Abstract:
A spectroscopy device that separates input light into a plurality of wavelength ranges. A metal body has a hole or aperture which is open on the upper side. The hole or aperture is formed in a polygonal shape having at least a pair of opposite faces not parallel to each other in horizontal cross-section. Inner side faces of the hole or aperture are finished as mirror like reflection surfaces. Polarized input light inputted from the opening to the hole or aperture is reflected by the reflection surfaces and a standing wave is generated inside of the hole or aperture by self interference, whereby the input light is separated into a plurality of wavelength ranges.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a spectroscopy device for spectrally separating inputted light, and a spectroscopy apparatus and method using the same. 
         [0003]    2. Description of the Related Art 
         [0004]    As for spectroscopy devices, spectroscopy apparatuses, and spectroscopy methods, various structures are known. But, in general, they spectrally separate input light using a prism, and record the separated light beams after converting to electrical signals using an image sensor. Conventional spectrophotometers structured in the manner as described above have difficulty to detect a plurality of wavelengths at the same time, because a change in the wavelength to be separated corresponds to a mechanical change in the drive mechanism of the prism. Consequently, the following inventions have been made to solve this problem. 
         [0005]    Japanese Unexamined Patent Publication No. 8 (1996)-193884 discloses a spectroscopy apparatus having the following disposed serially on the optical path in the order of: a first imaging lens, a slit plate, a first collimator lens, a spectroscopy means, a second collimator lens, a microprism array, a second imaging lens, and a two-dimensional array sensor. A light beam having a predetermined wavelength of those separated by the spectroscopy means is deflected by the microprism array and outputted in a predetermined direction. This causes a spectroscopic image to be formed on a predetermined sensor of the two-dimensional array sensor, whereby a spectroscopy apparatus capable of obtaining multitudes of spectra at the same time is realized. 
         [0006]    U.S. Pat. No. 5,729,011 discloses a spectroscopy apparatus in which a field mask and a plurality of light refraction surfaces having normal lines in directions different from the directions of the optical axis of the optical system are formed, and a prism is disposed adjacent to the pupil surface of a lens such that the pupil surface of the lens is divided by each refraction surface, in addition to a lens and an image sensor. This causes a plurality of the same images generated on the image sensor to be formed as a plurality of the same spectroscopic images having a different wavelength component from each other, whereby a spectroscopy apparatus capable of obtaining spectroscopic images corresponding to a plurality of wavelengths at the same time is realized. 
         [0007]    These spectroscopy apparatuses require an optical system including a prism and a lens for the image sensor imaging a spectroscopic image, so that a large space is required in terms of component arrangement or optical design. Consequently, the size of these spectroscopy apparatuses becomes very large. Further, components including the prism, lens, and image sensor are aligned over the housings, so that a prolonged time is required for the adjustment and the alignment accuracy is also limited. 
         [0008]    It is an object of the present invention, therefore, to provide a novel spectroscopy device which is free from those problems found in the conventional spectroscopy devices, spectroscopy apparatuses, and spectroscopy methods. 
       SUMMARY OF THE INVENTION 
       [0009]    The spectroscopy device according to the present invention is a device including a metal plate having a hole or aperture formed in a polygonal shape having at least a pair of opposite faces not parallel to each other in horizontal cross-section, the hole or aperture being open on the upper side wherein: 
         [0010]    inner side faces of the hole or aperture are finished as mirror like reflection surfaces; and 
         [0011]    a standing wave is generated inside of the hole or aperture by interference caused by reflection of polarized input light inputted from the opening to the hole or aperture on the reflection surfaces, whereby the input light is separated into a plurality of wavelength ranges. 
         [0012]    The terms “hole” and “aperture” as used herein mean a hole having a bottom and a through aperture respectively. 
         [0013]    The hole or aperture has a size which may generate a standing wave inside thereof by reflecting light inputted therein, that is, a size not significantly greater than the wavelength of the light, for example, several times thereof. 
         [0014]    The term “metal plate” generally means a thin metal having an upper face (front face) and a bottom face (rear face) which are parallel to each other, but it is not necessarily limited here to those having accurately parallel upper and bottom faces. Also, it is not limited to those having a thickness which is small in comparison with a size in horizontal directions. 
         [0015]    The term “input light is separated into a plurality of wavelength ranges” as used herein means that light beams having different wavelength ranges are focused or stand on different positions inside of the hole or aperture and, if a sensor having light receiving elements corresponding to these positions is disposed, light beams having different wavelengths may be detected by the respective light receiving elements. As an example, spectral components having different wavelength ranges may be focused at horizontally different positions on the bottom of the hole or aperture. 
         [0016]    The hole or aperture needs to have a polygonal shape in horizontal cross-section with at least a pair of opposite faces not parallel to each other, which is a condition for generating the standing wave described above and focusing different wavelength ranges at different positions. More specifically, for example, the shape may be a trapezoid, such as an isosceles trapezoid. The legs of a trapezoid form a pair of opposite faces not parallel to each other, so that it is thought that polarized light inputted from upper side of the hole or aperture, that is, from the opening described above repeats reflections between the opposite faces, whereby different wavelength ranges are focused at different positions adjacent to the bottom of the hole or aperture. 
         [0017]    More specifically, the spectroscopy device of the present invention may be a device including a metal plate having a uniform thickness with an aperture running from the upper face to the bottom face, wherein: 
         [0018]    when a cross-section of the aperture is taken parallel to the upper and bottom faces of the metal plate and three of the sides forming the cross-section are selected in descending order of length, extended lines of the three sides form an isosceles triangle having a narrow apex angle; 
         [0019]    at least those of the inner side faces of the aperture contacting isosceles sides of the isosceles triangle are finished as mirror like reflection surfaces; and 
         [0020]    polarized input light inputted from the upper face of the metal plate to the aperture is separated into a plurality of wavelength ranges by interference caused by reflection of the input light on the reflection surfaces of the aperture. 
         [0021]    Further, the spectroscopy device of the present invention may further include a polarizing element on the upper side thereof, and the polarization direction of the polarizing element is set to a direction parallel or orthogonal to the perpendicular bisector of the bottom side of the isosceles triangle. 
         [0022]    The spectroscopy apparatus of the present invention may be an apparatus including any of the spectroscopy devices described above, and the aperture runs perpendicular to the upper and bottom faces of the metal plate. 
         [0023]    Further, the spectroscopy apparatus of the present invention may be an apparatus including any of the spectroscopy devices described above and a light receiving element disposed at a position on the bottom face of the spectroscopy device corresponding to a localized position of spectral distribution of the input light, wherein the spectral distribution is converted to an electrical signal by the light receiving element. 
         [0024]    Still further, the spectroscopy apparatus of the present invention may be an apparatus including a plurality of the light receiving elements disposed at positions corresponding to a plurality of localized positions of the spectral distribution. 
         [0025]    Further, the spectroscopy apparatus of the present invention may be a two-dimensional spectroscopy apparatus including a plurality of the spectroscopy apparatuses disposed two-dimensionally, each being a combination of the spectroscopy device and one or more light receiving elements. 
         [0026]    The spectroscopy method of the present invention is a method including the steps of: 
         [0027]    providing a metal plate having a hole or aperture formed in a polygonal shape having at least a pair of opposite faces not parallel to each other in horizontal cross-section, the hole or aperture being open on the upper side with inner side faces thereof finished as mirror like reflection surfaces; and 
         [0028]    inputting polarized input light from the opening to the hole or aperture and generating a standing wave inside of the hole or aperture by interference caused by reflection of the input light on the reflection surfaces, whereby separating the input light into a plurality of wavelength ranges. 
         [0029]    The spectroscopy device of the present includes a metal plate having a hole or aperture formed in a polygonal shape having at least a pair of opposite faces not parallel to each other in horizontal cross-section. The hole or aperture is open on the upper side with inner side faces thereof finished as mirror like reflection surfaces, and a standing wave is generated inside of the hole or aperture by interference caused by reflection of polarized input light inputted from the opening to the hole or aperture on the reflection surfaces, whereby the input light is separated into a plurality of wavelength ranges. Thus, the spectroscopy device of the present invention has a very simple structure, yet it may provide spectroscopic effects identical to those of conventional spectroscopy devices. 
         [0030]    Further, the spectroscopy device and light receiving element may be manufactured by a semiconductor manufacturing process, so that a compact and high accurate spectroscopy apparatus may be realized. 
         [0031]    Still further, an optical system including a prism and a lens is not required for the image sensor imaging a spectroscopic image, so that the space required in terms of component arrangement or optical design may be reduced. Consequently, the size of the spectroscopy apparatus may become very compact. Further, components including prism, lens, and image sensor are not used, so that it is not necessary to align them over housings. Consequently, time required for component adjustment is eliminated and at the same time alignment accuracy may be improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIGS. 1A ,  1 B,  1 C illustrate an example structure of the spectroscopy device of the present invention. 
           [0033]      FIG. 2  is a conceptual diagram of the spectroscopy device of the present invention. 
           [0034]      FIGS. 3A ,  3 B define a shape of the aperture of the spectroscopy device of the present invention. 
           [0035]      FIGS. 4A to 4F  illustrate spectroscopic results of Y direction polarized input light with respect to each wavelength using the spectroscopy device of the present invention. 
           [0036]      FIG. 5  illustrates spectral intensity of Y direction polarized input light using the spectroscopy device of the present invention. 
           [0037]      FIG. 6  illustrates wavelength dependence of peak position of spectral intensity of Y direction polarized input light using the spectroscopy device of the present invention. 
           [0038]      FIGS. 7A to 7F  illustrate spectroscopic results of X direction polarized input light with respect to each wavelength using the spectroscopy device of the present invention. 
           [0039]      FIG. 8  illustrates spectral intensity of X direction polarized input light using the spectroscopy device of the present invention (raw data). 
           [0040]      FIGS. 9A ,  9 B illustrate modified examples of the shape of the aperture of the spectroscopy device of the present invention. 
           [0041]      FIGS. 10A to 10H  illustrate spectroscopic results of Y direction polarized input light using the spectroscopy device having the modified shape of the aperture. 
           [0042]      FIGS. 11A ,  11 B,  11 C illustrate a second embodiment of the spectroscopy device of the present invention. 
           [0043]      FIGS. 12A ,  12 B,  12 C illustrate spectroscopic results of Y direction polarized input light using the second embodiment of the spectroscopy device of the present invention. 
           [0044]      FIG. 13  illustrates an example spectroscopy apparatus constructed using the spectroscopy device of the present invention. 
           [0045]      FIG. 14  illustrates a configuration of image sensor incorporated in the spectroscopy apparatus. 
           [0046]      FIG. 15  illustrates a two-dimensional spectroscopy apparatus formed by disposing a plurality of the spectroscopy apparatus of the present invention two-dimensionally. 
           [0047]      FIG. 16  illustrates a fifth embodiment of the spectroscopy device of the present invention. 
           [0048]      FIGS. 17A to 17E  illustrate spectral intensity of Y direction polarized input light with respect to Z direction using the spectroscopy device of the present invention. 
           [0049]      FIG. 18  illustrates a sixth embodiment of the spectroscopy device of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0050]    Hereinafter, exemplary embodiments of the spectroscopy device, spectroscopy apparatus, and spectroscopy method of the present invention will be described with reference to the accompanying drawings. 
       First Embodiment 
       [0051]      FIGS. 1A ,  1 B,  1 C illustrate an example structure of the spectroscopy device  10  of the present invention.  FIG. 1A  is a top view of the spectroscopy device  10 , illustrating the shape thereof viewed from the light input face. The spectroscopy device  10  is a structure made of a metal plate having a uniform thickness with an aperture  20  vertically running from the upper face, that is, input face to the bottom face, that is, output face.  FIG. 1A  depicts as if one spectroscopy device were independent from other spectroscopy devices, but it is preferable to have a structure in which the metal plate is shared by other adjacent spectroscopy devices from the standpoint of manufacture and use. Accordingly, the outer shape shown in  FIG. 1A  is an imaginary shape.  FIG. 1B  is a cross-sectional view taken along the line A-A′ in  FIG. 1A . The metal plate forming the structure of the spectroscopy device  10  reflects input light on the inner walls of the aperture  20 . In the present embodiment, the reflection surfaces  11 ,  12  intersect perpendicularly with the input face  16  and output face  18 .  FIG. 1C  is a cross-sectional view taken along the line B-B′ in  FIG. 1A . The reflection surfaces  13 ,  14  intersect perpendicularly with the input face  16  and output face  18  as in  FIG. 1B . 
         [0052]    As illustrated in a conceptual diagram of the spectroscopy device of the present invention in  FIG. 2 , the spectral separation is achieved by a standing wave generated when input light from the input face  16  of the spectroscopy apparatus  10  and not shown reflection light of the input light reflected on the reflection surfaces reach the output face and interfere with each other. The standing wave at the output face  18  corresponds to the spectral intensity distribution. 
         [0053]      FIGS. 3A ,  3 B define the shape of the aperture of the spectroscopy device of the present invention. The shape of the aperture  20  of the spectroscopy device of the present invention shown in  FIG. 3A  is defined in the following manner. Namely, the geometry enclosed by extended lines of three sides, side  22 , side  26 , and side  28  of those forming the aperture  20 , that is, the geometry enclosed by the extended line  23 , extended line  27 , and extended line  29  forms an isosceles triangle  30  having a narrow apex angle H shown in  FIG. 3B , that is, forms a triangle. The shape of the aperture  20  shown in  FIG. 3A  is a trapezoid which is formed by cutting an apex section of the isosceles triangle  30  parallel to the bottom side  28  thereof. This is dependent on the wavelength range of spectroscopic result to be obtained. If a short wavelength range of those of spectroscopic result to be obtained is not required, the apex section of the isosceles triangle may be omitted. Contrary, where a spectral separation is to be performed to a shorter wavelength range, the aperture becomes more like an isosceles triangle, and eventually becomes an isosceles triangle. 
         [0054]    In the spectroscopy device of the present invention, input light is reflected by the reflection surfaces of inner walls, and spectral separation is achieved by a standing wave generated by the reflection light and input light. Thus, if an optical energy loss is great when input light is reflected by the reflection surfaces, the energy of the input light is lost when reflected by the inner walls of the structure of the spectroscopy apparatus, and it is difficult to obtain a clear intensity distribution at the output face. Therefore, it is necessary to select a material having a low reflection energy loss for the metal plate. For example, silver is known to be a metal having an excellent reflectance and may be used. In addition, gold, copper, and mirror materials such as gold, copper, an alloy of copper and tin, aluminum, and the like may be used. Technologies for accurately providing the aperture in these materials may include an anisotropic etching of semiconductor manufacturing technology, ultraprecision machining using pulse laser, fiber laser, or the like. Use of the semiconductor manufacturing technology allows high accurate spectroscopy devices to be stably produced. 
         [0055]    Since only the inner walls of the aperture are required to be reflective, the aperture and other structures around thereof may be formed of a semiconductor substrate made of silicon which is the same material as that of a light receiving element, to be described later, or the like, and a thin film or a plate of gold, silver, copper, or an alloy of copper and tin may be used only for the inner walls. The aperture may be provided in the semiconductor substrate also by the semiconductor manufacturing technology. When forming a thin film of gold, silver, copper, or an alloy of copper and tin on the inner walls of the aperture provided in the semiconductor substrate, sputtering, vapor deposition, plating, or the like may be used. Where such structure is employed, an integral structure with light receiving elements which can be made of the same semiconductor substrate may be realized. 
         [0056]      FIGS. 4A to 4F  illustrate spectroscopic results of Y direction polarized input light using the spectroscopy device of the present invention. The coordinate system shown on the left of  FIG. 4A  corresponds to the coordinate system of the spectroscopy device shown in  FIGS. 1A to 1C . It is a coordinate system with the vertical axis representing X direction of the spectroscopy device viewed from the top and the horizontal axis representing Y direction of the spectroscopy device viewed from the top indicating the manners in which input light, which is polarized in Y direction, is spectrally separated at each of six wavelengths from 440 nm ( FIG. 4A ) to 690 nm ( FIG. 4F ). In each of the graphs in  FIGS. 4A to 4F , a more whitish portion represents a peak where the light having the wavelength is present strongly as standing wave. The peak position varies with the wavelength, showing that the spectroscopy device of the present embodiment functions as a spectroscopy device. 
         [0057]      FIG. 5  illustrates spectral intensity of Y direction polarized input light using the spectroscopy device shown in  FIGS. 4A to 4F . In the graph shown in  FIG. 5 , the coordinate of Y direction (distance) is plotted on Y axis and spectral intensity is plotted on X axis on the central axis of X direction of the spectroscopy device. The Y coordinate is normalized by the maximum value of the spectral intensity, so that the graph shows relative values. The graph clearly shows the position where the standing wave presents strongly with respect to each wavelength, which is not clear in  FIGS. 4A to 4F . For example, the 440 nm wavelength has its peaks at three positions on Y axis near 250, 2000, and 4200 nm. Looking at the Y coordinate from around 2500 to 4500 nm, it is known that a peak of the 590 nm wavelength is present near 2700 nm, and peaks of shorter wavelengths are present as the value of Y coordinate is increased. 
         [0058]    Note that clear peaks of two wavelengths of 640 and 690 nm are not observed in the graph. As clear from  FIGS. 4E and 4F , this is because the two wavelengths have their peaks at positions away from the central axis of X direction of the spectroscopy device. 
         [0059]      FIG. 6  illustrates wavelength dependence of peak position of spectral intensity of Y direction polarized input light using the spectroscopy device of the present invention. X axis of the graph represents wavelength of input light and Y axis represents peak position of spectral intensity. The peak position  0  of the spectral intensity corresponds to the bottom side  28  of the spectroscopy device shown in  FIG. 3A . 
         [0060]    Peaks of spectral intensity of each wavelength may be largely classified into two groups. In a first group closer to 0 in the Y axis direction, the peak positions of the intensity move closer to 0 almost linearly as the wavelength becomes longer within the wavelength range from 440 to 540 nm. Contrary, the peak positions of the intensity move away from 0 almost linearly as the wavelength becomes longer within the wavelength range from 590 to 690 nm. In another group, that is, in a second group, the peak positions of the intensity move closer to 0 almost linearly as the wavelength becomes longer within the wavelength range from 440 to 640 nm. Contrary, the peak positions of the intensity move away from 0 almost linearly as the wavelength becomes longer within the wavelength range from 640 to 690 nm. 
         [0061]    The reason that all the peak positions of intensity do not move closer to 0 almost linearly as the wavelength becomes longer is that input light is resonated in the aperture having a finite size. The reflection surface of the bottom side  28  has an effect on the resonance. If the bottom side  28  is located at an infinite distance, the peak positions of intensity move closer to 0 almost linearly as the wavelength becomes longer. 
       First Modification of First Embodiment 
       [0062]      FIGS. 7A to 7F  illustrate spectroscopic results of X direction polarized input light using the spectroscopy device of the present invention. The coordinate system shown on the left of  FIG. 7A  corresponds to the coordinate system of the spectroscopy device shown in  FIG. 1A .  FIGS. 7A to 7F  illustrate the manners in which input light is spectrally separated at each of six wavelengths from 440 nm ( FIG. 7A ) to 690 nm ( FIG. 7F ). In each of the graphs in  FIG. 7A to 7F , a more whitish portion represents a peak where the light having the wavelength is present strongly as standing wave. The peak position varies with the wavelength, showing that the spectroscopy device of the present embodiment functions as a spectroscopy device. Unlike the results of Y direction polarized light shown in  FIGS. 4A to 4F , line like peaks parallel to X axis are observed. 
         [0063]      FIG. 8  illustrates spectral intensity of X direction polarized input light using the spectroscopy device shown in  FIGS. 4A to 4F . In the graph shown in  FIG. 8 , the coordinate of Y direction (distance) is plotted on Y axis and spectral intensity is plotted on X axis on the central axis of X direction of the spectroscopy device. The Y coordinate is normalized by the maximum value of the spectral intensity, so that the graph shows relative values. Positions where the standing wave is present strongly with respect to each wavelength which can be identified separately are in the vicinity of 2800 and 3800 nm of Y coordinate of 440 nm wavelength. If considering as a wavelength range, for example, from 490 to 590 nm, then a peak is thought to present in the vicinity of 3400 nm of Y coordinate, so that spectral separation may be achieved by the present spectroscopy device using these characteristics. 
       Second Modification of First Embodiment 
       [0064]      FIGS. 9A ,  9 B illustrate modified examples of the shape of the aperture of the spectroscopy device of the present invention.  FIGS. 9A ,  9 B are basically identical, so that  FIG. 9B  will primarily be described here. The aperture  92  of spectroscopy device of the present embodiment is defined in the following manner. Namely, the geometry enclosed by extended lines of three sides, side  22 , side  26 , and side  28  of those forming the aperture  92 , that is, the geometry enclosed by the extended line  23 , extended line  27 , and extended line  29  forms an isosceles triangle  30  with a narrow apex angle H, that is, forms a triangle. The shape of the aperture  92  shown in  FIG. 9B  is a trapezoid which is formed by cutting an apex section of the isosceles triangle  30  parallel to the bottom side  28  thereof. The aperture  92  differs from that of the first embodiment in that it has rounded corners. 
         [0065]    In  FIG. 9A , the corners are rounded with Ra=0.1 μm, and in  FIG. 9B , the corners are rounded with Rb=0.5 μm. The shape of the aperture shown in  FIG. 1  is an ideal shape, and if shaped like this, highest performance may be provided. Where practical machining accuracy is taken into account, however, a shape having rounded corners may be produced more inexpensively. 
         [0066]      FIGS. 10A to 10H  illustrate spectroscopic results of Y direction polarized input light using the spectroscopy device according to the present embodiment. Although not shown, the coordinate system of  FIGS. 10A to 10H  is identical to the coordinate system of the spectroscopy apparatus shown in  FIG. 9A .  FIGS. 10A to 10H  illustrate the manners in which input light is spectrally separated at each of four wavelengths spaced apart by 100 nm from 380 nm ( FIGS. 10A and 10E ) to 680 nm ( FIGS. 10D and 10H ). In each of the graphs  10 A to  10 H, a more whitish portion represents a peak where the light having the wavelength is present strongly as standing wave. The peak positions where the standing wave is present strongly and the distribution thereof are substantially identical between  FIGS. 10A to 10D , which are spectroscopic results of the aperture rounded with the radius of 0.1 μm and  FIGS. 10E to 10H , which are spectroscopic results of the aperture rounded with the radius of 0.5 μm, although details are different. This indicates that either of them functions as a spectroscopy device. 
       Second Embodiment 
       [0067]      FIGS. 11A ,  1113 ,  11 C illustrate a second embodiment of the spectroscopy device  10  of the present invention.  FIG. 11A  is a top view thereof. The spectroscopy device  10  is a structure made of a metal plate having a uniform thickness with a tapered aperture  21  running from the upper face, that is, the input face to the bottom face, that is, output face. It differs from the spectroscopy device  10  according to the first embodiment shown in  FIG. 1  in that the aperture  21  has a shape such that an input face shape  1101  of input light to the spectroscopy device  10  and an output face shape  1102  become analogous. Consequently, reflection surfaces connecting the input face shape  1101  and output face shape  1102  intersect therewith at an angle other than right angle. 
         [0068]      FIG. 11B  is a cross-sectional view taken along the line B-B′ in  FIG. 11A . The metal plate forming the structure of the spectroscopy device  10  reflects input light at inner walls of the aperture  21 . In the present embodiment, the reflection surfaces  1103  intersect with the input face  1104  and output face  1105  at an angle other than right angle.  FIG. 11C  is a cross-sectional view taken along the line C-C′ in  FIG. 11A . The reflection surfaces  1103  intersect with the input face  1104  and output face  1105  at an angle other than right angle as in  FIG. 11B . 
         [0069]      FIGS. 12A to 12C  illustrate spectroscopic results of Y direction polarized input light using the second embodiment of the spectroscopy device  10  of the present invention. The coordinate system shown on the left of  FIG. 12A  corresponds to the coordinate system of the spectroscopy device shown in  FIGS. 11A to 11C . But, note that the positive direction of X axis is reversed (Here, Figures may be reversed upside down to align the directions).  FIG. 11A  illustrates spectroscopic results of 440 nm wavelength,  FIG. 11B  illustrates spectroscopic results of 540 nm wavelength, and  FIG. 11C  illustrates spectroscopic results of 640 nm wavelength. The light is visually observed in blue in  FIG. 12A , green in  FIG. 12B , and red in  FIG. 12C . A comparison between  FIGS. 12A and 12B  shows that the peak position is moved from 106 nm to 110 nm in Y direction, although the difference is small. Further, a comparison between  FIGS. 12B and 12C  shows that the peak position is further moved to 112 nm, and also second and third peaks appear in the vicinity of 145 nm and 170 nm respectively. The results show that the spectroscopy device of the present embodiment functions as a spectroscopy device. 
       Third Embodiment 
       [0070]      FIG. 13  illustrates an example spectroscopy apparatus  1300  constructed using a spectroscopy device  10  of the present invention. The spectroscopy device  10  may be either one of the spectroscopy devices described above. Input light to the spectroscopy device (white light, as an example) is spectrally separated by the aperture  20  and light receiving elements ( 1302  to  1312 ) are disposed at localized positions of the spectral distribution on the bottom face, thereby a spectroscopy apparatus capable of converting the spectral distribution to electrical signals is realized. 
         [0071]    The light receiving elements ( 1302  to  1312 ) are formed on a semiconductor (e.g., silicon) substrate  1301 . The light receiving elements may be those formed on a general semiconductor substrate using a common manufacturing method. 
         [0072]    Since the wavelength received by each light receiving element is constant, if the individual light receiving elements ( 1302  to  1312 ) are capable of changing receiving sensitivity according to the wavelength, an efficient spectroscopy apparatus may be constructed by adjusting the receiving sensitivity of the individual light receiving elements to the respective receiving wavelengths. For example, the light receiving element  1302  receives a blue wavelength, thus the use of a light receiving element having spectroscopic characteristics with increased sensitivity for blue wavelength allows the spectroscopy apparatus  1300  to be an apparatus capable of reliably obtaining spectroscopic results even when the input light is weak. 
         [0073]    Where individual light receiving elements ( 1302  to  1312 ) are structured to have the same spectroscopic characteristics, they may be produced by the same manufacturing process as that of conventional image sensors, which allows mass production of the light receiving elements, allowing the spectroscopy apparatus to be realized at low cost. 
         [0074]      FIG. 14  illustrates a configuration of image sensor incorporated in the present spectroscopy apparatus. The image sensor shown in  FIG. 14  is a CMOS image sensor, but a CCD image sensor, or other types of image sensors may be used other than the CMOS image sensor. 
         [0075]    Each light receiving element  1410  includes: a photodiode  1402  for converting light to charges; a reset transistor  1404  for resetting charges stored in the photodiode  1402  according to a signal from a reset line  1405  prior to the start of exposure; an amplifier  1406  for amplifying signals from the photodiode  1402 ; and a readout transistor  1408  for reading out the amplified signals to a readout line  1421  according to a signal from a readout selection signal line  1409 . The readout selection signal line of each row is connected to a vertical shift register  1460  and allows one row of signals to be outputted at the same time in the present embodiment. Each of the readout selection lines is selected by the vertical shift register  1460  as required. 
         [0076]    Signals of received light received by individual light receiving elements are read out through readout lines  1421  to  1431 . Horizontal selection transistors  1441  to  1451  are connected to each of the readout lines, and turned on to establish connection according to a signal from a horizontal shift register  1470 , thereby the signal is outputted to an output line  1480  and eventually outputted from an output terminal  1482 . It is appreciated that the configuration of the present invention is not limited to this, and configuration of these elements may be selected freely. 
         [0077]    The light receiving elements  1302  to  1314  shown in  FIG. 13  correspond to light receiving elements  1420  to  1430  or light receiving elements  1440  to  1450 . The spectroscopy apparatus may be constructed by arranging light receiving elements according to required spectroscopic resolution. Where light receiving elements are disposed at a constant spacing, spectroscopic results of substantially equally spaced wavelengths, as clear from the spectral intensity of Y direction polarized input light using the spectroscopy device of the present invention. This is advantageous because existing image sensors and various types of photo-sensor arrays may be used. 
         [0078]    The spectroscopy device and the light receiving elements are connected to each other by the following steps. First, light receiving elements are formed on a silicon substrate or the like by a semiconductor manufacturing process, and silica glass or the like is stacked to smooth the surface, if not smooth. Thereafter, a metal film is stacked on the smoothed surface of the light receiving elements by plasma CVD or vapor deposition, and finally an aperture is formed by etching or the like. Alternatively, silica glass is further stacked, then an aperture is formed, and a metal film is formed on the reflection surfaces of the aperture by vapor deposition, CVD, or electroless deposition. These steps may be implemented in a semiconductor manufacturing process, which provides advantageous effects that the spectroscopy device may be positioned accurately with respect to the light receiving elements. 
       Fourth Embodiment 
       [0079]      FIG. 15  illustrates a two-dimensional spectroscopy apparatus formed by disposing a plurality of the spectroscopy apparatus of the present invention two-dimensionally. That is, spectroscopy devices  1510  are serially disposed in XY directions to form a two-dimensional spectroscopy apparatus  1500 . This allows spectral separation of a plurality of light sources or measurement of light source spectral distributions to be performed. As described above, the use of the semiconductor manufacturing process allows a plurality of spectroscopy devices to be produced highly accurately on the same spectroscopy apparatus, so that a high accurate two-dimensional spectral measurement apparatus may be realized. Signal outputs may be readout in the same manner as that of an ordinary image sensor, and the outputs may be integrated or separately outputted from each spectroscopy apparatus as required. Further, the two-dimensional spectroscopy apparatus may be used as an ordinary image sensor since spectroscopic results are obtained two-dimensionally. When used as an image sensor, a high sensitivity image sensor may be realized since spectral separation is achieved by standing wave and loss of input light is small. 
       Fifth Embodiment 
       [0080]      FIG. 16  illustrates another embodiment of the spectroscopy device  10  of the present invention.  FIG. 16  is a top view of the aperture thereof. That is, the spectroscopy device  10  is a structure made of a metal plate having a uniform thickness with a trapezoidal aperture  20  vertically running from the upper face, that is, input face to the bottom face, that is, output face. The shape of the aperture  20  has a thickness of 6.27 μm in the depth direction (not shown).  FIGS. 17A to 17E  illustrate spectroscopic results of Y direction polarized input light using the spectroscopy device of the present embodiment. Note that the coordinate system in  FIGS. 17A to 17E  is rotated in comparison with the coordinate system in  FIG. 16  for ease of arrangement of  FIGS. 17A to 17E . FIGS.  17 A to  17 E illustrate the manners in which input light at each of five wavelengths spaced apart by 100 nm at 390 nm ( FIG. 17A ), 490 nm ( FIG. 17B ), 590 nm ( FIG. 17C ), 690 nm ( FIG. 17D ), and 790 nm is spectrally separated at eight cross-sections in the depth direction Z, from Z=0 to Z=6.3 μm. In each of the graphs  17 A to  17 E, a more whitish portion represents a peak where the light having the wavelength is present strongly as standing wave. 
         [0081]    As clear from  FIGS. 17A to 17E , the peak position where the standing waves present strongly and the distribution thereof appears at a position closer to the center as the depth in the Z direction is increased. At Z=0 μm, a standing wave parallel to the sides of Y direction (oblique sides of the trapezoid) of the aperture  20  appears, but a position where it appears strongly is not present. Comparison of  FIGS. 17A to 17E  shows that the standing wave has a tendency to reduce the wave number (stripes in Figures) as the wavelength becomes long. At the wavelength of 790 nm shown in  FIG. 17E , a strong peak appears in the center at a depth greater than or equal to Z=2.7 μm. Strong peaks appear in the center for the wavelength of 690 nm shown in  FIG. 17D  at a depth greater than or equal to Z=3.6 μm, for the wavelength of 590 nm and 490 nm shown in  FIGS. 17C and 17B , at a depth greater than or equal to Z=4.5 μm, and for the wavelength of 390 nm shown in  FIG. 17A , at a depth greater than or equal to Z=5.4 μm. This shows that a depth greater than or equal to Z=5.4 μm is adequate when spectral separation is desired to be obtained at the center for all of the wavelengths shown in  FIGS. 17A to 17E . 
       Sixth Embodiment 
       [0082]      FIG. 18  illustrates variations of the shape of the aperture of the spectroscopy device of the present invention in a tabular form. In the  FIG. 18 , the aperture shapes are largely divided into left and right groups having Y direction lengths of 12.8 μm and 6.4 μm respectively. Each group is further divided into three groups having X direction lengths of left sides of 6.4, 4.8, and 3.2 μm respectively. With respect to each of the six different shapes, the ratio of the right side to the left side is changed from 0% (i.e., isosceles triangle) to 75% with an increment of 25% to produce the aperture samples. It has been demonstrated that these aperture shapes function as spectroscopy devices.