividing a beam having a slightly nonuniform intensity distribution g into a plurality of portions g1, g2, g3 along the horizontal axis direction, and by superimposing them on the central portion g1 of the beam. (Ignore the peripheral portion of the figure.) It is possible to make the intensity distribution uniform.

As described above, even with a Gaussian distribution or an irregular intensity distribution, it can be seen that the intensity distribution is averaged and the uniformity is enhanced by dividing and superimposing the distribution. For that purpose, a lens array (microlens array) may be used.

FIG. 3 shows N when the lens array c is used.
The image formation relationship of (= 3): 1 is shown. For the sake of convenience, the number of lens elements e constituting the lens array c is three, and the light emitted from the three upward arrows arranged on the object side passes through the respective elements e and then forms an image for composition. An image is formed by passing through a lens d (a single lens is shown in the figure as a representative, but the case of a lens group is also included) (the inverted image is indicated by a slightly long downward arrow).

Light rays emitted from the same object height with respect to the central axis of each lens element e are all superposed on the image side focal plane of the lens d. Therefore, the incident side focal plane of the lens array can be divided and overlapped with the focal plane of the lens.

FIG. 4 is a principle explanatory view of a light source-conjugated optical system (splitting / combining optical system).
The configuration in the x-plane including the optical axis is shown, and the configuration in the y-plane including the optical axis and orthogonal to the x-plane is shown on the lower side.

A semiconductor laser array is assumed as the parallel light source 1 to be used, and the light rays from the respective emitters are collimated lenses 2 (2f, 2s) using microlenses.
Collimate (“2s” corresponds to the first lens array described above). That is, GL
In order to separate the diffracted light of V with a high contrast by the Schlieren filter, it must be collimated parallel light in the y-plane. Here, as an example,
A lens unit manufactured by LIMO of Germany is used. In addition, this lens unit is a semiconductor laser "Fast Axis",
It has a configuration in which a cylindrical lens that collimates the divergence in each axial direction of the "Slow Axis" is combined, while the "Fast Axis Collimator" (FAC) is an aspherical cylindrical lens (see "2f" in the figure), while the other `` Slow Ax
is Collimator "(SAC) is an LD (laser diode)
It is a spherical cylindrical lens array that matches the array pitch and divergence angle of the emitters of the array bar (see "2 in the figure").
s "). For the emitter of the LD array bar, a broad area with a light emitting region width of several tens to several hundreds of μm is used in order to increase the output.

In the plane perpendicular to the active layer (in the y plane) where the divergence angle of the LD array bar is large, the rays from all the emitters are collimated by 2f which is an aspherical cylindrical lens. Since the thickness of the active layer of the LD is usually about 1 μm, it can be regarded as a point light source. Therefore, collimation makes it possible to obtain almost perfect parallel light in the y plane.

On the other hand, in the plane parallel to the active layer (in the x-plane), since the light emitting region of the emitter has a spread, the light is not perfectly parallel and has a spread with respect to the divergence angle of the emitted light. become.

Since the LD array bar has a large number of emitters arranged in parallel in the x-plane, it is necessary to associate one microlens with each emitter and perform collimation for each. In the above 2s, a plurality of cylindrical lens arrays are arranged in the x-plane, and the optimal collimation is performed in the plane for each emitter.

Normally, with respect to the divergence angle of the LD, the divergence angle in the y plane is much larger than that in the x plane.
Since the lens unit manufactured by the company uses separate cylindrical lenses for the x-plane and the y-plane, the emitted beam diameters can be independently controlled to obtain desired beam diameters. Even when a spherical lens array or the like having a normal rotational symmetry is used instead of the cylindrical lens, the conjugate relationship in the optical system including the optical elements arranged after that with respect to the emission end face of the LD. However, if the focal lengths of the collimation in the x plane and the y plane can be set independently, the degree of freedom with respect to the size of the final illumination area can be increased. Design becomes easy. Further, as the light emitting area of the LD becomes larger, the astigmatism of the light source becomes larger. Therefore, in order to correct this as well, the collimating module constituted by the cylindrical lens is optimal.

Explaining the optical action in the x plane of FIG. 4, the emitter image of the LD can be formed on the focal plane on the exit side of the first stage lens L1 (corresponding to the first lens) (arrow in the figure). (See A). Since this image is obtained by superimposing the images of all the emitters at the same place, even if one emitter is deteriorated, a part of the illumination light is not lost. In addition, due to the superposition, variations among the emitters are also averaged.

A first microlens array ML1 (having a focal length of "f") is arranged with respect to the image plane of this emitter, and it is located behind (outgoing side) by a distance f. A second microlens array ML2 (having a focal length “f”) is arranged. The microlens array ML1 is a field lens,
The light incident on a certain lens element that constitutes the ML1 is guided to the corresponding lens element at the ML2. Incidentally, these ML1 and ML2 correspond to the above-mentioned second lens array group.

When an image forming lens L2 (a lens group, which corresponds to the second lens group) is placed behind the microlens array ML2, ML2 and L2 cause ML to be formed.
The light from the incident-side focal plane of No. 2 (that is, the outgoing plane of ML1) is superposed on the outgoing-side focal plane of L2.
In the figure, in order to illustrate a part thereof, it is schematically shown that lights of arrows B and B are inverted via L2 and overlap with one image (shown by an arrow C).

Since ML1 is located on the image plane of the LD emitter, the light from all the emitters is
All are overlapped once at the position of ML1, further divided by ML1, and then again overlapped by ML2 and L2. Therefore, on the exit-side focal plane of L2, the superimposed images after division are finally obtained for all the emitters.

Next, in the y plane, the LD emitter image can be formed on the image plane ML1 via L1, but in the LD array bar, all the LDs are arranged in a straight line extending in the x direction. Therefore, for the image of each LD, M
It is focused on one point on L1. And that one point is ML
Due to 2 and L2, the light is focused on one point on the final image plane (focal plane on the exit side of L2).

In the configuration of FIG. 4, the light from each emitter of the LD array bar has a linear image formed on the final image plane after the division, but this image shows the rays from all the emitters. With overlapping
When looking at the light from one emitter, it is the result of superimposing the light rays from each of the plurality of divided parts (see the description in FIGS. 1 and 2). Therefore, the uniformity is improved as compared with the conventional configuration. That is, FIG.
In the configuration shown in (1), since the images of different emitters are simply superposed, an averaged intensity distribution of all the emitters will be obtained. However, the intensity distribution for each emitter is generally high in the central part and low in the hem (peripheral part), so simply superimposing all emitter images from the central part to the peripheral part. It often causes a lack of strength at the hem of the toe.

On the other hand, as described above, by performing composition by dividing and superimposing each emitter, even if there is only one emitter, the effect of averaging the intensity distribution can be obtained. Therefore, as the number of emitters increases, the effect is further exhibited, and as a result, uniform light can be obtained as the final illumination light (linear illumination light). If the GLV is placed on the final image plane, the semiconductor laser array can uniformly illuminate (the linear region of) the GLV. Of course, in order to match the size of the illumination area (linear area) of the GLV with the size of the combined emitter image, the focal length of the collimator lens,
It is necessary to appropriately set various parameters in optical design including the structures of the microlens arrays ML1 and ML2 (element shapes, arrangement periods, etc.).

Further, in order to adjust the magnifications in the x-plane and the y-plane to the illumination area, a cylindrical lens having a curvature in the y-plane is used to obtain a desired illumination area width in the surface. It should be focused so that it can be collected. In this case, the focal position in the x-plane and the focal position in the y-plane are displaced, but the image is magnified with an extremely large magnification in the x-plane, so that the light is almost parallel light. . Therefore, G
It does not hinder the illumination optical system for the LV.

In the above description, for each emitter L
Although the near-field image of the exit end surface of D is spatially divided by the lens array and the conjugate image of the exit end obtained by superposing them is projected on the illumination surface (final image plane), as shown in FIG.
In, the emission end face of the LD, the emission side focal plane of L1, and the final image plane are in a conjugate relationship. ), But not limited to this, a similar configuration can be realized for the far-field image of the emission end face of each emitter.

FIG. 5 shows a configuration example 3 of a splitting / combining optical system conjugate with a light source and a pupil, in which the arrangement in the x plane is shown on the upper side, and the arrangement in the y plane is shown on the lower side. Is.

First, in the x-plane, for the LD array bar (the number of LDs is 3 for simplification), the same collimating lens 2 (2f, 2f) as in FIG. 4 is used.
s) is provided, the lens and the first lens group G1
An image of the emitter is formed on the focal plane on the exit side of L2 by (lenses L1 and L2). The exit-side focal plane of the first lens group G1 has a second lens group G2 (microlens array ML).
1, ML2). First lens group G1
The exit-side focal plane of is also the incident-side focal plane of the second lens group G2.

The focal plane on the exit side of the second lens group G2 coincides with the focal plane on the entrance side of the third lens group (L3, L4).

The light from the LD array bar is collimated by 2f and 2s, but the exit side focal plane of the collimating lens 2 is relayed and the intermediate plane of the second lens group G2 (in the figure) is relayed to the focal plane. A vertical line indicated by an alternate long and short dash line), and the emission-side focal planes of the third lens group G3 have a conjugate relationship with each other. Therefore, on the exit side focal plane of the third lens group G3, L
The far-field image for each emitter of the D array bar will be divided to obtain a superimposed image.

In the present example, in the y-plane, the lenses L1 and L2 forming the first lens group G1 are spherical lenses, and the same conjugate relationship as the above occurs, so that the focal point on the exit side of the third lens group G3. On the surface, a far-field image of each emitter of the LD array bar is divided and superposed.

The lens L1, which constitutes the first lens group G1,
When a cylindrical lens having power only in the x-plane is used in place of the spherical lens for L2, a configuration in which the conjugate relationship is inverted from that described above can be used, and in that case, in the case of Example 4 shown in FIG. Like The arrangement configuration in the x-plane is the same as in the case of FIG.

In the y-plane, the lenses L1cy and L2cy forming the first lens group G1 are shown as vertically long rectangles, and have no power in the plane.

Due to the structure in which the conjugate relationship is inverted, an image obtained by dividing and superimposing the near-field images of the respective emitters of the LD array bar is generated on the emission side focal plane of the third lens group G3.

In either of the configurations shown in FIGS. 5 and 6, a beam expander or a cylindrical lens is appropriately used at the rear of the third lens group G3 to match the combined image of the emitter with the shape and size of the illumination area. However, the focal plane can be brought to the illumination plane and matched.

FIG. 7A shows a configuration example (in the x plane) of the beam expander. In this figure, the beam expander 5 is composed of two lenses 6 and 7, and its incident side focal plane Si is set so as to coincide with the emitting side focal plane of the third lens group G3. An illumination object (illumination target) is placed on the focal plane So. If the incident-side focal plane of the beam expander is conjugate with the near-field image of the LD emitter, a relay image of the near-field image is generated on the exit-side focal plane of the beam expander. If the incident side focal plane of the beam expander is conjugate with the far-field image of the LD emitter, a relay image of the far-field image is generated on the exit-side focal plane of the beam expander.

Furthermore, if a cylindrical lens is added to the exit side of the third lens group, even if the entrance side focal plane of the beam expander is conjugate with the far-field image of the LD emitter, the exit side focal plane of the beam expander is A relay image of the far-field image is generated.

In the structure described above, the LDW is combined with the split-wave system from the first lens group to the second lens group and the third lens group (further including the cylindrical lens). Therefore, a one-dimensional illumination system (that is, an optical system that illuminates a linear region) can be configured with various conjugate relationships.

The x-plane is roughly classified into the following two relay methods and modes.

1. 1. A mode in which the near-field images of the respective emitters are divided and combined and relayed to the emission side focal plane of the second lens (or lens group). A mode in which the far-field images of the respective emitters are divided and combined and relayed to the emission side focal plane of the second lens (or lens group).

There are also two relay methods and configurations for the y-plane.

A. Mode in which the near-field image of each emitter is relayed to the emission side focal plane of the second lens (or lens group) B. A form in which the far-field image of each emitter is relayed to the emission side focal plane of the second lens (or lens group).

Any form may be combined, but linear uniform illumination light can be realized by using a plurality of cylindrical lenses.

In the application to the illumination optical system for GLV, schlieren filtering is performed by x
It is desirable that the light emission side is telecentric in the plane. That is, what is a problem in performing the Schlieren filtering is the incident angle of the light beam on the GLV.
Since the position of the light beam on the Schlieren filter depends on the incident angle of the light beam to the GLV, if the angle in the x plane can be limited, the contrast of the displayed image can be increased. Then, in order to perform the angle limitation, when the GLV (the illumination area thereof) is used as the image plane, a diaphragm may be placed on the surface which is the pupil plane. This is the third
It is the pupil plane of the lens group or the exit side focal plane of the second lens group. Therefore, if a diaphragm for limiting the light flux in the x-plane is arranged at this position, the incident angle of the light beam can be limited.
The diaphragm may be of a fixed type, a variable diaphragm, or a replaceable diaphragm.

Considering the viewing angle of the second lens group, it is desirable that the incident light on the microlens be as vertical as possible. That is, the light rays incident on the adjacent lens elements in the microlens array become stray light and cause a decrease in light utilization efficiency. Further, regarding the ray finally reaching the GLV, it is desirable that the incident state is vertical incidence or an incident state as close as possible to this for Schlieren filtering. For that purpose, the light emitted from the first lens group and the second lens group may be telecentric.

In the configurations shown in FIGS. 5 and 6, an example of the lens groups G1 to G3 including a plurality of lenses is shown, but this is merely an example, and as will be described later, for example, a microlens array. Can be made of a single member, and lens elements can be formed on the entrance surface side and the exit surface side, respectively, and various other embodiments are possible.

[0067]

EXAMPLE FIGS. 8 to 14 show lens arrangements for a first design example 8 of an illuminating device. In this example, a near-field image of an LD is divided in the x plane shown in FIG. The two focal planes on the exit side of the second lens group are conjugate with the near-field image of the LD.

FIG. 9 shows the arrangement in the y plane, and FIG.
Is the first group 9 (L1, L2), FIG. 11 is the microlens array ML, FIG. 12 is the second group 10 (L3, L4), FIG.
Shows enlarged views of the third group 11 (L5, L6, L7), respectively.

Specific values (unit: mm), materials, etc. are as shown in the table below.

[0070]

[Table 1]

In the above table, the added (x) and (y) indicate that the cylindrical lens has a curvature in the x-plane and in the y-plane.

The surface number is defined so that the number increases as the distance from the LD array bar side increases.

The third surface (surface number 3) marked with "(*)" in the above table is an aspherical cylindrical lens surface, and x
3D Cartesian coordinate system consisting of axes, y-axis and z-axis (the above-mentioned x-plane,
Different from the definition of the y-plane. ), "R ² = x ² +
y ² ”, it is represented by the following formula.

[0074]

[Equation 1]

Here, "k" indicates the curvature, and "cc +"
1 ”indicates the conic coefficient, and“ a _i ”(i = 4,6,8,10,1
2) is the aspherical coefficient. The coefficient values are as follows.

[0076] _{k = -1.3373 cc = -0.845963 a 4} = -0.130355 a 6 = -0.242383 a 8 = 0.527896 a 10 = -1.191043 a 12 = -0.952948

Further, a microlens array (surface number 1
Each of the elements (0, 11) has a size of 0.1 mm × 0.1 mm when viewed from the optical axis direction, and 30 or more elements are arranged in the x-plane and 1 or more elements are arranged in the y-plane. Further, it has an integrated structure in which lenses are formed on both surfaces of the glass base material.

This design example has the same structure as that in FIG. 6 in the x plane.

As the light source, there is used an LD array bar in which LDs having a wide area of 60 μm and having a pitch of 400 μm are arranged in parallel in the x direction.

The collimating lenses having surface numbers 2 to 5 are y
Direction cylindrical lens and x direction cylindrical lens array (element arrangement period is set to 400 μm, which is the same as the above LD). By independently collimating in the x direction and the y direction, the astigmatism of the LD in the broad area can be suppressed.

The emitter image of the LD array bar passes through an image side telecentric cylindrical lens (L1 and L2, which have a curvature only in the x plane),
It is formed on the image-side focal plane of the microlens array (plane numbers 10 and 11). In addition, the formation pitch of the microlens is 1
It is set to 00 μm. Further, in order to suppress vignetting in the microlens and control the propagation direction of the light rays thereafter, it is ideal that the first group is telecentric. In this example, since a cylindrical lens having a curvature in the x-plane is used, an emitter image is generated on the image-side focal plane of the microlens array in the y-plane. By doing so, since the condensing portion is not formed in the lens, it is possible to avoid damage to the glass (glass material) by the high-power laser light.

The second group (L3, L4) is also basically telecentric, and the principal ray for each incident angle of the emitted light beam is emitted substantially parallel to the optical axis. As described above, in the illumination optical system related to GLV, it is necessary to separate the diffracted light generated in GLV by schlieren filtering. Therefore, if the incident light beam angle is not sufficiently controlled, the contrast may be deteriorated. Therefore,
Also in the second group, it is effective to control the ray angle by a telecentric system.

The third group (L5 to L7) is a beam expander and is telecentric on both sides, so that the beam is expanded. This is irradiated onto (on the linear region of) the GLV by the condensing cylindrical lens L8.

FIG. 14 is a schematic view showing a configuration example 12 almost similar to the above-mentioned configuration for easy understanding, showing the arrangement in the y plane on the upper side and the x plane in the lower side. Shows the arrangement in. The number of elements in the microlens array can be arbitrarily designed, and is therefore shown conceptually in the figure. The total length is about 390 to 400 mm.

FIGS. 15 to 19 show the lens arrangement for the second design example 13 of the illuminating device.
In this example, the near-field image of the LD is divided and combined in the x-plane shown in FIG. 15, and the exit-side focal plane of the second lens group is conjugate with the near-field image of the LD in the x-plane and the y-plane. .

FIG. 16 shows the arrangement in the y plane, and FIG.
7 is the first group 14 (I-L1 to L4), FIG. 18 is the microlens arrays ML1 and ML2 (curvature of the microlens array is exaggerated for ease of viewing) and the second group 15 (II). -L1 to L4), FIG. 19 shows the third group 16 (I
II-L1 to L4) and an enlarged view of GLV, respectively.

Specific values (unit: mm), materials, etc. are as shown in the table below.

[0088]

[Table 2]

The meanings of (x) and (y) in the above table and the surface numbers are as described above.

Further, the third surface (surface number 3) is an aspherical cylindrical lens surface, and the same collimating lens as in the first design example is used.

In this example, the microlens array 1 (surface numbers 14 and 15) and the microlens array 2 (surface number 1) are used.
6 sheets, 17) are used. For each of these lens elements, 0.25 mm × when viewed from the optical axis direction
The size is 0.25 mm, and eight or more pieces are arranged in the x-plane and one or more pieces are arranged in the y-plane. In other words, a lens array base material having microlenses formed on one surface at an array period of 0.25 mm is used.

In the first design example described above, a cylindrical lens is used for the first group. However, in the case of a cylindrical lens, it does not have rotational symmetry about the optical axis, so that the optical axis is the center. You have to adjust the rotation. Therefore, in the second design example, a lens (rotating lens) having rotational symmetry around the optical axis is used. This has the same configuration as in FIG.

The first group and the second group are (emission side) telecentric lens systems as in the first design example. In this example, in order to improve the telecentricity,
The number of components is increasing for each lens group.

Regarding the light source and the collimating lens,
This is the same as the case of the first design example.

20 and 21 show the lens arrangement for the third design example 17 relating to the lighting device.
In this example, the far-field image of the LD is divided and combined in the x-plane shown in FIG. 20, and the exit-side focal plane of the second lens group is conjugate with the far-field image of the LD in the x-plane. Note that FIG.
Indicates the arrangement in the y-plane.

Specific values (unit: mm), materials, etc. are as shown in the table below.

[0097]

[Table 3]

The meanings of (x) and (y) in the above table and the surface numbers are as described above.

Further, the third surface (surface number 3) is an aspherical cylindrical lens surface, and the same collimating lens as in the first design example is used.

Two microlens arrays 1 (surface numbers 10 and 11) and a microlens array 2 (surface numbers 12 and 13) are used as the microlens array. Regarding each of these elements, 0.
It has a size of 1 mm x 0.1 mm and is 3 in the x-plane.
Zero or more and one or more are arranged in the y-plane.

The second group of surface numbers 14 to 21 constitutes a relay system, and the third group of surface numbers 22 to 27 constitutes an expansion system.

In this example, telecentric Koehler illumination is used in the x-plane, and the irradiation surface is conjugate with the far-field image of the LD. FIG. 7B shows an example in which lenses 19 and 20 are used as a configuration example 18 of the Koehler illumination system.

FIG. 22 shows an outline of the configuration of an application example 21 to an image display device using GLV.

The light from the laser light source 22 (LD array bar) is the intensity distribution conversion system 23 described above (the optical system described in the above design example, although it is typically shown by a single lens in the figure). ), And is applied to the spatial modulator 24 (for example, GLV). The light diffracted by the spatial modulator passes through the lens 25, the schlieren filter 26, and the lens 27, then passes through the projection lens system 28, reaches the galvanometer mirror 29, and further the screen 3
Reach 0. Illustration and description of the drive control means such as the GLV and the galvanometer mirror are omitted.

Therefore, according to the above configuration, it is possible to obtain uniform illumination by using an inexpensive semiconductor laser array and to realize it with high efficiency. For example, by applying the above-mentioned illumination device to an image display device using a one-dimensional spatial modulator such as GLV, it is possible to realize a laser display or the like capable of displaying a high-quality image having excellent color reproducibility.

[0106]

As is apparent from the above description, according to the first aspect of the invention, the laser light from the parallelized light source is used as the first lens array (or lens array group).
By collimating with, spatially dividing the combined image by the second lens array (or lens array group), and then overlapping again, it is possible to obtain illumination light with a uniform intensity distribution. Higher efficiency is possible.

According to the second aspect of the present invention, it is possible to narrow down the light rays to the linear region by using only one cylindrical lens, which is advantageous in terms of cost reduction.

According to the third aspect of the invention, the incident light on the second lens array (or lens array group) is made to enter vertically, and it is possible to prevent stray light at the lens element and deterioration of light utilization efficiency. .

According to the inventions of claims 4 and 5,
Since the configuration can be selected according to the design of the parallelized laser light source, the degree of freedom in design is improved.

According to the invention of claim 6, since lens arrays of various forms can be used, it is possible to increase the degree of freedom in design and method.

According to the invention of claim 7, it is possible to limit the incident angle of the light beam to the illumination surface within a certain range. Therefore, for example, the angle range of the diffracting direction of the incident light beam is set as in GLV. It is suitable when using a spatial modulator that needs to be sufficiently narrow.

In the invention according to claim 8, the exit side telecentricity of the first lens (or lens group) is effective for suppressing vignetting in the second lens array (or lens array group) and for controlling light rays. It is valid. Further, the exit side telecentricity of the second lens (or lens group) is effective in controlling (or limiting) the incident angle of the light ray on the illumination surface.

According to the ninth, tenth, and eleventh aspects of the invention, in application to an image display device using a spatial modulator such as GLV, high brightness and improvement in contrast and image quality are realized. Therefore, it is suitable for high quality.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of division and superposition regarding a Gaussian beam.

FIG. 2 is an explanatory diagram of division and superposition regarding irregular distribution.

FIG. 3 is an explanatory diagram of a configuration using a parallelized light source and a microlens array.

FIG. 4 is a diagram showing a configuration example of a light source-conjugated division / synthesis system.

FIG. 5 is a diagram showing a configuration example of a division / synthesis system conjugate with a light source and a pupil.

FIG. 6 is a diagram showing another example of a configuration of a division / synthesis system conjugate with a light source and a pupil.

FIG. 7 (A) shows a beam expander system,
The Koehler illumination system is shown in FIG.

FIG. 8 is a diagram for explaining the first design example together with FIGS. 9 to 14, and is a diagram showing an arrangement in the x-plane.

FIG. 9 is a diagram showing an arrangement in the y plane.

FIG. 10 is an enlarged view showing the configuration of the first group.

FIG. 11 is an enlarged view showing a microlens array.

FIG. 12 is an enlarged view showing a configuration of a second group.

FIG. 13 is an enlarged view showing the configuration of a third group.

FIG. 14 is a diagram for explaining an example of lens arrangement.

FIG. 15 is a diagram for explaining the second design example together with FIGS. 16 to 19, and this diagram is a diagram showing an arrangement in the x-plane.

FIG. 16 is a diagram showing an arrangement in the y plane.

FIG. 17 is an enlarged view showing the configuration of the first group.

FIG. 18 is an enlarged view showing the configurations of a microlens array and a second group.

FIG. 19 is an enlarged view showing a configuration of a third group.

20 is a diagram for explaining the third design example together with FIG. 21, and this diagram is a diagram showing an arrangement in the x-plane.

FIG. 21 is a diagram showing an arrangement in the y-plane.

FIG. 22 is a diagram schematically showing a configuration example of an image display device.

FIG. 23 is a diagram for explaining a Schlieren filter optical system.

FIG. 24 is an explanatory diagram showing a conventional configuration example.

[Explanation of symbols]

1 ... Parallelized light source, 2s ... 1st lens array, 5 ... 3rd lens group, 8, 12, 13, 17 ... Illumination device, 9, 1
4 ... 1st lens group, 10, 15 ... 2nd lens group, 1
1, 16 ... Third lens group, 21 ... Image display device, 24
... Spatial modulator, L1 ... First lens, G1 ... First lens group, ML ... Second lens array, ML1, ML2 ... Second lens array group, G2 ... Second lens array group, L
2 ... Second lens group, L8 ... Cylindrical lens

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H052 BA02 BA07 BA09 BA11                 2H091 FA07X FA07Z FA14Z FA26X                       FA26Z FA29X FA29Z FA41X                       FA41Z KA01 LA16 LA18                       MA07

Claims (11)

[Claims] 1. An illumination device provided with a laser light source, which is configured to obtain a uniform intensity distribution by using laser light from the parallelized light source, for collimating the parallelized light source. While arranging the first lens array or lens array group of
Combining the collimated light rays with a first lens or lens group, and further arranging a second lens array or lens array group to spatially divide the light rays before the second lens or lens An illuminating device equipped with a laser light source, characterized in that they are superposed by a group and projected onto an illumination surface through a third lens or a lens group. 2. An illumination device provided with the laser light source according to claim 1, wherein a cylindrical lens is arranged on the emission side of the third lens or lens group to illuminate a linear region. An illumination device equipped with a laser light source characterized by the above. 3. An illumination device provided with a laser light source according to claim 1, wherein an optical system which is telecentric on the exit side in at least one plane including the optical axis is used as the third lens or lens group. An illumination device equipped with a laser light source characterized by the above. 4. The illumination device provided with the laser light source according to claim 3, wherein the illumination surface and the light source surface are in a positional relationship of a conjugate image optically in at least one plane including an optical axis. A lighting device equipped with a characteristic laser light source. 5. The illuminating device provided with the laser light source according to claim 3, wherein the illumination plane and the pupil plane of the light source are in a positional relationship of a conjugate image optically in at least one plane including the optical axis. An illumination device equipped with a laser light source characterized by the above. 6. An illumination device provided with the laser light source according to claim 1, wherein the first lens array or the second lens array is a spherical lens array, a cylindrical lens array, a gradient index lens array, or an optical equivalent thereto. An illuminator equipped with a laser light source, characterized by using a diffractive optical element having a mechanical effect. 7. An illuminating device provided with the laser light source according to claim 1, wherein the focal plane on the emission side of the second lens array or the lens array group or on the plane in the third lens group which is conjugate with the variable focal plane. Alternatively, an illuminating device equipped with a laser light source, characterized in that a fixed diaphragm is arranged to limit a light beam incident angle on an illuminating surface. 8. An illumination device provided with the laser light source according to claim 1, wherein the first lens or the lens group or the second lens or the lens group has an emission side in at least one plane including an optical axis. An illumination device equipped with a laser light source, which uses a telecentric optical system. 9. An illuminating device configured to obtain a uniform intensity distribution by using laser beams from parallel light sources, and an image display device using a spatial modulator illuminated by the illuminating device. A first lens array or a lens array group for collimating the parallelized light sources is arranged, and
The collimated light rays are combined by the first lens or lens group, the second lens array or lens array group is further arranged to spatially divide the light, and then the second lens or lens group is used for superimposition. The image display device is characterized in that projection is performed on the illumination surface of the spatial modulator by a third lens or a lens group. 10. The image display device according to claim 9, wherein a one-dimensional spatial modulator is used as the spatial modulator. 11. The image display device according to claim 10, wherein a grating light valve is used as the one-dimensional spatial modulator.