JP2008147451A - Light source device for lighting and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device for lighting which uses a coherent light source and capable of suppressing the effect of speckle with a simple configuration. <P>SOLUTION: In a coherent light source 2 consisting of a plurality of light emitting points, independent of each other, a plurality of coherent beams 3 emitted from the light emitting points are sufficiently multiplexed by providing a free propagation space 4 for reduced coherence as the entire light source, by utilizing the fact that the coherent beams 3 emitted from the light emitting points are in incoherent relationship each other. Using a light source device 1a for lighting, the effect of speckle can be reduced even with a coherent light source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination light source device using a coherent light source, and more particularly to an illumination light source device that reduces speckle noise caused by coherence of a light source and an image display device using the illumination light source device.

  In recent years, many examples using lasers as light sources of optical image display devices have been reported. In general, light emitted from a laser has high directivity, so that the light use efficiency is expected to be improved, and the monochromaticity can realize a wide color reproduction region required in an image display device. Therefore, it is considered useful as a light source for illumination. On the other hand, since laser light has high coherence, when a laser is used as a light source of an image display device, there is a problem that a spotted pattern caused by light interference called speckle noise occurs on the image plane. This is because the light bulb, the element of the projection optical system, or the minute unevenness present on the screen causes the phase of each light beam passing through different points in the element plane to be shifted by an amount corresponding to the unevenness and to be coherent with each other. This is because these light beams form interference fringes on the image plane. Since the surface accuracy of these elements is finite, the influence of speckle noise is always a problem when a light source with high coherence is used. With recent advances in laser technology, semiconductor lasers, etc. that are small, high output, and have good beam quality are being actively developed, and it is expected that opportunities for lasers to be used as light sources for image display devices will increase in the future. Therefore, it is necessary to establish a speckle noise suppression method.

  In order to solve the problem of speckle, conventionally, a method using a rotating diffusion plate has been widely used. Since there are complex irregularities on the surface of the diffusion plate, a phase shift occurs between the light beams transmitted through different points of the diffusion plate. Therefore, when the diffuser plate is rotated, the interference fringe pattern, that is, the speckle shape, changes in a complex manner along the time axis, but the observed value of the receiver is the integrated value of the information captured within the response speed. Therefore, when the diffusion plate is rotated sufficiently faster than the response speed, the light intensity distribution recognized by the light receiver becomes almost uniform. That is, the influence of speckle reflected in the human eye can be reduced by rotating the diffusion plate at a speed faster than the response speed of the human eye that is the light receiver. However, since the diffusing plate has a light diffusing action, the light after passing through the diffusing plate has a divergence angle, thus causing a loss of light intensity. In addition, using a movable object such as a rotating diffusion plate requires a drive circuit and its power supply, and causes problems such as a decrease in reliability and noise.

  As other methods, a method using a microlens array in which a plurality of microlenses are arranged (for example, Patent Document 1) or a method using a fiber bundle in which a plurality of optical fibers having different lengths are bundled (for example, Patent Document 2). ) Has been proposed. In these methods, the light emitted from the laser is divided into a plurality of light beams using these elements, and the difference in optical distance between the light beams is made large relative to the coherence distance of the light, thereby obtaining those light beams. Since the luminous fluxes are incoherent with each other, the coherence of the entire light source can be reduced. However, using a microlens array or a plurality of fibers to divide light causes a decrease in light utilization efficiency, and using a plurality of optical fibers is problematic in terms of cost.

JP 2000-268603 A (page 4, FIG. 1) Japanese Patent Laid-Open No. 11-326653 (page 7, FIG. 1)

  As described above, the conventional speckle reduction method has problems such as a decrease in reliability and noise due to the use of a movable mechanism, or light utilization efficiency and cost due to the use of a microelement or a plurality of elements. ing.

  The present invention has been made in view of the above, and in an illumination device using a coherent light source, an illumination light source device capable of reducing speckle noise with a simple configuration and an image display using the illumination light source device The purpose is to obtain a device.

  In order to solve the above-described problems and achieve the object, the present invention includes a coherent light source having a plurality of emission points for emitting coherent light, and an optical means for receiving a plurality of coherent lights from the coherent light source. In the illumination light source device provided, the distance between the coherent light source and the optical means is optically set to be equal to or longer than an optical propagation distance for superimposing light of at least adjacent light emitting points. In the present invention, light emitted from a plurality of light emitting points in the light source is superposed on light emitted from a plurality of light emitting points in the light source by utilizing the fact that the light emitted from different independent light emitting points has low coherence. The coherence of the entire light source is lowered by superimposing more than the optical propagation distance, and the superimposed light is used as a new light source.

  According to the present invention, speckle noise is reduced and a high quality image can be obtained.

  Embodiments of an illumination light source device and an image display device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 shows a configuration diagram of an illumination device using the illumination light source device in the first embodiment. The illuminating device 1 of this Embodiment 1 is comprised from the light source device 1a for illumination, and the illumination optical system 1b.

  The illumination light source device 1a includes a semiconductor laser 2 having a plurality of light emitting points as a coherent light source, a free propagation space 4 for superimposing a plurality of coherent lights 3 emitted from the plurality of light emitting points of the semiconductor laser 2, and this free light. A collimating lens 5 and a condensing lens 6 are provided for condensing the low-coherent light obtained by superposition in the propagation space 4.

  The illumination optical system 1b is an illumination composed of an integrator rod 7 that makes the spatial intensity distribution of the light uniform by allowing the laser light collected by the condenser lens 6 to enter and propagate through the inside, and a lens or mirror. An optical system 8 and a light valve 9 such as a liquid crystal panel or a DMD (digital micromirror device) as a modulation element that spatially modulates illuminated light and gives an image signal are provided. A projection optical system (not shown) for enlarging and projecting the light emitted from the light valve 9 onto a screen for enlarging and projecting, and a display unit (not shown) such as a screen for projecting the light from the projection optical system; Further, an image display device such as an image projection device can be configured.

  As shown in FIG. 2, the semiconductor laser 2 generally has a configuration in which a plurality of light emitting points 10 are arranged in a line at equal intervals, and laser light 11 having a divergence angle is emitted from each light emitting point 10. In the present embodiment, the number of light emitting points 10 is ten, which are arranged on a straight line at an interval a of 300 μm, and the half-value half angle α of the divergence angle of the laser light emitted from each light emitting point 10 is about 5 degrees. is there. Each of the laser beams 11 emitted from the respective light emitting points 10 has no coherence between them, but the spatial coherence of the laser beams 11 emitted from the respective light emitting points 10 is very high, so that it is used as a light source as it is. The problem of speckle noise due to the interference of laser light occurs.

  In the present embodiment, laser light emitted from a plurality of different light emitting points 10 is collimated lens 5 which is an optical element into which laser light emitted from a space immediately after the emission, that is, semiconductor laser 2 and light emitting point 10 is directly incident. In the space between them, they are overlapped with each other to reduce spatial coherence, and the speckle noise is reduced by using a synthetic laser beam having low coherence as a light source.

Hereinafter, the principle of reducing the coherence of laser light by superimposing light emitted from a plurality of light emitting points will be described. At the spatial position r of the irradiated surface irradiated with light, two lights having a relationship of phase difference Δφa (r) expressed by a function of the position r as shown by the equations (1) and (2),
A (r, t) = u · exp (iφa (r, t)) (1)
A ′ (r, t) = u · exp [i (φa (r, t) + Δφa (r))] (2)
Is in a coherent relationship, the intensity Ico (r) of the combined light of the two lights on the irradiated surface is expressed as an expression relating to the spatial coordinates of the irradiated surface as shown in Expression (3).
Ico (r) ∝ | A + A ′ | ² = 2u ² + 2u ² cos Δφa (r) (3)
On the other hand, when the two lights are in an incoherent relationship, the light intensity Iinco on the irradiated surface of the combined light is expressed by the following formula (4).
Iinco (r) ∝ | A | ² + | A ′ | ² = 2u ² (4)

  A graph of these equations is shown in FIG. As is clear from FIG. 3, the light intensity Iinco when two lights having an incoherent relationship are superimposed is constant regardless of the spatial position, that is, regardless of the amount of phase shift caused by the unevenness of the element. On the other hand, the light intensity Ico in the case where two lights having a coherent relationship are superimposed shows light and dark due to the difference in phase shift amount at different spatial positions.

  Based on these facts, a comparison is made between a case where laser beams emitted from n (n ≧ 2) light emitting points are used without being superimposed and a case where laser beams are sufficiently superimposed. At this time, it is assumed that the total power Itotal reaching the irradiated surface is equal in both cases.

  When used without superimposing the laser light of each light emitting point, the laser light emitted from each light emitting point is spatially scattered on the irradiated surface, and an arbitrary region on the irradiated surface is a laser of one light emitting point. It is illuminated only by light. In this region, the light beams emitted from one light emitting point and passing through different spatial positions of the elements have a coherent relationship with each other, and thus form a complex interference fringe. Therefore, as shown in the spatial intensity distribution Ispread shown in FIG. 4, a plurality of interference fringes resulting from the coherence of light emitted from each light emitting point are scattered on the irradiated surface.

  On the other hand, when laser beams emitted from n light emitting points are superimposed on each other and the combined light is used as a light source, all of the laser lights emitted from the respective light emitting points uniformly illuminate the irradiated surface. . That is, as shown in the spatial intensity distribution of FIG. 5, the intensity amplitude I1 of the interference fringes generated due to coherence with respect to any one light emitting point is small with respect to the entire intensity, and the light emitted from other light emitting points Are incoherent to each other, so that the light intensity distributions I1, I2,..., In are simply integrated, and the overall intensity distribution Ioverlap approaches a constant by averaging.

  In this way, even if the laser light emitted from each light emitting point is light with high coherence, the laser light emitted from a plurality of light emitting points having different phases and incoherent relations is sufficiently superimposed. By doing so, it becomes possible to reduce the coherence as a synthesized laser beam. Therefore, an illumination light source device including a coherent light source having a plurality of light emission points and an optical system for superimposing laser light emitted from these light emission points can be regarded as a low coherent light source device.

  In the illumination light source device according to the first embodiment, a free propagation space 4 is provided as an optical system for superimposing laser beams 11 emitted from a plurality of light emitting points 10. Since the laser light 11 emitted from each light emitting point 10 has a divergence angle, the diameter of each laser light 11 increases as the propagation distance increases, and the overlap with the light emitted from the adjacent light emitting points increases. Go. Therefore, low-coherent light can be created by applying a simple method of spatially propagating a predetermined optical distance to light emitted from a plurality of light emitting points. Since the laser beam 11 is superimposed in the free propagation space 4 immediately after the laser beam is emitted in the first embodiment, the divergence angle of the laser beam 11 is relatively large (in this embodiment, half-value). It is desirable to use a light emitting point having a light emission point of about 5 degrees in order to shorten the length of the free propagation space 4 and make the device compact.

  Here, let us consider the spatial propagation distance necessary to produce low-coherent light. The principle of coherence reduction is that laser beams emitted from different emission points are superimposed on each other, and therefore it is a necessary condition that laser beams emitted from at least adjacent emission points are superimposed.

That is, when the distance between the light emitting points is a, the half-value half angle of the divergence angle of the laser light 11 emitted from the light emitting point is α, and the optical propagation distance of the light is Ldis, the above-mentioned requirements regarding the spatial propagation distance are satisfied. The formula is expressed as follows:
Ldis ≧ a / (2 · tan α) (5)

  However, the spatial propagation distance of light defined by the above equation (5) is the minimum distance required to reduce coherence, and actually the number of light emitting points, the light intensity of the light source, and the light The required spatial propagation distance varies according to the conditions regarding components such as valves and screens. Therefore, it is required to evaluate speckle under each condition and determine an optimum spatial propagation distance. A predetermined material other than air may be provided in the space 4 immediately after the laser light emission of the semiconductor laser 2 in order to superimpose the laser light from the plurality of light emitting points 10.

  In addition, the following method is also proposed as a method for realizing the spatial propagation distance defined above in a more compact space.

  FIG. 6 shows a configuration diagram of the illuminating device 12 including two parallel plates 15 and 16 each having a reflecting surface for ensuring a space propagation distance. The illumination device 12 includes an illumination light source device 12a and an illumination optical system 12b.

  The coherent light 14 emitted from a plurality of light emitting points of the semiconductor laser 13 travels between the mirrors 15 and 16 arranged in parallel while repeating reflection, and is emitted from the emission surface 17. The light emitted from the exit surface 17 enters the illumination optical system 12b as in FIG. In FIG. 6, in order to ensure the space propagation distance for superimposing the laser light, not by a straight line as shown in FIG. Can do.

  In addition, as shown in FIG. 7, the same effect as that in FIG. 6 can be realized by providing two reflecting surfaces on two opposing surfaces of the columnar optical element 18. At this time, if the two reflecting surfaces are configured to utilize total reflection due to the difference in refractive index between the optical element 18 and the outside air, an efficient illumination light source device with low light loss can be obtained. It is possible to produce. Further, if a mirror coating is applied to the surfaces used as the two reflecting surfaces, the incident angle is not limited as in the case of using the total reflection, and a free layout becomes possible.

  Further, if the incident surface of the optical element 18 is perpendicular to the optical axis as shown in FIG. 7, reflection loss at the incident surface can be reduced. Furthermore, if a non-reflective coating is applied to the incident surface, the loss at the incident surface can be further reduced.

  In this way, the illumination light source device 1a provided with the free propagation space 4 satisfying the expression (5) or the illumination light source device 12a provided with the optical elements 15, 16 and 18 composed of two parallel reflecting surfaces facing each other. Is incorporated into the lighting device, and it is possible to provide a lighting device in which unevenness in brightness due to speckle noise is suppressed while taking advantage of the monochromaticity and high directivity of the laser.

  In the first embodiment, a semiconductor laser having a plurality of light emitting points is given as an example of a coherent light source. However, the present invention is not limited to this, and a surface emitting laser or a solid-state laser in which a beam is emitted in an array shape. Etc. may be used. In the first embodiment, each laser beam is also superimposed on the integrator rod 7, so that a slight reduction in coherence can be expected in the integrator rod 7. However, the original function of the integrator rod 7 is to make the spatial intensity distribution of light uniform, and in order to obtain a sufficient reduction in coherence only within the integrator rod 7, the rod length of the integrator rod 7 is increased. In this case, there is a practical problem in terms of an increase in optical loss and a reduction in compactness.

  As described above, according to the illumination light source device in the first embodiment, the light emitted from each light emitting point in the coherent light source propagates at least the optical distance that superimposes the light at the adjacent light emitting point, It is superimposed on light emitted from a plurality of adjacent light emitting points and having a low coherence relationship, and the coherence of the entire light source can be reduced with a simple configuration. At this time, the coherence decreases as the number of superposed light emitting points increases. In the case of the illumination light source device, the superimposed light can be regarded as a new light source having high directivity and monochromaticity but low coherence. For example, by incorporating the illumination light source device into an image display device, Speckle noise is reduced and a high quality image is obtained.

Embodiment 2. FIG.
FIG. 8 shows a configuration diagram of a lighting device using the lighting light source device in the second embodiment. In FIG. 8, the illumination device 19 includes an illumination light source device 19a and an illumination optical system 19b. The illumination light source device 19a includes a surface emitting laser 20 having a plurality of emission points as a coherent light source, an optical fiber 23 for superimposing and propagating a plurality of laser beams 21 emitted from the plurality of emission points of the surface emitting laser 20, and a laser. A condensing lens 22 that condenses the light 21 at the incident end of the optical fiber 23 is provided. The illumination optical system 19b also spatially distributes the illuminated light, an integrator rod 24 that makes the spatial intensity distribution of the light emitted from the optical fiber 23 uniform, an illumination optical system 25 that includes lenses and mirrors, and the like. A light valve 26 for modulating and forming an image is provided. A projection optical system (not shown) for enlarging and projecting the light emitted from the light valve 26 onto a screen for enlarging and projecting, and a display unit (not shown) such as a screen on which the light from the projection optical system is projected Further, an image display device such as an image projection device can be configured.

  In general, the surface emitting laser 20 has a plurality of light emitting points 30 arranged at almost equal intervals, and each light emitting point 30 emits laser light with very high coherence, a small light spread angle, and high directivity. The In the present embodiment, the number of light emitting points 30 is 11, which are arranged on a straight line at intervals of 150 μm, and the half-value half angle of the divergence angle of the laser light emitted from each light emitting point 30 is about 0.6 degrees. is there. Although such surface-emitting lasers have no coherence between them, the spatial coherence of laser light emitted from each light emitting point is very high, so speckle noise caused by laser light interference when used as it is as a light source. Problems occur.

  In the first embodiment, the method of generating the low coherent light by providing the free propagation space 4 for superimposing the laser light emitted from the plurality of light emitting points 10 has been described. In the second embodiment, a method of obtaining the same effect by providing the optical fiber 23 will be described.

  The operation in the second embodiment will be described. Laser light 21 emitted from a plurality of light emitting points 30 of the surface emitting laser 20 has a small divergence angle, and therefore enters the condenser lens 22 without overlapping each other and is coupled to the optical fiber 23. The coherent laser light incident on the optical fiber 23 propagates with a spread corresponding to the condensing angle of the condensing lens 22. Therefore, by securing the length of the optical fiber 23 at a predetermined distance or more, the internal laser light is sufficiently spread, and the laser lights emitted from the respective light emitting points overlap each other. As described in the first embodiment, the coherence of laser beams emitted from different light emission points is reduced by superimposing laser beams emitted from different emission points. Therefore, low-coherent light can also be produced by a method in which light emitted from a plurality of light emitting points is coupled to an optical fiber 23 having a predetermined length and propagated.

  Here, the length of the optical fiber required to realize this configuration is estimated. If the light at each light emitting point 30 spreads to the same size as the diameter of the fiber 23, the light at all the light emitting points is superimposed on the diameter of the optical fiber 23, and the light at the exit end of the optical fiber 23 is light with low coherence. It becomes. Since the laser light emitted from each of the 11 light emitting points is condensed by the same lens 22, the light incident on the outer side of the lens 22 has a larger incident angle to the optical fiber and the number of reflections in the core increases. The distance that the light propagates becomes longer with respect to the length of the optical fiber, and the beam diameter spreads faster. Conversely, the light incident on the center of the lens 22 has a slower beam diameter spread with respect to the length of the optical fiber. Therefore, the optical distance where the diameter of the laser light emitted from the light emitting point located on the optical axis spreads to the same extent as the diameter of the optical fiber is a condition of the optical distance necessary for superimposing all the light.

Therefore, paying attention to the light at the light emitting point located on the optical axis, the optical distance necessary for the light diameter to be equal to that of the optical fiber is derived. FIG. 9 is a conceptual diagram relating to the coupling of light to the optical fiber used in the illumination light source device. As shown in FIG. 9, when the half-value half angle of the spread angle of the laser light 27 emitted from the light emitting point on the optical axis in the optical fiber 28 is β and the core diameter of the optical fiber 28 is b, the laser light 27 is The optical fiber length Lfib necessary to expand to the same size as the core diameter of the optical fiber 28 is
Lfib ≧ b / (2 · tan β) (6)
It becomes.

  That is, even if each is a coherent laser beam, when the laser beam emitted from a plurality of light emitting points is coupled to an optical fiber having a length of Lfib or longer and propagated, the superposition obtained at the exit end of the optical fiber 28 The emitted laser light can be regarded as low-coherent light. The illumination light source device 19a obtained in this way, like the illumination light source device 1a of the first embodiment, emits light with low coherence while having characteristics such as monochromaticity and high directivity of a laser used as a light source. If it is possible to emit light and enter the illumination optical system 19b to be used in the illumination device, it is possible to provide an illumination device in which unevenness in brightness due to speckle noise is suppressed.

  Furthermore, since the light source device 19a for illumination increases the freedom degree regarding arrangement | positioning of an optical system by utilization of a fiber, it becomes possible to comprise a smaller apparatus. That is, when laser light with a small divergence angle is employed, when the free propagation space 4 is used as in Embodiment 1 in superimposing the laser light with such a small divergence angle, it is free to obtain low coherence light. The length of the propagation space 4 becomes long. On the other hand, in the second embodiment, since the laser light is superimposed by the bendable optical fiber 23, the space for superimposing the laser light may be increased even when the laser light having a small divergence angle is adopted. And contributes to downsizing of the device. Thus, this Embodiment 2 functions suitably, when a laser beam with a comparatively small divergence angle is employ | adopted.

  Further, according to the second embodiment, in addition to the speckle reduction effect by superimposing a plurality of laser beams, the laser beam propagating in the optical fiber has a disturbed wavefront, so that the coherence of the light further decreases, and the speckle reduction effect is achieved. Further increase.

  There are other effects obtained by using an optical fiber. Since the light propagating in the optical fiber travels while being totally reflected at the interface between the fiber core and the clad, the diameter of the light does not become larger than the core diameter, and the subsequent optical element can be miniaturized. Furthermore, since the fiber is strong against bending, it has flexibility in arrangement of the optical system, leading to reduction of the optical system.

  For example, by incorporating this lighting device 19 into an image display device, it is possible to reduce the size and size of an image display device that has high light use efficiency and a wide color reproduction area and has high image quality by reducing speckle noise. It becomes.

  In the second embodiment, a surface emitting laser is given as an example of a coherent light source having a plurality of light emitting points. However, the present invention is not limited to this, and for example, a solid laser or a plurality of lasers that emit a beam in an array form. A semiconductor laser or the like having a light emitting point may be used.

  In Embodiments 1 and 2, the integrator rod is used as an element for uniformizing the spatial light intensity distribution of the illumination optical system. However, the present invention is not limited to this, and for example, a microlens or the like Other elements for making the light intensity distribution uniform may be used.

  Further, in the second embodiment, the case where the optical fibers are arranged linearly has been described. However, the optical fiber may be bent (that is, provided with a predetermined curvature). In this case, the length of the optical fiber can be made shorter than arranging the optical fiber in a straight line. If it does so, the space which arrange | positions an optical fiber can be made small. Therefore, the lighting device can be reduced in size. In addition, what is necessary is just to set suitably conditions, such as a curvature when an optical fiber is bent, according to the specification etc. of the said illuminating device by experiment or simulation.

Embodiment 3 FIG.
In the third embodiment, a case where a semiconductor laser 45 in which a plurality of light emitting points 40 as shown in FIG. 10 are arranged in a two-dimensional matrix is considered. Using such a semiconductor laser 45, as shown in FIG. 1, it is assumed that a free propagation space 4 for superimposing laser light is provided in a space immediately after the laser light emission of the semiconductor laser. In this semiconductor laser 45, the half-value half angle αx of the divergence angle in the X direction of the laser light emitted from each light emitting point 40 is about 5 degrees, and the half value half angle αy of the divergence angle in the Y direction is about 20 degrees. is there. The interval between the light emitting points 40 in the X direction is ax, and the interval between the light emitting points 40 in the Y direction is ay.

  As described above, when the divergence angles and the emission point intervals in the X and Y directions are different, at least one of the X and Y directions has been described in order to superimpose laser beams emitted from adjacent emission points. It is necessary to satisfy Expression (5). Therefore, in such a case, when the minimum required distance in the X direction obtained from Equation (5) is Ldisx and the minimum required distance in the Y direction is Ldisy, the shorter of Ldisx and Ldisy Then, the distance of the free propagation space 4 for superimposing the laser beam over the selected length is set.

  Further, as described above, when the divergence angle and the emission point interval in the X and Y directions are different, the coherence after passing through the free propagation space 4 having a predetermined length may be different in the X and Y directions. high. Since it is difficult to change the divergence angle of each light emitting point in the X and Y directions, the light emitting point intervals ax and ay in the X and Y directions are appropriately changed and set so as to pass through the free propagation space 4 having a predetermined length. The coherence in the X and Y directions may be the same.

  As described above, the illumination light source device according to the present invention is useful for an illumination light source device using a laser as a coherent light source and an image display device using the illumination light source device.

It is a block diagram which shows the illuminating device by Embodiment 1. FIG. 3 is a conceptual diagram of low-coherence light generation according to Embodiment 1. FIG. It is a figure which shows the light intensity distribution with respect to the spatial position when two light beams are superimposed. It is a figure which shows the light intensity distribution with respect to the spatial position in the to-be-irradiated surface when the light inject | emitted from the several light emission point is not superimposed. It is a figure which shows the light intensity distribution with respect to the spatial position in the to-be-irradiated surface at the time of superimposing the light inject | emitted from the several light emission point. It is a block diagram which shows the illuminating device which provided the 2 parallel plate by Embodiment 1. FIG. It is a block diagram which shows the light source device for illumination which provided the optical element by Embodiment 1. FIG. It is a block diagram which shows the illuminating device by Embodiment 2. FIG. FIG. 6 is a conceptual diagram relating to the incidence of light on an optical fiber used in Embodiment 2. It is a top view which shows the light source device with which the several light emission point was arranged in matrix.

Explanation of symbols

1, 12, 19 Illumination device 1a, 12a, 19a Illumination light source device 1b, 12b, 19b Illumination optical system 2, 13 Coherent light source (semiconductor laser)
3, 14 Coherent light (laser light)
4 Free Propagation Space 5 Collimating Lens 6 Condensing Lens 7 Integrator Rod 8, 25 Illumination Optical System 9, 26 Light Valve 10 Light Emitting Point 11, 27 Laser Light 15 Optical Element (Mirror)
DESCRIPTION OF SYMBOLS 17 Outgoing surface 18 Optical element 20 Surface emitting laser 21 Laser light 22 Condensing lens 23 Optical fiber 24 Integrator rod 28 Optical fiber 30, 40 Light emitting point 45 Semiconductor laser

Claims (7)

In an illumination light source device comprising: a coherent light source having a plurality of emission points that emits coherent light; and an optical unit on which a plurality of coherent lights from the coherent light source are incident.
An illumination light source device characterized in that a distance between the coherent light source and the optical means is optically set to be equal to or greater than an optical propagation distance for superimposing light of at least adjacent light emitting points.   Ldis ≧ a / (2 · tan α) where a is the distance between the light emitting points, α is the half value half angle of the divergence angle of the coherent light emitted from the light emitting points, and Ldis is the optical propagation distance. The illumination light source device according to claim 1.   The light propagation material which can ensure the distance more than the said optical propagation distance between the said coherent light source and an optical means, and can permeate | transmit the said coherent light is arrange | positioned. The light source device for illumination as described. An optical element having two reflecting surfaces disposed so as to face each other between the coherent light source and the optical means;
3. The illumination light source according to claim 1, wherein a distance that the coherent light emitted from the coherent light source propagates while repeating reflection inside the optical element is equal to or longer than the optical propagation distance. 4. apparatus. A coherent light source having a plurality of emission points for emitting coherent light, an optical element for collecting the plurality of coherent light emitted from the coherent light source, and an optical fiber for transmitting the collected plurality of coherent lights in combination. With
When the optical fiber length is Lfib, the core diameter of the optical fiber is b, and the half-value half angle of the spread angle of each coherent light in the optical fiber is β, the length Lfib of the optical fiber is
Lfib ≧ b / (2 · tanβ)
An illumination light source device characterized by the above.   6. The coherent light source according to claim 1, wherein the coherent light source is a semiconductor laser having a plurality of light emitting points, a surface emitting laser, or a solid-state laser arranged in an array. Light source device for illumination. An illumination optical system that has the illumination light source device according to any one of claims 1 to 6 and outputs illumination light;
A light modulation element for controlling the illumination light incident from the illumination optical system to form an image;
A display unit for displaying light from the light modulation element;
An image display device comprising:

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