Abstract:
The present invention provides a microlens array including multiple microlenses arranged axially parallel to one another, wherein entrance surfaces of the microlenses on which light is incident are made of resin, and exit surfaces of the microlenses from which light exits are made of glass.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The entire disclosure including the specification, claims, drawings and abstract of Japanese Patent Application No. 2012-276802 filed on Dec. 19, 2012 is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a microlens array, a light intensity distribution uniformizing element having the same, and a projection apparatus including the light intensity distribution uniformizing element. 
         [0004]    2. Description of the Related Art 
         [0005]    Microlens arrays in which a large number of microlenses are arranged one-dimensionally or two dimensionally are known. For example, Japanese Patent Application Laid-Open No. 6-250002 discloses a method of manufacturing such microlens arrays. More specifically, a method of manufacturing microlens arrays by using optical patterning and dry etching is disclosed. With the microlenses, a light intensity distribution uniformizing element that uniformizes light intensity distribution can be formed, for example. 
         [0006]    In formation of a microlens array with glass, for example, it is difficult to form the entire surfaces of microlenses constituting the microlens array into an ideal lens shape owing to the required processing accuracy. In particular, it is difficult to form an ideal lens shape around boundaries between adjacent microlenses. Portions that are not in the ideal lens shape are ineffective portions that do not function as desirable lenses. The presence of the ineffective portions causes optical loss. The optical loss is greater as the ineffective portions are larger. 
         [0007]    Use of resin, for example, facilitates more accurate formation of microlens arrays than using glass. Resin, however, is more susceptible to thermal degradation than glass, for example. 
         [0008]    An object of the present invention is to provide a microlens array with reduced optical loss and less susceptible to degradation, a light intensity distribution uniformizing element having the same, and a projection apparatus including the light intensity distribution uniformizing element. 
       SUMMARY OF THE INVENTION 
       [0009]    According to an aspect of the present invention, there is provided a microlens array including multiple microlenses arranged axially parallel to one another, wherein 
         [0010]    entrance surfaces of the microlenses on which light is incident are made of resin, and 
         [0011]    exit surfaces of the microlenses from which light exits are made of glass. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The aforementioned object and further objects, features and advantages of the invention will become further apparent from the following detailed description as well as the accompanying drawings, in which: 
           [0013]      FIG. 1  is a schematic view of an example structure of a light intensity distribution uniformizing element according to a first embodiment; 
           [0014]      FIG. 2  is an explanatory view of an example structure of a microlens array according to the first embodiment; 
           [0015]      FIG. 3  is a schematic view of another example structure of a microlens array according to the first embodiment; 
           [0016]      FIG. 4  is a schematic block diagram illustrating an example configuration of a projector according to a second embodiment; and 
           [0017]      FIG. 5  is a schematic block diagram of an example of an optical system of the projector according to the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    Hereinafter, a best mode for carrying out the invention will be described by reference to the drawings. Although embodiments that will be described below involve various technical limitations which are preferred in carrying out the invention, the scope of invention is not at all limited to the following embodiments and illustrations made therein. 
       First Embodiment 
       [0019]    A first embodiment of the invention will be described with reference to the drawings.  FIG. 1  illustrates an outline of an example structure of a light intensity distribution uniformizing element  100  according to the present embodiment. The light intensity distribution uniformizing element  100  includes a microlens array  110  and a coupling lens  160 . The coupling lens  160  includes a first lens  162 , a second lens  164 , and a third lens  166 . 
         [0020]    The microlens array  110  includes multiple microlenses  112 . The microlenses  112  are arranged in an array on one plane in a state in which optical axes of the microlenses  112  are parallel. For example, the microlenses  112  are arranged in a rectangular grid pattern. 
         [0021]    The microlens array  110  according to the present embodiment includes a first microlens array  122  provided on the entrance side and a second microlens array  126  provided on the exit side. The first microlens array  122  is made of resin. The second microlens array  126  is made of glass. The first microlens array  122  includes multiple microlenses arranged in an array as a unit. Similarly, the second microlens array  126  includes multiple microlenses arranged in an array as a unit. The first microlens array  122  and the second microlens array  126  are bonded at an adhesive layer  129  with an adhesive for lenses, for example. 
         [0022]    The microlenses in the first microlens array  122  and the microlenses in the second microlens array  126  respectively correspond to each other. Thus, one microlens in the first microlens array  122  and one microlens in the second microlens array  126  form one microlens  112 . The lenses in the first microlens array  122  will be referred to as first microlenses  123 , and the lenses in the second microlens array  126  will be referred to as second microlenses  127 . Note that circles  180  in  FIG. 1  represent regions of ineffective portions that does not function as lenses as designed owing to limitations in the processing accuracy, for example. Thus, the ineffective portions are larger as the circles are larger. Regions other than those with the circles  180  are effective portions that function as lenses as designed. 
         [0023]    The first microlenses  123  are formed so that light beams incident on the first microlenses  123  enter the effective portions of the corresponding second microlenses  127  even if there are some manufacturing errors in the microlens array  126 . Specifically, the first microlenses  123  each focusing light into the middle of the corresponding second microlens  127  are formed on the entrance side of the first microlens array  122 . On the other hand, the second microlenses  127  are formed on the exit side of the second microlens array  126  so that pencils of rays each passing through one point on a first microlens  123  exit in parallel from the second microlens array  126 . In other words, the first microlenses  123  and the second microlenses  127  have shapes optically symmetrical to each other. Since, however, resin and glass have different refractive indices, the first microlenses  123  and the second microlenses  127  have slightly different radii of curvature. 
         [0024]    The functions of the light intensity distribution uniformizing element  100  including the microlens array  110  according to the present embodiment will be described. An optical path of parallel light entering the microlens array  110  including the first microlens array  122  and the second microlens array  126  will be as illustrated in  FIG. 2 . Specifically, the exiting direction of light passing through the microlens array  110  is determined depending on the position on each microlens  112  where the light enters. As a result, the pencils of rays exiting the microlens array  110  are in a shape corresponding to the arrangement of the microlenses, that is, a rectangular shape similar to that of pencils of rays emitted from a light source at infinity. 
         [0025]    In the present embodiment, as illustrated in  FIG. 1 , the coupling lens  160  is provided so as to focus light exiting the microlens array  110  onto an irradiation surface  170 . Light rays incident on the microlenses  112  of the microlens array  110  are emitted to a predetermined area of the irradiation surface  170 . As a result, the light intensity distribution at the irradiation surface  170  is a sum of intensity distributions of light rays exiting the microlenses. If the pitch of the microlenses  112  in the microlens array  110  is sufficiently small, the light intensity distribution at the irradiation surface  170  will be uniform independently of the light intensity distribution at the entrance surface of the microlens array  110 . 
         [0026]    As described above, the light intensity distribution uniformizing element  100  according to the present embodiment can make the light intensity distribution at the irradiation surface  170  uniform even when the intensity distribution of light incident on the light intensity distribution uniformizing element  100  is non-uniform. 
         [0027]    The microlens array  110  according to the present embodiment includes the first microlens array  122  made of resin and the second microlens array  126  made of glass. The reason why these arrays are combined is as follows. Use of resin as a material like the first microlens array  122  facilitates mold making, for example, and can thus make the shape of the microlenses accurate. As a result, the effective portions that function as lenses become larger and the ineffective portions that do not function as lenses because of shape distortion or the like. Use of resin, however, leads to susceptibility to performance degradation due to heat. In contrast, use of glass as a material like the second microlens array  126  causes less performance degradation. Accurate processing, however, is difficult and ineffective portions are thus likely to be larger. 
         [0028]    In the present embodiment, the ineffective portions of the first microlens array  122  are larger than the ineffective portions of the second microlens array  126  as shown by the circles  180  in  FIG. 1 . Thus, with the microlens array  110  of the present embodiment, light incident on the first microlens array  122  can be used in a higher proportion than in a case where the whole microlens array  110  is made of glass. 
         [0029]    The incident light focuses on the exit surface of the second microlens array  126 . The second microlens array  126  is thus likely to become hot around the exit surface. Hence, the second microlens array  126  is more affected by heat than the first microlens array  122 . In the present embodiment, the exit side of the microlens array  110  is formed of the second microlens array  126  made of glass, which makes the microlens array  110  less susceptible to thermal degradation than a case where the whole microlens array  110  is made of resin. Although the ineffective portions of the second microlens array  126  are larger than those of the first microlens array  122 , the ineffective portions do not transmit light. Hence, the size of the ineffective portions does not affect the performance of the microlens array  110 . 
         [0030]    As described above, resin having smaller ineffective portions is used for the entrance side and glass excellent in heat resistance is used for the exit side, which realizes the microlens array  110  with good light use efficiency and excellent durability. Since light is focused in the second microlens array  126  made of glass, the present embodiment produces particularly advantageous effects. Focusing of light in the second microlens array  126  is advantageous in that the influence of errors in positioning of the microlenses of the first microlens array  122  and the microlenses of the second microlens array  126  is smaller. 
         [0031]    Furthermore, since the first microlens array  122  and the second microlens array  126  are bonded to form the microlens array  110  as a unit, there is an advantage that the microlens array  110  can be easily treated when being mounted. 
         [0032]    In the present embodiment, the microlens array  110  includes the first microlens array  122  and the second microlens array  126  that are bonded to each other. Alternatively, however, the first microlens array  122  and the second microlens array  126  may be provided separately. In this case, a non-reflective coating film may be provided between the first microlens array  122  and the second microlens array  126  or the entrance surface of the second microlens array  126  may be coated with a non-reflective coating to prevent light exiting the first microlens array from being reflected by the entrance surface of the first microlens array. 
         [0033]    Furthermore, in the microlens array  110  illustrated in  FIG. 1 , the first microlens array  122  and the second microlens array  126  have substantially equal sizes. The ratio of the size of the first microlens array  122  to that of the second microlens array  126  may be any ratio. 
         [0034]    The microlens array  110  may thus be formed by placing a thin third microlens array  132  made of resin on a fourth microlens array  136  made of glass as illustrated in  FIG. 3 , for example. In this case, the microlens array  110  is produced by the following procedures, for example. First, the fourth microlens array  136  made of glass is formed similarly to common microlens arrays. Thereafter, the third microlens array  132  made of resin and designed to function similarly to the first microlenses  123  described above is formed on the entrance surface of the fourth microlens array  136 . For the third microlens array  132 , an ultraviolet curable resin or a thermosetting resin such as an epoxy resin is used. For the formation of the third microlens array  132 , technologies for forming aspherical lenses can be applied, for example. With such technologies, manufacture of the microlens array  110  according to the present embodiment is relatively easy. 
         [0035]    Although an example in which convexes are formed on the entrance surface of the third microlens array  136  is illustrated in  FIG. 3 , the entrance surface of the third microlens array  136  may be flat and only the coating layer  132  may have convexes functioning as lenses. 
         [0036]    The microlens array  110  included in the light intensity distribution uniformizing element  100  can be used in various applications other than the light intensity distribution uniformizing element similarly to other typical microlens arrays  110 . Although a case in which multiple microlenses  112  are arranged on a plane is presented in the present embodiment, the technologies of the present embodiment can also be applied to microlens array in which microlenses are arranged linearly such as in on row. 
       Second Embodiment 
       [0037]    A second embodiment will be described with reference to the drawings. The present embodiment is an embodiment of a projection apparatus in which the microlens array according to the first embodiment is used.  FIG. 4  illustrates an outline of an example configuration of the projector  10  that is a projection apparatus according to the present embodiment. The projector  10  is a digital light processing (DLP) (registered trademark) projector using a micromirror display device. The projector  10  includes an input unit  11 , an image converter  12 , a projection processor  13 , a micromirror device  14 , a light source unit  15 , a mirror  16 , a projector lens unit  17 , a CPU  18 , a main memory  19 , a program memory  20 , an operation unit  21 , an audio processor  22 , a speaker  23 , and a system bus SB. 
         [0038]    The input unit  11  includes terminals such as a pin jack (RCA) type video input terminal and a D-sub  15  type RGB input terminal, and receives analog image signals as input. The input unit  11  converts the input analog image signals of various standards into digital image signals. The input unit  11  outputs the digital image signals obtained by the conversion to the image converter  12  via the system bus SB. The input unit  11  is also provided with an HDMI (registered trademark) and the like, and can receive digital image signals as input in addition to analog image signals. Furthermore, the input unit  11  also receives audio signals that are analog or digital signals. The input unit  11  outputs the input audio signals to the audio processor  22 . 
         [0039]    The image converter  12  is also referred to as a scaler. The image converter  12  is connected to the system bus SB. The image converter  12  converts the input image data into image data of a predetermined format suitable for projection, and sends the converted data to the projection processor  13 . Where necessary, the image converter  12  sends image data on which symbols indicating various operation states for On Screen Display (OSD) as processed image data to the projection processor  13 . 
         [0040]    The light source unit  15  emits light rays of multiple colors including primary colors of red (R), green (G), and blue (B) under the control of the projection processor  13 . The light source unit  15  is configured to emit light rays of multiple colors sequentially on a time division basis. Light emitted by the light source unit  15  is totally reflected by the mirror  16  and incident on the micromirror device  14 . 
         [0041]    The micromirror device  14  includes multiple micromirrors arranged in an array like a digital micromirror device (DMD; registered trademark). Micromirrors are rapidly switched on and off to reflect light emitted by the light source unit  15  toward the projector lens unit  17  and away from the projector lens unit  17 . The micromirror device  14  has an array of micromirrors corresponding to WXGA (Wide eXtended Graphic Array) (1280 horizontal pixels×800 vertical pixels), for example. The micromirror device  14  forms an image with WXGA resolution, for example, by reflection at the micromirrors. The micromirror device  14  thus functions as a spatial light modulation device. 
         [0042]    The projection processor  13  is connected to the system bus SB, and drives the micromirror device  14  to display an image represented by image data sent from the image converter  12 . Thus, the projection processor  13  switches the micromirrors of the micromirror device  14  on and off. Note that the projection processor  13  rapidly drives the micromirror device  14  on a time division basis. The number of divisions per unit time is a number obtained by multiplying a frame rate according to a predetermined format, such as 60 [frames/second], the number of divisions for color components, and the number of gradations for display. The projection processor  13  also controls operation of the light source unit  15  to synchronize with the operation of the micromirror device  14 . Specifically, the projection processor  13  controls the operation of the light source unit  15  to divide frames into time slots and sequentially emit light of every color component for each frame. 
         [0043]    The projector lens unit  17  adjusts light guided by the micromirror device  14  to light for projection onto an object onto which projection is made such as a screen (not illustrated), for example. Thus, an optical image formed by light reflected by the micromirror device  14  is projected and displayed onto the screen via the projector lens unit  17 . 
         [0044]    The audio processor  22  is connected to the system bus SB and includes an audio source circuit such as a PCM audio source. The audio processor  22  drives the speaker  23  to emit amplified sound on the basis of analog audio data input from the input unit  11  or on the basis of a signal obtained by converting digital audio data provided at the projecting operation into analog data. The audio processor  22  also generates a beep sound or the like where necessary. The speaker  23  is a typical speaker that emits audio on the basis of a signal input from the audio processor  22 . 
         [0045]    The CPU  18  is connected to the system bus SB, and controls operation of the image converter  12 , the projection processor  13 , and the audio processor  22 . The CPU  18  is connected to the main memory  19  and the program memory  20 . The main memory  19  is an SRAM, for example. The main memory  19  functions as a working memory for the CPU  18 . The program memory  20  is an electrically rewritable nonvolatile memory. The program memory  20  stores operation programs to be executed by the CPU  18  and various format data. The CPU  18  is also connected to the operation unit  21 . The operation unit  21  includes a key operation unit provided on the body of the projector  10  and an infrared ray receiving unit configured to receive infrared light from a remote controller (not illustrated) exclusively for the projector  10 . The operation unit  21  outputs a key operation signal based on a key operation of the user at the key operation unit of the body or the remote controller to the CPU  18 . The CPU  18  controls the operation of the respective components of the projector  10  in response to user&#39;s instruction from the operation unit  21  by using the programs and data stored in the main memory  19  and the program memory  20 . 
         [0046]    The optical system of the projector  10  according to the present embodiment including the light source unit  15 , the mirror  16 , the micromirror device  14  and the projector lens unit  17  will be described with reference to  FIG. 5 . The light source unit  15  is provided with a laser light source unit  30  having semiconductor lasers (laser diodes: LD)  31  that are semiconductor light emitting devices configured to emit blue laser light as a light source. The LDs  31  are arranged in an array in the laser light source unit  30 . In the present embodiment, a total of 24 LDs  31  including 3 in row×8 in column are arranged in an array, for example. The blue laser rays emitted by the respective LDs  31  pass through collimator lenses  32  positioned for the respective LD  31  to become parallel rays, and are emitted from the laser light source unit  30 . 
         [0047]    Mirrors  33  are arranged like a staircase at positions facing the collimator lenses  32 . The laser rays emitted from the laser light source unit  30  are reflected by the mirrors  33  to changes the optical paths by 90 degrees. The laser rays reflected by the mirrors  33  are focused into beams. The pencil of light is thus emitted by the laser light source unit  30 . 
         [0048]    On the optical path of the beams, lenses  34  and  35  and a first dichroic mirror  36  are arranged. The laser rays reflected by the mirror  33  are converted to parallel beams by the lenses  34  and  35 , and are then incident on the first dichroic mirror  36 . The first dichroic mirror  36  transmits blue light and red light but reflects green light. On the optical path of blue light transmitted by the first dichroic mirror  36 , lenses  37  and  38  and a fluorescent wheel  39  are arranged. The blue light transmitted by the first dichroic mirror  36  is emitted to the fluorescent wheel  39  via the lenses  37  and  38 . 
         [0049]    The fluorescent wheel  39  has a disc-like shape. The fluorescent wheel  39  has two regions, one of which is provided with a diffuser for transmission and the other of which is provided with a phosphor layer. The region of the fluorescent wheel  39  with the phosphor layer is formed by applying phosphor to a surface onto which laser light from the laser light source unit  30  is emitted. The phosphor emits green fluorescence when irradiated with blue light. A reflector is formed on the rear face of the phosphor layer. The diffuser of the fluorescent wheel  39  transmits and diffuses blue light. The fluorescent wheel  39  is driven and rotated by a motor  40  that is a rotary drive. The rotation is controlled together with the micromirror device  14  to synchronize with each other by the projection processor  13 . During the control, the projection processor  13  detects rotation of a marker (not illustrated) formed on the fluorescent wheel  39  and uses the detection result. 
         [0050]    Blue laser light incident on the phosphor layer of the fluorescent wheel  39  is emitted as green fluorescence. The green fluorescence is emitted isotropically. Fluorescence emitted toward the rear face of the phosphor layer is reflected by the reflector. The fluorescence emitted by the phosphor layer is thus guided toward the lenses  38  and  37 . Green light transmitted by the lenses  38  and  37  is incident on the first dichroic mirror  36 . 
         [0051]    On the optical path of the green light reflected by the first dichroic mirror  36 , a lens  41  and a second dichroic mirror  42  are arranged. The green light reflected by the first dichroic mirror  36  is incident on the second dichroic mirror  42  via the lens  41 . The second dichroic mirror  42  transmits blue light and reflects red light and green light. On the optical path of green light reflected by the second dichroic mirror  42 , a lens  43 , a mirror  44 , the light intensity distribution uniformizing element  100  according to the first embodiment, and the mirror  16  are arranged in this order. As described above, the light intensity distribution uniformizing element  100  is an element that includes the microlens array  110  and the coupling lens  160  and makes the intensity distribution of light beams uniform. The green light reflected by the second dichroic mirror  42  is incident on the light intensity distribution uniformizing element  100  via the lens  43  and the mirror  44 . The green light is converted into a beam with uniform intensity distribution by the light intensity distribution uniformizing element  100  and incident on the mirror  16 . 
         [0052]    Meanwhile, the blue laser light emitted by the laser light source unit  30  passes the following path if the diffuser of the fluorescent wheel  39  is present on the optical path of the blue laser light. The blue laser light emitted by the laser light source unit  30  is incident on the diffuser of the fluorescent wheel  39  and is diffused and transmitted by the diffuser. On the optical path of the transmitted light, a lens  50 , a mirror  51 , a lens  52 , a mirror  53 , a lens  54 , and the second dichroic mirror  42 . The blue light transmitted by the diffuser is reflected by the mirror  51  via the lens  50 , further reflected by the mirror  53  via the lens  52 , and incident on the second dichroic mirror  42  via the lens  54 . The blue light reflected by the second dichroic mirror  42  is incident on the light intensity distribution uniformizing element  100  via the lens  43  and the mirror  44 . The blue light is converted into a beam with uniform intensity distribution by the light intensity distribution uniformizing element  100  and incident on the mirror  16 . 
         [0053]    The light source unit  15  has a light emitting diode (LED)  55  that is a semiconductor light emitting device configured to emit red light as a light source. On the optical path of the light emitted by the LED  55 , lenses  56  and  57  and the first dichroic mirror  36  are arranged. The red light emitted by the LED  55  is incident on the first dichroic mirror  36  via the lenses  56  and  57 . The red light transmitted by the first dichroic mirror  36  is incident on the second dichroic mirror  42  via the lens  41 . The red light reflected by the second dichroic mirror  42  is incident on the light intensity distribution uniformizing element  100  via the lens  43  and the mirror  44 . The red light is converted into a beam with uniform intensity distribution by the light intensity distribution uniformizing element  100  and incident on the mirror  16 . 
         [0054]    The green light, blue light, and red light reflected by the mirror  16  are emitted onto the micromirror device  14  via the lens  45 . The micromirror device  14  forms an optical image by the light reflected toward the projector lens unit  17 . The optical image is projected onto the screen (not illustrated) or the like via the lens  45  and the projector lens unit  17 . 
         [0055]    Operation of the projector  10  according to the present embodiment will be described. The following operation is executed by the projection processor  13  under the control of the CPU  18 . The timing of emission by the LDs  31  for emitting blue light and the LED  55  for emitting red light of the laser light source unit  30 , the timing of rotation of the fluorescent wheel  39  in synchronization with the emission timing, and the operation of the micromirror device  14  are all controlled by the projection processor  13 . 
         [0056]    An example in which three color rays of red (R), green (G), and blue (B) are incident on the micromirror device  14  will be described. At the timing at which red light is to be incident on the micromirror device  14 , the LED  55  for emitting red light is turned on and the LDs  31  for emitting blue light are turned off. At the timing at which green light is to be incident on the micromirror device  14 , the LED  55  for emitting red light is turned off and the LDs  31  for emitting blue light are turned on. At this point, the fluorescent wheel  39  is positioned by the rotation by the motor  40  so that the phosphor layer is on the optical path of blue light. At the timing at which blue light is to be incident on the micromirror device  14 , the LED  55  for emitting red light is turned off and the LDs  31  for emitting blue light are turned on. At this point, the fluorescent wheel  39  is positioned by the rotation by the motor  40  so that the diffuser is on the optical path of blue light. As described above, the red light, green light, and blue light are sequentially made to be incident on the micromirror device  14  by controlling turning on/off of the LED  55  and the LDs  31  on/off and the angle of rotation of the fluorescent wheel  39  by the motor  40 . 
         [0057]    The micromirror device  14  guides incident light of each color for each micromirror (for each pixel) to the projector lens unit  17  for a longer time as the gradation based on image data is higher and for a shorter time as the gradation is lower. In other words, the projection processor  13  controls the micromirror device  14  so that a micromirror corresponding to a pixel with high gradation to be ON for a long time and that a micromirror corresponding to a pixel with low gradation to be OFF for a long time. In this manner, the gradation of each color of light emitted by the projector lens unit  17  can be expressed by each micromirror (pixel). 
         [0058]    The gradations expressed by the times during which micromirrors are ON of the respective colors are combined for each frame to express an image. As described above, projection light expressing an image is emitted from the projector lens unit  17 . The image is displayed on the screen or the like by projecting the projection light onto the screen. 
         [0059]    Although an example of a projector using three colors of red light, green light, and blue light is presented in the above description, a projector may be configured to emit light of complementary colors such as magenta and yellow or white light and combine rays of these colors to form an image. 
         [0060]    In the present embodiment, the microlens array  110  is provided so that light beams are perpendicularly incident thereon. Furthermore, the reflective surface of the micromirror device  14  and the irradiation surface  170  described with reference to  FIG. 1  are coincident. With such a light intensity distribution uniformizing element  100 , uniform light is emitted to the micromirror device. As a result, non-uniformity in the gradation in a projected image caused by the light source is resolved. 
         [0061]    Although a case in which the light intensity distribution uniformizing element  100  is used in a projector is presented in the present embodiment, the application of the light intensity distribution uniformizing element  100  is not limited thereto. The light intensity distribution uniformizing element  100  according to the present embodiment can be used in various scenes where uniform light intensity distribution is required. 
         [0062]    Furthermore, the invention is not limited to the embodiments described above but can be modified in various manners without departing from the scope of the invention in carrying out the invention. Moreover, the functions executed in the embodiments described above can be combined as much as possible as appropriate. The embodiments described above include various steps, from which various inventions can be extracted depending on the appropriate combinations of disclosed features. For example, if the effect can be produced without some of the features presented in the embodiments, a configuration without the features can be extracted as an invention.