Dichroic mirror array

Abstract

To provide multi-color detection of an incident light that is highly sensitive, highly accurate and independent.SOLUTION: A dichroic mirror array includes: a first group arranging m(m≥2) dichroic mirrors along a positive direction of an X axis in order in parallel to each other; and a second group arranging n(n≥2) dichroic mirrors along a negative direction of the X axis in order in parallel to each other. m+n≥6 is satisfied, and X coordinates at DA2 to DAm are positive; X coordinates at DB2 to DBn are negative. DA1 to DAm incidence planes and DB1 to DBn incidence planes are vertical to an XZ plane. An inclination on a straight line XZ flat surface projecting a normal line of the DA1 to DAm incidence planes onto the XZ flat surface is negative; an inclination on the straight line XZ flat surface of a straight line projecting a normal line of the DB1 to DBn incidence planes onto the XZ plane is positive. Z coordinates at DA1 are smaller than Z coordinates at DB1. The dichroic mirror array divides at least one incident light into at least m+n-1 irradiation lights.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to dichroic mirror arrays. [Background technology]

[0002] A dichroic mirror array is a set of dichroic mirrors with different spectral characteristics (wavelength dependence of transmitted and reflected light relative to incident light) arranged parallel to one another in the same direction at approximately equal intervals. Dichroic mirror arrays are installed in photodetection devices that detect and analyze light emitted from a sample, such as capillary array DNA sequencers and automatic biochemical analyzers.

[0003] A light beam incident on the dichroic mirror array is split into multiple light beams (split light beams) with different wavelength bands by repeatedly reflecting and transmitting through each dichroic mirror in the order of its arrangement. The split light beams by the dichroic mirror array are detected (multicolor detection) by, for example, a CCD sensor. Alternatively, multiple light beams with different wavelength bands incident on each dichroic mirror are combined into a single light beam with different wavelength bands superimposed on each other by repeatedly reflecting and transmitting through each dichroic mirror.

[0004] Patent Document 1 discloses a photodetector using a dichroic mirror array, which describes a "spectroscopic device that splits incident light into light of different wavelength bands and detects the light of each wavelength band, comprising: a spectroscopic section in which a plurality of spectroscopic elements having different wavelength band characteristics are arranged; a wavelength selecting section having a plurality of wavelength selecting elements arranged opposite each of the spectroscopic elements; a photodetector including a photomultiplier tube having a photoelectric surface that photoelectrically converts transmitted light from the plurality of wavelength selecting elements, a plurality of electron multiplication paths arranged corresponding to each of the plurality of wavelength selecting elements, and a plurality of anodes arranged corresponding to each of the electron multiplication paths; and a holder that holds the wavelength selecting section within a housing, wherein the holder includes a main body in which the wavelength selecting elements are arranged in one direction and a pair of wall portions protruding from the main body portion so as to face each other, and the spectroscopic elements are arranged between the pair of wall portions along the arrangement direction of the wavelength selecting elements" (see claim 1).

[0005] Generally, if the spacing between multiple light-emitting points is fixed, the shorter the focal length of the focusing lens, the higher the detection sensitivity. On the other hand, the shorter the maximum optical path length, the higher the independent detection (low crosstalk detection). This is because as the maximum optical path length increases, the maximum size of the spot of the split light projected onto the sensor increases, and the spots from adjacent light-emitting points intersect with each other, causing crosstalk. In other words, by miniaturizing the photodetector including the dichroic mirror array, highly sensitive and independent multicolor detection of multiple incident light beams becomes possible.

[0006] Patent Document 2 discloses an optical detection device that is compact, highly sensitive, and has low crosstalk, and it includes: "a light emission detection device having: an array of focusing lenses in which M focusing lenses are arranged, each focusing light emitted from an array of M light emitting points, M≧2, into a light beam; and at least one sensor to which the M light beams are incident in parallel without being refocused, wherein d is the average effective diameter of the M light emitting points, f is the average focal length of the M focusing lenses, p is the average spacing between the M focusing lenses, and g is the average maximum optical path length between the M focusing lenses and the sensor, and d, f, p, and g satisfy a predetermined relationship that enables the M light emissions to be detected with low crosstalk or high sensitivity" (see claim 1).

[0007] On the other hand, as the dichroic mirror array is made smaller, the influence of the thickness of each dichroic mirror becomes non-negligible, and the aperture width, which is the upper limit width of the incident light beam that can be split into multiple split beams by the dichroic mirror array, decreases.

[0008] Patent Document 3 describes a dichroic mirror array in which a plurality of dichroic mirrors numbered 1, 2, . . . , N, where N≧2, are arranged in a first direction in numerical order, and a normal vector of the front surface of each of the plurality of dichroic mirrors is composed of a sum of a positive component in the first direction and a negative component in a second direction perpendicular to the first direction, and the plurality of normal vectors are approximately parallel to each other, and an average of the angles between the plurality of normal vectors and the direction opposite to the second direction is θ0, where 0≦θ0≦90°, and an angle of the substrate of each of the dichroic mirrors is θ1, where θ0 is the average of the angles between the plurality of normal vectors and the direction opposite to the second direction, and The document discloses a "dichroic mirror array" in which θ0, n0, α, β, x, and yz satisfy a predetermined relationship so that the aperture width of the dichroic mirror array can be increased or the optical path length can be reduced, where n0 is the average refractive index, α is the average width of the dichroic mirror substrate, β is the average thickness of the dichroic mirror substrate, x is the average spacing between the dichroic mirrors, and 2≦n≦N. The document also discloses a "dichroic mirror array" in which θ0, n0, α, β, x, and yz satisfy a predetermined relationship so that the aperture width of the dichroic mirror array can be increased or the optical path length can be reduced (see claim 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-242117 [Patent Document 2] International Publication No. 2017 / 145230 [Patent Document 3] International Publication No. 2017 / 145231 Summary of the Invention [Problem to be solved by the invention]

[0010] Generally, to accurately detect and measure each of the light components of the color number CN1 to be analyzed, the color number CN2 detectable by the photodetector must be CN2 ≥ CN1. Furthermore, when detecting light components of the color number CN1, the greater the CN2-CN1 ratio, the higher the detection accuracy of the photodetector. Therefore, to maintain and improve analytical accuracy, it is necessary to increase the color number CN2 detectable by the photodetector.

[0011] As described above, in a photodetector using a dichroic mirror array, reducing the maximum optical path length and downsizing the photodetector enables independent and highly accurate multicolor detection of incident light. However, increasing the number of dichroic mirrors to increase the number of splits of incident light increases the maximum optical path length, making it difficult to achieve independent and highly accurate multicolor detection of incident light.

[0012] Patent Document 2 uses a dichroic mirror array consisting of four types of dichroic mirrors to achieve four-color detection of four incident light beams. In contrast, if eight-color detection of four incident light beams is performed under the same conditions except for using eight types of dichroic mirrors, the maximum size of the split light beam spot projected onto the sensor will be nearly twice as large as in the case of four-color detection. Furthermore, spots originating from different incident light beams will intermingle with each other, resulting in crosstalk. Furthermore, spots originating from different split light beams of a single incident light beam will intermingle with each other, making it impossible to perform high-precision eight-color detection of each incident light beam.

[0013] Furthermore, increasing the number of dichroic mirrors that make up the dichroic mirror array and thus the number of splits of the incident light increases the difference between the minimum optical distance (minimum optical path length) and the maximum optical path length between the condenser lens and the sensor. This increases the difference in spot size between the minimum optical path length and the maximum optical path length, which increases the difference in intensity density between spots with the same total intensity, resulting in a decrease in the overall sensitivity and dynamic range of the photodetector.

[0014] In view of the above circumstances, the present disclosure proposes a photodetection device including a dichroic mirror array that is capable of highly sensitive, highly accurate, and independent multicolor detection of incident light. [Means for solving the problem]

[0015] In order to solve the above problems, the present disclosure provides a dichroic mirror array comprising: a first group in which m (m≧2) dichroic mirrors DA1 to DAm are arranged in order parallel to one another along the positive direction of the X axis, and a second group in which n (n≧2) dichroic mirrors DB1 to DBn are arranged in order parallel to one another along the negative direction of the X axis, in a right-handed XYZ Cartesian coordinate system, wherein m+n≧6, the X coordinates of DA2 to DAm are positive and the X coordinates of DB2 to DBn are negative, and the incident planes of DA1 to DAm and DB1 to DBn are in the XZ plane. The present invention proposes a photodetection device comprising a dichroic mirror array, wherein the dichroic mirror array is perpendicular to the Z axis, the slope of the line formed by projecting the normal to the incident planes of DA1 to DAm onto the XZ plane is negative, and the slope of the line formed by projecting the normal to the incident planes of DB1 to DBn onto the XZ plane is positive, and the dichroic mirror array divides at least one incident light into at least m+n-1 outgoing light beams, and the photodetection device is characterized in that the m+n-1 outgoing light beams can be detected by a sensor provided on the positive side of the dichroic mirror array along the Z axis.

[0016] Further features related to the present disclosure will become apparent from the description and accompanying drawings of this specification, and aspects of the present disclosure may be realized and realized by the elements and combinations of various elements and aspects set forth in the following detailed description and the appended claims. It should be understood that the descriptions in this specification are exemplary and illustrative only and are not intended to limit the scope or application of the present disclosure in any way. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a dichroic mirror array that is capable of highly sensitive, highly accurate, and independent multicolor detection of incident light, and an analytical device using the same. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a dichroic mirror array according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the optical path length required for reflection or transmission by each dichroic mirror. [Figure 3] FIG. 10 is a diagram showing the results of a comparison of the optical path length for dichroic mirror arrays with 3 to 13 divisions. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration and optical path length of a seven-division dichroic mirror array according to Comparative Example 1. [Figure 5] FIG. 2 is a cross-sectional view showing the configuration and optical path length of the seven-division dichroic mirror array according to the first embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a multi-color detection device according to a second embodiment. [Figure 7] FIG. 10 is a schematic diagram showing the configuration of a multi-color detection device according to a third embodiment. [Figure 8] FIG. 10 is a schematic diagram showing the configuration of a capillary array DNA sequencer according to Example 4. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of a nine-division dichroic mirror array according to a fifth embodiment. [Figure 10] This is a model diagram for determining the relationship between the light-emitting point size, focusing lens focal length, light-emitting point distance, sensor distance, and spot size using a ray tracing simulation. [Figure 11] 11 is a graph showing the calculation results of the model of FIG. 10. [Figure 12] 10 is a graph showing the relationship between spatial coordinates, with the center of the spot being set to zero, and relative signal intensity at each sensor distance of the nine-color detection device. [Figure 13] 10 is a graph showing the relationship between the spatial coordinates of the spot and the normalized signal intensity. [Figure 14] 10 is a transmission spectrum of a bandpass filter BP according to a fifth embodiment. [Figure 15]10 shows a transmission spectrum of a dichroic mirror M1 according to Example 5. [Figure 16] 10 shows a transmission spectrum of a dichroic mirror M2 according to Example 5. [Figure 17] 10 shows a transmission spectrum of a dichroic mirror M3 according to Example 5. [Figure 18] 10 is a transmission spectrum of a dichroic mirror M4 according to Example 5. [Figure 19] 10 is a transmission spectrum of a dichroic mirror M5 according to Example 5. [Figure 20] 10 shows a transmission spectrum of a dichroic mirror M6 according to Example 5. [Figure 21] 10 shows a transmission spectrum of a dichroic mirror M7 according to Example 5. [Figure 22] 10 is a transmission spectrum of a dichroic mirror M8 according to Example 5. [Figure 23] 10 is a transmission spectrum of a dichroic mirror M9 according to Example 5. [Figure 24] 10 shows transmission spectra of split light beams C1 to C9 from a nine-split dichroic mirror array according to Example 5. [Figure 25] FIG. 13 is a cross-sectional view showing the configuration of a ten-division dichroic mirror array according to a sixth embodiment. [Figure 26] FIG. 13 is a cross-sectional view showing the configuration of a 12-split dichroic mirror array according to a seventh embodiment. [Figure 27] FIG. 10 is a schematic diagram showing the configuration of a multicolor analyzer equipped with a 13-division dichroic mirror array according to a second embodiment. [Figure 28] FIG. 10 is a schematic diagram showing the configuration of a nine-division dichroic mirror array according to Comparative Example 3. [Figure 29] FIG. 13 is a schematic diagram showing the configuration of a nine-division dichroic mirror array according to an eighth embodiment. [Figure 30] FIG. 10 is a cross-sectional view showing the configuration of a six-division dichroic mirror array according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] In the following, embodiments of the present disclosure will be described using a right-handed XYZ Cartesian coordinate system.

[0020] 1. First embodiment Fig. 1 is a cross-sectional view showing the configuration of a dichroic mirror array according to the first embodiment. As shown in Fig. 1, the dichroic mirror array according to this embodiment includes an A group (first group) consisting of m (m is an integer of 2 or more) dichroic mirrors DA1, DA2, ..., DAm, and a B group (second group) consisting of n (n is an integer of 2 or more) dichroic mirrors DB1, DB2, ..., DBn.

[0021] Generally, a dichroic mirror has an incident surface (i.e., a reflecting surface) and an exit surface, which are parallel to each other (their normals are also parallel to each other), so in this specification, when describing the tilt (direction) at which the dichroic mirror is arranged, the incident surface and the exit surface will be described without distinction. In other words, the incident surface described in this specification can also be replaced with the exit surface.

[0022] Dichroic mirror DA1 is disposed on the Z axis, and dichroic mirrors DA1 to DAm have their incidence surfaces perpendicular to the XZ plane and are arranged parallel to one another along the positive direction of the X axis. The line obtained by projecting the normal to the incidence surfaces of dichroic mirrors DA1 to DAm onto the XZ plane has a negative inclination in the XZ plane. The angle between the normal to the incidence surfaces of dichroic mirrors DA1 to DAm and the Z axis is defined as θ0. In the example shown in FIG. 1, θ0 is 45°, and the normal to the incidence surface of any dichroic mirror among dichroic mirrors DA1 to DAm is parallel to the line Z=-X. In other words, the incidence surfaces of dichroic mirrors DA1 to DAm are parallel to the line Z=X.

[0023] Dichroic mirror DB1 is disposed on the Z axis, and dichroic mirrors DB1 to DBn have their incidence surfaces perpendicular to the XZ plane and are arranged parallel to one another along the negative direction of the X axis. The line obtained by projecting the normal to the incidence surfaces of dichroic mirrors DB1 to DBn onto the XZ plane has a positive inclination in the XZ plane. The angle between the normal to the incidence surfaces of dichroic mirrors DB1 to DBn and the Z axis is defined as θ1. In the example shown in FIG. 1, θ1 is 45°, and the normal to the incidence surface of any dichroic mirror among dichroic mirrors DB1 to DBn is parallel to the line Z=X. In other words, the incidence surfaces of dichroic mirrors DB1 to DBn are parallel to the line Z=-X.

[0024] As described above, the normal to the incident surface of the dichroic mirrors DA1-DAm in Group A and the normal to the incident surface of the dichroic mirrors DB1-DBn in Group B are both parallel to the XZ plane, but are oriented in different directions. In the example shown in Fig. 1, the dichroic mirrors DA1-DAm in Group A and the dichroic mirrors DB1-DBn in Group B are arranged so that the normals to their incident surfaces are oriented perpendicular to each other. Note that θ0 and θ1 are not limited to 45°, and can be set arbitrarily as long as the incident light can be divided.

[0025] As shown in Fig. 1, in the dichroic mirror array according to this embodiment, group B is positioned further towards the positive side of the Z axis than group A. Thus, the dichroic mirror array as a whole has a two-layer structure. Furthermore, dichroic mirrors DA2 and DB2 are located at different positions in the X axis direction, with dichroic mirrors DA2 to DAm having positive X coordinates and dichroic mirrors DB2 to DBn having negative X coordinates. This allows split light beams C(DA2) to C(DAm) and C(DB1) to C(DBn) to be obtained from a single incident light beam C0 by dichroic mirrors DA2 to DAm and dichroic mirrors DB1 to DBn.

[0026] Each dichroic mirror has an optical film formed on at least one surface of a transparent substrate having a refractive index n0. Quartz glass, for example, is used as the transparent substrate. Note that, in the present disclosure, some of the dichroic mirrors constituting the dichroic mirror array may be total reflection mirrors or half mirrors with low wavelength dependency. Therefore, in the present disclosure, dichroic mirrors, total reflection mirrors, and half mirrors may be referred to interchangeably as dichroic mirrors.

[0027] Incident light C0 is incident on dichroic mirror DA1 at an incident angle θ0, traveling from the negative direction to the positive direction of the Z axis. Dichroic mirror DA1 splits incident light C0 into reflected light C(DA1) traveling in the positive direction of the X axis and transmitted light traveling in the positive direction of the Z axis. The reflected light from dichroic mirror DA1 is incident on dichroic mirror DA2 and split into transmitted light traveling in the positive direction of the X axis and reflected light C(DA2) traveling in the positive direction of the Z axis. Similarly, dichroic mirrors DA2 to DAm split the reflected light C(DA1) from dichroic mirror DA1 into (m-1) split light beams (reflected light beams C(DA2) to C(DAm)) traveling in the positive direction of the Z axis.

[0028] Among the dichroic mirrors DA1 to DAm, an arbitrary dichroic mirror is designated as DAj (2≦j≦(m-1)). Light transmitted through the dichroic mirror DAj enters DA(j+1) and is split into transmitted light traveling in the positive direction of the X axis and reflected light C(DA(j+1)) traveling in the positive direction of the Z axis.

[0029] Meanwhile, the transmitted light from dichroic mirror DA1 enters dichroic mirror DB1 and is split into reflected light traveling in the negative direction of the X axis and transmitted light C(DB1) traveling in the positive direction of the Z axis. The reflected light from dichroic mirror DB1 enters dichroic mirror DB2 and is split into transmitted light traveling in the negative direction of the X axis and reflected light C(DB2) traveling in the positive direction of the Z axis. Similarly, the transmitted light from dichroic mirror DA1 is split into n split light beams C(DB1) to C(DBn) traveling in the positive direction of the Z axis by dichroic mirrors DB1 to DBn.

[0030] An arbitrary dichroic mirror among the dichroic mirrors DB1 to DBn is designated as DBk (2≦k≦(n-1)). The light transmitted through the dichroic mirror DBk enters DB(k+1) and is split into transmitted light traveling in the negative direction of the X axis and reflected light C(DB(k+1)) traveling in the positive direction of the Z axis.

[0031] From the above, the total number of split light beams obtained by the dichroic mirror array according to this embodiment is (m+n-1). Since each split light beam has a different wavelength component contained in the incident light C0, detecting each split light beam enables multicolor detection or spectroscopic analysis of the incident light C0.

[0032] The divided light beams C(DAj) and C(DBk) are called divided light beams C(X). When the central wavelength of each divided light beam C(X) is represented by λ(C(X)), the configuration of the dichroic mirror array can be simplified by satisfying any of the following formulas (1) to (8): λ(C(DA2))<…<λ(C(DAm))<λ(C(DB1))<…<λ(C(DBn)) …(1) λ(C(DAm))<…<λ(C(DA2))<λ(C(DB1))<…<λ(C(DBn)) …(2) λ(C(DA2))<…<λ(C(DAm))<λ(C(DBn))<…<λ(C(DB1)) …(3) λ(C(DAm))<…<λ(C(DA2))<λ(C(DBn))<…<λ(C(DB1)) …(4) λ(C(DB1))<…<λ(C(DBn))<λ(C(DA2))<…<λ(C(DAm)) …(5) λ(C(DBn))<…<λ(C(DB1))<λ(C(DA2))<…<λ(C(DAm)) …(6) λ(C(DB2))<…<λ(C(DBn))<λ(C(DAm))<…<λ(C(DA2)) …(7) λ(C(DBn))<…<λ(C(DB2))<λ(C(DAm))<…<λ(C(DA2)) …(8)

[0033] That is, it is preferable to generate split light in the short wavelength band by group A and split light in the long wavelength band by group B, or to generate split light in the short wavelength band by group B and split light in the long wavelength band by group A. In particular, it is easy for the dichroic mirror DA1 to allocate the short wavelength band and the long wavelength band to group A and group B, respectively.

[0034] FIG. 2 is a diagram showing the optical path length required for reflection or transmission by each dichroic mirror. As shown by the dotted squares in FIG. 2, each dichroic mirror is divided into units. The top, right, bottom, and left edges of the unit on the page represent the topmost, rightmost, bottommost, and leftmost edges where a single dichroic mirror is located, respectively. For each split light, the optical path length from the point where it enters the DA1 unit to the point where it exits each dichroic mirror is calculated. The optical path length of the region not included in the unit is ignored here, as it is often the same for conventional dichroic mirror arrays and the dichroic mirror array according to this embodiment.

[0035] Here, to simplify the evaluation of the optical path length, the optical path length per unit is set to 1. Looking at one unit, the transmitted light and reflected light of each dichroic mirror have the same optical path length.

[0036] FIG. 2(a) shows the optical path length required for reflection or transmission of each dichroic mirror in a conventional dichroic mirror array. As shown in FIG. 2(a), a conventional dichroic mirror array is configured with m dichroic mirrors D1 to Dm arranged parallel to one another in a straight line, and produces divided light beams C1 to Cm. As shown in FIG. 2(a), divided light beam C1 has an optical path length of 1 for one unit, divided light beam C2 has an optical path length of 2 for two units, and so on, with divided light beam Cm having an optical path length of m for m units. In other words, the maximum optical path length in a conventional dichroic mirror array is m.

[0037] FIG. 2(b) shows the optical path length required for reflection or transmission of each dichroic mirror in the dichroic mirror array according to this embodiment. Unlike FIG. 2(a), FIG. 2(b) shows units in the area where the split light propagates (above DA2 to DAm) even though there are no dichroic mirrors due to the dichroic mirror array's two-layer structure. This is because the sensors that detect the split light are arranged parallel to the dichroic mirror arrangement direction. As shown in FIG. 2(b), the maximum optical path length of the dichroic mirror array according to this embodiment is the larger of (m+1) or (n+1). In contrast, as shown in FIG. 2(a), in the case of a conventional dichroic mirror array, the maximum optical path length required to obtain (m+n-1) split light beams is m+n-1.

[0038] Therefore, the dichroic mirror array according to this embodiment can increase the maximum optical path length by either (m+1) / (m+n-1) times or (n+1) / (m+n-1) times, whichever is larger, compared to a conventional dichroic mirror array. Therefore, when m ≈ n, the maximum optical path length can be reduced to approximately half. For example, when m = n = 10, the maximum optical path length can be reduced to 0.53 times.

[0039] On the other hand, the minimum optical path length is 2 in the dichroic mirror array according to this embodiment and 1 in the conventional dichroic mirror array. Therefore, the difference between the maximum optical path length and the minimum optical path length (optical path length difference) changes almost in proportion to the maximum optical path length. In this way, by using the configuration of the dichroic mirror array according to this embodiment, the difference between the maximum optical path length and the minimum optical path length can be reduced to approximately half.

[0040] Fig. 3 is a diagram showing the results of a comparison of optical path lengths for dichroic mirror arrays with division numbers of 3 to 13. Fig. 3 shows the maximum optical path length and the optical path length difference between the maximum and minimum optical path lengths for each dichroic mirror array, for both the conventional example and this embodiment.

[0041] As is clear from Fig. 3, the maximum optical path length of this embodiment is reduced compared to the conventional example for all dichroic mirror arrays with a division number of 5 or more. Furthermore, the optical path length difference of this embodiment is reduced compared to the conventional example for all dichroic mirror arrays with a division number of 3 or more.

[0042] Furthermore, as the number of divisions increases, the difference in maximum optical path length increases, and the effect of this embodiment becomes more pronounced. For example, in a dichroic mirror array with 9 divisions, the maximum optical path length is reduced from 9 in the conventional example to 6, and the optical path length difference is reduced from 8 in the conventional example to 4. In this way, the reduction in both the maximum optical path length and the optical path length difference is greater than when the number of divisions is 7, and it can be seen that the effect of this embodiment becomes even greater as the number of divisions increases.

[0043] As described above, the dichroic mirror array according to this embodiment includes Group A dichroic mirrors DA1-DAm and Group B dichroic mirrors DB1-DBn, which are oriented in different directions, and the dichroic mirrors DA1 and DB1 are arranged along the Z-axis. This configuration minimizes the increase in the maximum optical path length of the incident light, even if the number of dichroic mirrors is increased to increase the number of splits of the incident light. This allows for highly sensitive, highly accurate, and independent multicolor detection of the incident light. Furthermore, the maximum optical path length of the incident light can be reduced without increasing or decreasing the number of dichroic mirrors or the number of splits of the incident light, enabling even higher levels of highly accurate and independent multicolor detection while maintaining highly sensitive multicolor detection of the incident light.

[0044] [Comparative Example 1] Next, a comparative example and an example of the first embodiment will be described. 4A and 4B are diagrams illustrating a dichroic mirror array according to Comparative Example 1. Fig. 4A is a cross-sectional view illustrating the configuration of the dichroic mirror array according to Comparative Example 1.

[0045] As shown in Fig. 4(a), the dichroic mirror array according to Comparative Example 1 includes dichroic mirrors M1 to M7 with different spectral characteristics, and divides incident light C0 into seven beams. The dichroic mirrors M1 to M7 are inclined at 45° with respect to the XY plane and the YZ plane, and are arranged parallel to one another at approximately equal intervals along the positive direction of the X axis. Note that the effect of the thickness of each dichroic mirror M1 to M7 is ignored.

[0046] If the width of dichroic mirrors M1 to M7 parallel to the plane of the paper in Figure 4(a) is α, the arrangement interval between each dichroic mirror is α / √2. In other words, where k is an integer between 1 and 6, the right end of dichroic mirror Mk and the left end of dichroic mirror M(k+1) are located at the same position in the X-axis direction.

[0047] Incident light C0 travels in the positive direction of the Z axis and enters dichroic mirror M1, where it is split into reflected light traveling in the positive direction of the X axis and transmitted light traveling in the positive direction of the Z axis, i.e., divided light C1. The reflected light then enters dichroic mirror M2 and is split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., divided light C2. Similarly, for 3≦k≦6, transmitted light traveling in the positive direction of the X axis after passing through dichroic mirror M(k-1) enters dichroic mirror Mk and is split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., divided light Ck. Transmitted light traveling in the positive direction of the X axis after passing through dichroic mirror M6 enters dichroic mirror M7, where it generates reflected light traveling in the positive direction of the Z axis, i.e., divided light C7. It is possible to eliminate light transmitted through the dichroic mirror M7 by making the dichroic mirror M7 a total reflection mirror.

[0048] As a result, seven divided beams C1 to C7 traveling in the positive direction of the Z axis are obtained. Because the divided beams C1 to C7 contain different wavelength components that were contained in the incident beam C0, multicolor detection of the incident beam C0 is possible by detecting each of the divided beams C1 to C7.

[0049] 4(b) is a diagram showing the optical path length required for reflection or transmission by each dichroic mirror. The units indicated by the dotted squares are the same as those in FIG. 2, so their explanation will be omitted.

[0050] 4(b), the divided light C1 has an optical path length of 1 for one unit, the divided light C2 has an optical path length of 2 for two units, and similarly, the divided light C7 has an optical path length of 7 for seven units. Therefore, in the dichroic mirror array according to Comparative Example 1, the maximum optical path length is 7, the minimum optical path length is 1, and the difference between the maximum and minimum optical path lengths is 6.

[0051] [Example 1] 5A and 5B are diagrams illustrating a dichroic mirror array according to Example 1. Fig. 5A is a cross-sectional view illustrating the configuration of the dichroic mirror array according to Example 1.

[0052] 5(a), the dichroic mirror array according to the first embodiment includes eight dichroic mirrors M1 to M8 having different spectral characteristics, and can split incident light C0 into seven beams C1 to C7. The dichroic mirrors M1 to M4 are group A, and the dichroic mirrors M5 to M8 are group B.

[0053] The dichroic mirrors M1 to M4 are inclined at 45° with respect to the XY plane and the YZ plane, and are arranged parallel to one another at approximately equal intervals along the positive direction of the X axis. The normal to the entrance surface of each of the dichroic mirrors M1 to M4 is parallel to the XZ plane and is inclined at -45° with respect to the XZ plane.

[0054] The dichroic mirrors M5 to M8 are inclined at 45° with respect to the XY plane and the YZ plane, and are arranged parallel to one another at approximately equal intervals along the negative direction of the X axis. The normal to the entrance surface of the dichroic mirrors M5 to M8 is parallel to the XZ plane and is inclined at 45° in the XZ plane. That is, the dichroic mirrors M1 to M4 and the dichroic mirrors M5 to M8 are arranged so that they face each other and their normal lines intersect at right angles.

[0055] The dichroic mirror M1 and the dichroic mirror M5 are located at the same position in the X-axis direction, and the dichroic mirror M5 is located further in the positive direction of the Z-axis than the dichroic mirror M1. Therefore, the dichroic mirrors M5 to M8 are located further in the positive direction of the Z-axis than the dichroic mirrors M1 to M4. In this way, the dichroic mirror array according to the first embodiment has a two-layer structure as a whole.

[0056] If the width of the dichroic mirrors M1 to M8 parallel to the XZ plane is α, then the arrangement intervals of the dichroic mirrors M1 to M4 and M5 to M8 are each α / √2. The distance between the center of the dichroic mirror M1 and the center of the dichroic mirror M5 is also α / √2.

[0057] Incident light C0 travels in the positive direction of the Z axis and strikes dichroic mirror M1 at an incident angle of 45°, where it is split into reflected light traveling in the positive direction of the X axis and transmitted light traveling in the positive direction of the Z axis. The reflected light from dichroic mirror M1 is then struck by dichroic mirror M2 at an incident angle of 45° and split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C1. The transmitted light from dichroic mirror M2 is then struck by dichroic mirror M3 at an incident angle of 45° and split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C2. The transmitted light from dichroic mirror M3 is then struck by dichroic mirror M4 at an incident angle of 45°, where it generates reflected light traveling in the positive direction of the Z axis, i.e., split light C3. Here, the transmitted light from dichroic mirror M4 is ignored.

[0058] Meanwhile, the light transmitted through dichroic mirror M1 is incident on dichroic mirror M5 at an incident angle of 45° and split into reflected light traveling in the negative direction of the X axis and transmitted light traveling in the positive direction of the Z axis, i.e., split light C4. The light reflected from dichroic mirror M5 is incident on dichroic mirror M6 at an incident angle of 45° and split into transmitted light traveling in the negative direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C5. The light transmitted through dichroic mirror M6 is incident on dichroic mirror M7 at an incident angle of 45° and split into transmitted light traveling in the negative direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C6. The light transmitted through dichroic mirror M7 is incident on dichroic mirror M8 at an incident angle of 45° and generates reflected light traveling in the positive direction of the Z axis, i.e., split light C7. Here, the light transmitted through dichroic mirror M8 is ignored. The dichroic mirrors M4 and M8 may be total reflection mirrors.

[0059] In this way, seven divided beams C1 to C7 traveling in the positive direction of the Z axis are obtained. Because the divided beams C1 to C7 contain different wavelength components that were contained in the incident beam C0, multicolor detection of the incident beam C0 becomes possible by detecting each of the divided beams C1 to C7.

[0060] 5(b) is a diagram showing the optical path length required for reflection or transmission by each dichroic mirror. The units indicated by the dotted squares are the same as those described above, and therefore their explanation will be omitted.

[0061] As shown in Figure 5(b), split light C1 is three units long and has an optical path length of 3, split light C2 is four units long and has an optical path length of 4, split light C3 is five units long and has an optical path length of 5, split light C4 is two units long and has an optical path length of 2, split light C5 is three units long and has an optical path length of 3, split light C6 is four units long and has an optical path length of 4, and split light C7 is five units long and has an optical path length of 5. Therefore, the maximum optical path length is 5, the minimum optical path length is 2, and the difference between the maximum and minimum optical path lengths is 3.

[0062] A comparison of the evaluation results of the optical path lengths of Comparative Example 1 and Example 1 shows that, although both dichroic mirror arrays perform seven-color detection using the same seven-division method, the maximum optical path length of the dichroic mirror array according to Example 1 can be reduced to 5 from the maximum optical path length of 7 in Comparative Example 1, and the difference between the maximum and minimum optical path lengths can be reduced to 3 from 6 in Comparative Example 1. In this way, the dichroic mirror array according to Example 1 enables seven-color detection with high accuracy, high sensitivity, and low crosstalk.

[0063] 4 and 5 show cross-sectional views of the dichroic mirror array, and therefore only one incident light beam C0 is shown. However, multiple incident light beams C0 may be arranged in the direction perpendicular to the plane of the cross-sectional view (Y-axis direction), and each of the multiple incident light beams C0 may be split into seven parallel beams by the dichroic mirror array to generate split light beams C1 to C7.

[0064] [Example 2] 6 is a schematic diagram showing the configuration of a multi-color detection device according to Example 2. The multi-color detection device according to Example 2 is a device that performs seven-color detection of light emitted from one light-emitting point P using the dichroic mirror array according to Example 1.

[0065] Incident light C0 is a light beam obtained by collecting light emitted from light-emitting point P with a collecting lens L. In FIG. 5, each light ray is shown as a line, but in FIG. 6, each light ray is shown as a bundle (light beam) with a width. FIG. 6(a) is a cross-sectional view of the multi-color detection device according to this embodiment taken along the XZ plane. FIG. 6(b) is a view seen from the arrow A in FIG. 6(a).

[0066] As shown in FIG. 6(a), the multicolor detection device according to the second embodiment includes dichroic mirrors M1 to M8, a condenser lens L, a sensor array, and a light-emitting point P.

[0067] The dichroic mirrors M1 to M8 have the same configuration as in the first embodiment, and therefore a description thereof will be omitted.

[0068] The sensor array has seven sensor elements arranged parallel to the XY plane along the X-axis direction, and each sensor element is located on the positive Z-axis side of dichroic mirrors M1 to M8. The seven split light beams C1 to C7 travel in the positive Z-axis direction, enter the sensor surface S of each sensor element, and are detected by the sensor array. However, in Figure 6, the boundaries between the sensor surfaces S of the multiple sensor elements are not shown. The sensor array is a single line sensor or area sensor. Each of the split light beams C1 to C7 is a component of the incident light C0 in a different wavelength band, i.e., a different color component. Therefore, by measuring them simultaneously and independently, it is possible to detect the seven colors of the incident light C0.

[0069] In the second embodiment, since there is one light-emitting point P, the width of each dichroic mirror in the Y-axis direction only needs to be larger than the maximum width of the luminous fluxes of the incident light C0 and the divided lights C1 to C7, as shown in FIG. 6(b).

[0070] As described above, the multi-color detection device of Example 2, like Example 1, can reduce the maximum optical path length and the optical path length difference compared to when using the dichroic mirror array of Comparative Example 1, and therefore can perform multi-color detection of the light emitted from the light-emitting point P with high accuracy and high sensitivity.

[0071] [Example 3] FIG. 7 is a schematic diagram showing the configuration of a multi-color detection device DS according to Example 3. The multi-color detection device DS according to Example 3 is a multi-color detection device that uses a dichroic mirror array similar to that of Example 1 to detect seven colors of light emitted from p (2≦p) light-emitting points P, respectively. In Example 3, seven colors of light emitted from four light-emitting points P1 to P4 are detected, respectively. FIG. 7(a) is a cross-sectional view of the multi-color detection device DS according to this example taken along the XZ plane. FIG. 7(b) is a view seen from the arrow A in FIG. 7(a).

[0072] As shown in FIGS. 7(a) and 7(b), the multicolor detection device DS according to the third embodiment includes dichroic mirrors M1 to M8, condenser lenses L1 to L4, an area sensor, and light-emitting points P1 to P4.

[0073] The light emitted from the light-emitting points P1 to P4 is condensed by the condenser lenses L1 to L4, respectively, to become incident light C0-1 to C0-4. Note that the number of light-emitting points P is not limited to four, and can be any number.

[0074] The dichroic mirrors M1 to M8 have a larger width in the Y-axis direction than the dichroic mirror in Example 1 so that the incident light beams C0-1 to C0-4 can be commonly incident on them. The dichroic mirrors M1 to M8 split the incident light beams C0-1 to C0-4 into seven beams each, obtaining 28 split beams C1-1 to C7-4.

[0075] The area sensors are arranged parallel to the XY plane on the positive Z-axis side of the dichroic mirrors M1 to M8. The 28 divided beams C1-1 to C7-4 are commonly incident on the sensor surface S of one area sensor and detected by the area sensor.

[0076] In this disclosure, the term "common" may be used to mean that one optical element is used for multiple (M) light-emitting points, light beams, or split beams (M:1 correspondence). Also, the term "individual" may be used to mean that one optical element is used for one light-emitting point, light beam, or split beam (1:1 correspondence).

[0077] To individually detect the 28 split beams C1-1 to C7-4, a sensor array is used that has a total of 28 sensor elements arranged in four in the Y-axis direction and seven in the X-axis direction. Each sensor element is arranged parallel to the XY plane on the positive Z-axis side of the dichroic mirrors M1 to M8. Each of the 28 split beams C1-1 to C7-4 is incident on the sensor surface S of the sensor element and detected by the sensor array.

[0078] As described above, the multi-color detection device DS of Example 3, like Example 1, can reduce the maximum optical path length and optical path length difference for multiple incident light beams C0-1 to C0-4 compared to when using the dichroic mirror array of Comparative Example 1, and therefore can perform multi-color detection of light emissions from multiple light-emitting points P with high accuracy, high sensitivity, and low crosstalk.

[0079] [Example 4] 8(a) is a schematic diagram showing the configuration of a capillary array DNA sequencer according to Example 4. The capillary array DNA sequencer according to Example 4 is an analytical device that uses the multicolor detection device DS according to Example 3 and detects fluorescence from DNA fragments.

[0080] The capillary array DNA sequencer comprises a laser light source 1, a valve 4, a cathode side buffer solution 7, a cathode 8, an anode side buffer solution 9, an anode 10, a pump block 11, a syringe 12, a power supply 13, a capillary array CA, and a multicolor detection device DS.

[0081] A laser light source 1 irradiates a laser beam 2 onto a laser beam irradiation position 3 of the capillary array CA. The laser beam irradiation position 3 is a position a certain distance from the sample injection end 5 where the DNA fragments have been electrophoresed.

[0082] The capillary array CA has multiple capillaries, which are arranged on an XY plane near the laser beam irradiation position 3. The sample injection end 5 of the capillary array CA is immersed in a cathode-side buffer solution 7, and the sample elution end 6 is immersed in an anode-side buffer solution 9 via a pump block 11.

[0083] The pump block 11 is filled with a polymer solution. A syringe 12 and a valve 4 are connected to the pump block 11. By applying pressure to the polymer solution inside the pump block 11 using the syringe 12 while the valve 4 is closed, the polymer solution can be filled inside the capillary array CA from the sample elution end 6 toward the sample injection end 5.

[0084] The cathode 8 is immersed in the cathode side buffer solution 7, and the anode 10 is immersed in the anode side buffer solution 9. A power supply 13 applies a high voltage between the cathode 8 and the anode 10.

[0085] After filling the capillary array CA with a polymer solution, the valve 4 is opened, a different sample is injected into each capillary through the sample injection end 5, and capillary electrophoresis can be performed by applying a high voltage between the cathode 8 and the anode 10. DNA fragments contained in the sample and labeled with four color fluorophores migrate electrophoretically from the sample injection end 5 to the sample elution end 6.

[0086] Fig. 8(b) is an enlarged view of the multi-color detection device DS shown in Fig. 8(a). As shown in Fig. 8(b), the capillary array CA includes four capillaries CA1 to CA4. The number of capillaries is not limited to four, and can be any number.

[0087] The capillaries CA1 to CA4 are arranged along the Y-axis direction on the XY plane, and their coatings are removed at the laser beam irradiation position 3. The DNA fragments are labeled with four color fluorophores, undergo electrophoresis inside each of the capillaries CA1 to CA4, and are excited to emit fluorescence when passing through the laser beam irradiation position 3. Therefore, the insides of the capillaries CA1 to CA4 at the laser beam irradiation position 3 become light-emitting points P1 to P4, respectively.

[0088] The multi-color detection device DS has the same configuration as the multi-color detection device DS according to Example 3, and therefore a description thereof will be omitted. The multi-color detection device DS is disposed on the positive Z-axis side of the capillary array CA.

[0089] As shown in Figure 8(b), the laser beam 2 emitted from the laser light source 1 travels along the XY plane in the positive direction of the Y axis, irradiating the laser beam irradiation positions 3 of the capillaries CA4, CA3, CA2 and CA1, i.e., the light-emitting points P4, P3, P2 and P1, all at once.

[0090] DNA fragments labeled with four color fluorophores are excited by laser beam 2 as they pass through laser beam irradiation position 3. The resulting light emitted from light-emitting points P1 to P4 is subjected to seven-color detection using multicolor detection device DS. The wavelength of laser beam 2 is 505 nm, and the wavelengths of the four color fluorescence (maximum emission wavelengths) are 540 nm, 570 nm, 600 nm, and 630 nm.

[0091] As described above, while the analysis target is four-color fluorescence, the multicolor detection device DS can detect seven colors, making it possible to detect four-color fluorescence with high accuracy. In this way, the capillary array DNA sequencer of this embodiment is capable of analysis with high accuracy, high sensitivity, and low crosstalk.

[0092] [Example 5] 9 is a cross-sectional view showing the configuration of a dichroic mirror array according to Example 5. Configurations not specifically described are the same as those in Example 1. The dichroic mirror array according to Example 5 includes ten dichroic mirrors M1 to M10, and can split incident light C0 into nine parts to detect nine colors. Although not shown in the figure, the dichroic mirrors M1 to M5 are group A, and the dichroic mirrors M6 to M10 are group B.

[0093] The dichroic mirror M5 located at the end of Group A in the positive direction of the X axis and the dichroic mirror M10 located at the end of Group B in the negative direction of the X axis have the same spectral characteristics. The dichroic mirrors M5 and M10 may be, for example, total reflection mirrors.

[0094] 9, the dichroic mirror array according to Example 5 differs from Examples 1 to 4 in that it includes a band-pass filter BP (first filter) on the negative Z-axis side of the dichroic mirror M1. The rest of the configuration is the same as that of the dichroic mirror array according to Example 1, and therefore a description thereof will be omitted.

[0095] The shape of the bandpass filter BP is the same as that of the dichroic mirrors M1 to M10. The bandpass filter BP is arranged parallel to the XY plane and on the negative Z-axis side of the dichroic mirror M1. In other words, the normals to the entrance and exit surfaces of the bandpass filter BP are parallel to the Z-axis. By including the bandpass filter BP, light in a predetermined wavelength band among the multiple wavelength bands contained in the incident light C0 is transmitted and made incident on the dichroic mirror M1, thereby enabling multicolor detection of only the light in the desired wavelength band.

[0096] Incident light C0 travels in the positive direction of the Z axis and strikes bandpass filter BP at an angle of incidence of 0°, generating transmitted light traveling in the positive direction of the Z axis. The transmitted light from bandpass filter BP is incident on dichroic mirror M1 at an angle of incidence of 45° and split into reflected light traveling in the positive direction of the X axis and transmitted light traveling in the positive direction of the Z axis. The reflected light from dichroic mirror M1 is incident on dichroic mirror M2 at an angle of incidence of 45° and split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C1. Dichroic mirrors M2 to M5 similarly produce split light C1 to C4. Note that the transmitted light from dichroic mirror M5 is ignored.

[0097] Meanwhile, the light transmitted through dichroic mirror M1 is incident on dichroic mirror M6 at an incident angle of 45° and is split into reflected light traveling in the negative direction of the X axis and transmitted light traveling in the positive direction of the Z axis, i.e., split light C5. The light reflected from dichroic mirror M6 is incident on dichroic mirror M7 at an incident angle of 45° and is split into transmitted light traveling in the negative direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., split light C6. Similarly, split light C5 to C9 are obtained by dichroic mirrors M6 to M10. Note that the light transmitted through dichroic mirror M10 will be ignored.

[0098] As described above, nine divided beams C1 to C9 traveling in the positive direction of the Z axis are obtained by the dichroic mirror array according to Example 5. Since the divided beams C1 to C9 have different wavelength components of the incident beam C0, nine colors of the incident beam C0 can be detected by detecting each of the divided beams C1 to C9.

[0099] Comparative Example 2 The dichroic mirror array of Comparative Example 2 was the same as Comparative Example 1, except that the number of dichroic mirrors was nine, designated dichroic mirrors M1 to M9, and a bandpass filter BP was placed parallel to the XY plane on the negative Z-direction side of dichroic mirror M1.

[0100] <Evaluation of maximum optical path length and optical path length difference> Next, with reference to FIGS. 10 to 13, the results of practical calculations of the maximum optical path length and the optical path length difference for the nine-color detection device using the dichroic mirror array according to Example 5 or Comparative Example 2 will be described.

[0101] Hereinafter, the device using the dichroic mirror array of Example 5 will be referred to as the "9-color detection device of this example," and the device using the dichroic mirror array of Comparative Example 2 will be referred to as the "9-color detection device of the comparative example."

[0102] Although not shown in the figures, the nine-color detection devices of this example and comparative example include a condenser lens L, the dichroic mirror array of Example 5 or Comparative Example 2, and an area sensor. In the nine-color detection devices of this example and comparative example, a light beam obtained by condensing light emitted from one or more light-emitting points P with the condenser lens L is used as incident light C0, nine split light beams C1 to C9 are generated by the dichroic mirror array, and the split light beams C1 to C9 are incident perpendicularly on the sensor surface S of the area sensor and detected.

[0103] 3, in the case of nine divisions, the maximum optical path length of the nine-color detection device of the comparative example is 9, the optical path length difference is 8, and the optical path lengths of each of the divided lights C1 to C9 are 1 to 9. In contrast, the maximum optical path length of the nine-color detection device of this embodiment is 6, the optical path length difference is 4, and the optical path lengths of each of the divided lights C1 to C9 are 2 to 6. Here, as an example, if an optical path length of 1 is converted to 2.5 mm, the optical path lengths of the nine-color detection device of the comparative example are 2.5 to 22.5 mm, and the optical path lengths of the nine-color detection device of this embodiment are 5.0 to 15.0 mm.

[0104] For each of the nine-color detection devices, the size of the spots formed on the sensor surface S by the split light beams C1 to C9 was determined by ray tracing simulation. Furthermore, we evaluated the effect of mutual crosstalk on the accuracy of spectroscopic analysis when detecting split light beams C1 to C9 from a single light-emitting point, and the effect of mutual crosstalk on independent measurements when detecting split light beams Ck (1≦k≦9) from multiple light-emitting points. The results are shown in Figures 10 and 11.

[0105] Figure 10 is a model diagram for determining the relationship between the size of the light-emitting point P, the focal length f of the condenser lens L, the light-emitting point distance g, the sensor distance h, and the spot size W through a ray tracing simulation. The light-emitting point distance g is the distance between the light-emitting point P and the condenser lens L. The sensor distance h is the optical distance (optical path length) between the condenser lens L and the sensor surface S. The spot size W is the size of the spot projected onto the sensor surface S by the light beam obtained by condensing the light emitted from the light-emitting point P with the condenser lens L.

[0106] A light-emitting point P is placed on the left, a condenser lens L on the right of that, and the sensor surface S of the sensor on the right of that. Figure 10(a) shows an example of a state where there is no light emission, and Figure 10(b) shows an example of a state where there is light emission. Figure 10(b) depicts only the light rays emitted from the light-emitting point P that are condensed by the condenser lens L. As an example, the light-emitting point P is circular with a diameter of d = 0.05 mm. The condenser lens L has an effective diameter of D = 1 mm and a focal length of f = 1.4 mm. The condenser lens L is selected to have a flat surface on the left side (the light-emitting point side) and an aspherical surface on the right side (the sensor side), with relatively little aberration.

[0107] The light-emitting point distance g was changed in 0.01 mm increments within the range of 1.40 mm ≦ g ≦ 1.70 mm, and the sensor distance h for each light-emitting point distance g was changed in 2.5 mm increments within the range of 2.5 mm ≦ h ≦ 30 mm, and the spot size W at each sensor distance h was calculated. The spot size W was calculated as the total width of the area in the spot intensity distribution where the intensity was 1% or more of the maximum intensity.

[0108] Figure 11 is a graph showing the calculation results of the model in Figure 10. In Figure 11, the horizontal axis represents the sensor distance h and the vertical axis represents the spot size W, with the light-emitting point distance g as a parameter. However, the horizontal axis only shows the range of 2.5 mm ≤ h ≤ 22.5 mm. The solid line represents the case where the first decimal place of the light-emitting point distance g is an even number, and the dotted line represents the case where the first decimal place of the light-emitting point distance g is an odd number.

[0109] Because the light-emitting point P has a finite size (d = 0.05 mm > 0 mm), under any conditions, the light beam (beam) emitted from the light-emitting point P and collected by the collecting lens L will never be a perfectly parallel beam (beam). When the sensor distance h is sufficiently large, the spot size W increases with the sensor distance h. The light-emitting point distance g = 1.40 mm, which is the condition where the light-emitting point P is located at the focal point of the collecting lens L and is closest to a parallel beam (beam), minimizes the spot size W at infinity, i.e., when the sensor distance h is sufficiently large. Here, the term "minimum" means that the spot size W minimizes when the light-emitting point distance g is changed at the same sensor distance h. The state where the spot size W is minimized at the same sensor distance h corresponds to the state where the beam of light emitted from the light-emitting point P and collected by the collecting lens L is just focused at that sensor distance h.

[0110] As shown in FIG. 11, as the light-emitting point distance g increases, the sensor distance h at which the spot size W is smallest decreases, compared to when the light-emitting point distance g is 1.40 mm. For example, when g = 1.50 mm and h = 20.0 mm, the spot size reaches its smallest value W = 0.70 mm. When g = 1.54 mm and h = 15.0 mm, the spot size reaches its smallest value W = 0.52 mm. When g = 1.62 mm and h = 10.0 mm, the spot size reaches its smallest value W = 0.34 mm. And when g = 1.70 mm and h = 7.5 mm, the spot size reaches its smallest value W = 0.26 mm.

[0111] When the optical path length h of each split light beam generated by the dichroic mirror array is h(min)≦h≦h(max), selecting the light-emitting point distance g that minimizes the maximum spot size W within h(min)≦h≦h(max) minimizes the overlap between different spots, providing the most favorable conditions for high-precision multicolor detection or independent measurement of different light-emitting points. As can be seen from Figure 11, the maximum spot size W within h(min)≦h≦h(max) is minimized when the light-emitting point P is just focused at h=h(max).

[0112] Another finding obtained from Figure 11 is that, for the curves with fixed light-emitting point distances g, the spot size W changes gradually to the left (in the direction in which the sensor distance h becomes smaller) of the sensor distance h that provides just focus, whereas the spot size W changes rapidly to the right (in the direction in which the sensor distance h becomes larger). On the other hand, when the sensor distance h is fixed and the light-emitting point distance g that provides just focus is the boundary, the spot size W changes gradually as the light-emitting point distance g is made smaller, whereas the spot size W changes rapidly as the light-emitting point distance g is made larger. Therefore, when designing a multi-color detection device, it may be preferable to set the sensor distance h and the light-emitting point distance g to be smaller than their optimal values, taking into account installation errors of each element.

[0113] As described above, the optimal condition for the nine-segment dichroic mirror array of Comparative Example 2 is when the optical path length h is 2.5 mm≦h≦22.5 mm, and the light-emitting point P is just focused at h=22.5 mm, i.e., when g=1.49 mm, the maximum spot size W is minimized. In fact, as shown in FIG. 11 , when g=1.49 mm and h=22.5 mm, the spot size W reaches its minimum value of W=0.79 mm. Furthermore, when 2.5 mm≦h≦22.5 mm and h=2.5 mm, the spot size W reaches its minimum value of W=0.51 mm. In contrast, for example, when g=1.50 mm, the spot size W at h=2.5 mm is smaller than when g=1.49 mm, but when h=22.5 mm, the spot size W is larger than when g=1.49 mm, reaching W=0.84 mm. Alternatively, when g = 1.48 mm, the spot size W is larger over the entire range of 2.5 mm ≦ h ≦ 22.5 mm than when g = 1.49 mm. From the above, the optimal condition is when g = 1.49 mm, that is, when the light-emitting point is just focused at h = 22.5 mm, and the spot size W is 0.51 mm ≦ W ≦ 0.79 mm for 2.5 mm ≦ h ≦ 22.5 mm.

[0114] Similarly, the optimum condition for the nine-segment dichroic mirror array according to Example 5 is when the optical path length h is 5.0 mm≦h≦15.0 mm, and the light-emitting point P is just focused at h=15.0 mm, i.e., when g=1.54 mm, the maximum spot size W is minimized. In fact, as shown in FIG. 11 , when g=1.54 mm and h=15.0 mm, the spot size reaches its minimum value W=0.52 mm. Furthermore, when 5.0 mm≦h≦15.0 mm and h=7.5 mm, the spot size W reaches its minimum value W=0.47 mm. On the other hand, when g=1.55 mm, for example, the spot size W is smaller at 5.0 mm≦h≦12.5 mm than when g=1.54 mm, but when h=15.0 mm, the spot size W is larger than when g=1.54 mm, reaching W=0.55 mm. Alternatively, when g = 1.53 mm, the spot size W is larger over the entire range of 5.0 mm ≦ h ≦ 15.0 mm than when g = 1.54 mm. From the above, the optimal condition is when g = 1.54 mm, that is, when h = 15.0 mm and the light-emitting point P is just focused, and when 5.0 mm ≦ h ≦ 15.0 mm, the spot size W is 0.47 mm ≦ W ≦ 0.52 mm.

[0115] Fig. 12 shows the signal intensity distribution on a line passing through the center of the spot obtained when the sensor is placed at the position of optical path length h, with optical path length h as a parameter. The horizontal axis represents the spatial coordinate on the line, with the center of the spot set to zero, and the vertical axis represents the relative signal intensity.

[0116] The volume of the rotationally symmetric body about the central axis of each signal intensity distribution (a straight line passing through zero on the horizontal axis and parallel to the vertical axis) corresponds to the total intensity of each spot and is equal to each other. The width of the region having a signal intensity of 1% or more of the signal intensity on the central axis of each signal intensity distribution is shown in Figure 11 as the spot size W.

[0117] 12(a) shows the signal intensity distribution of the spot when the optical path length h is 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, 20.0, and 22.5 mm under the optimal condition of the nine-segment dichroic mirror array of Comparative Example 2, i.e., when g = 1.49 mm. Since the light-emitting point P is just focused at h = 22.5 mm, the signal intensity distribution at h = 22.5 mm is closest to a rectangular shape.

[0118] 12(b) shows the signal intensity distribution of the spot when the optical path length h is h=5.0, 7.5, 10.0, 12.5, and 15.0 mm under the optimal condition of the nine-segment dichroic mirror array according to Example 5, i.e., when g=1.54 mm. Since the light-emitting point P is just focused at h=15.0 mm, the signal intensity distribution at h=15.0 mm is closest to a rectangular shape.

[0119] As shown in Figure 12, the longer the maximum optical path length of the dichroic mirror array and the larger the optical path length difference, the more severe the fluctuations in the signal intensity distribution of the spots obtained using the dichroic mirror array become, making it even more difficult to simultaneously measure spots at each optical path length than in Figure 11.

[0120] For example, in Figure 12(a), when h = 10.0 mm, the signal intensity of the central axis is 12.4, whereas when h = 22.5 mm, the signal intensity of the central axis is 2.0. Therefore, it is necessary to simultaneously measure multiple different spots with a signal intensity ratio of 12.4 / 2.0 = 6.2. If the signal intensity ratio is large, the large signal intensity will exceed the saturation level of the sensor, while the small signal intensity will not reach the saturation level, resulting in a problem of a reduced effective dynamic range of signal measurement.

[0121] In contrast, in Figure 12(b), when h = 10.0 mm, the signal strength of the central axis is 16.6, but when h = 15.0 mm, the signal strength of the central axis is 4.9. Therefore, the signal strength ratio is 16.6 / 4.9 = 3.4, which is about half of the value in Figure 12(a), making it possible to avoid the above-mentioned problems.

[0122] Figure 13 compares the signal intensity distribution for g = 1.49 mm, h = 22.5 mm in Figure 12(a) with the signal intensity distribution for g = 1.54 mm, h = 15.0 mm in Figure 12(b), normalized for maximum intensity. While the vertical axis in Figure 13(a) is scaled from 0.00 to 1.00, the vertical axis in Figure 13(b) is scaled from 0.00 to 0.10, with the vertical axis of Figure 13(a) being enlarged.

[0123] As described above and shown in Figure 13, the spot size W is the width of the region where the normalized signal intensity is 1% or greater of the maximum intensity, i.e., 0.01 or greater. When g = 1.49 mm and h = 22.5 mm, W = 0.79 mm. When g = 1.54 mm and h = 15.0 mm, W = 0.52 mm. As the spot size W increases, different spots generated by the dichroic mirror array blend together on the sensor, resulting in crosstalk between different light-emitting points and reduced spectral accuracy in multicolor detection. For example, let's assume that measurement of spot A in the signal intensity distribution shown in Figure 13 is performed at the center of spot A, i.e., at zero on the horizontal axis. Let's also assume that the center of spot B, originating from an adjacent light-emitting point, is located at 0.52 mm / 2 = 0.26 mm, and measurement of spot B is performed at the center of spot B. In this case, when g = 1.54 mm and h = 15.0 mm, the measurement signal from spot B contains a signal with an intensity of 1% of the maximum intensity of spot A. If the maximum intensities of spots A and B are equal, this corresponds to 1% crosstalk. In contrast, when g = 1.49 mm and h = 22.5 mm, the measurement signal from spot B contains a signal with an intensity of 100% of the maximum intensity of spot A, i.e., a signal with an intensity equal to the maximum intensity of spot A. This corresponds to 100% crosstalk. From the above, it can be seen that as the spot size W increases, crosstalk between different light-emitting points can rapidly increase. Therefore, reducing the maximum optical path length using the dichroic mirror array of this embodiment, and thereby reducing the spot size W, is highly effective in reducing crosstalk and improving spectroscopic accuracy in multicolor detection.

[0124] Next, we will show the specific design of the components of the dichroic mirror array according to Example 5. Here, we will assume that a capillary array DNA sequencer similar to that of Example 4 is used, four capillaries are irradiated simultaneously with a 505 nm laser beam, and nine colors of fluorescence emitted from the inside of each capillary are detected using the dichroic mirror array according to Example 5.

[0125] The basic design aims to have the split light C1 to C9 from the dichroic mirror array of Example 5 mainly contain light components in the following wavelength bands, that is, to transmit light in the following wavelength bands for the incident light C0. C1: Wavelength band 520-540nm C2: Wavelength band 540-560nm C3: Wavelength band 560-580nm C4: Wavelength band 580-600nm C5: Wavelength band 600-620nm C6: Wavelength band 620-640nm C7: Wavelength band 640-660nm C8: Wavelength band 660-680nm C9: Wavelength band 680-700nm

[0126] That is, light in the wavelength band of 520 to 700 nm is equally divided into nine wavelength bands with a width of 20 nm and intervals of 20 nm. Obtaining such a division into nine is equivalent to obtaining a wavelength dispersion spectrum with a resolution of 20 nm. Below, we will explain how to realize the above basic design.

[0127] First, the bandpass filter BP transmits light in the wavelength band 520 to 700 nm and blocks light of other wavelengths. In particular, it minimizes the transmittance of light with a wavelength of 505 nm, which is the wavelength of the laser beam. Next, the dichroic mirror M1 reflects light in the wavelength band 520 to 600 nm and transmits light in the wavelength band 600 to 700 nm. The dichroic mirrors M2 to M5 equally divide the light in the wavelength band 520 to 600 nm into four wavelength bands with a width of 20 nm and intervals of 20 nm. That is, the dichroic mirror M2 reflects light in the wavelength band 520 to 540 nm and transmits light in the wavelength band 540 to 600 nm. The dichroic mirror M3 reflects light in the wavelength band 540 to 560 nm and transmits light in the wavelength band 560 to 600 nm. The dichroic mirror M4 reflects light in the wavelength range of 560 to 580 nm and transmits light in the wavelength range of 580 to 600 nm. The dichroic mirror M5 reflects light in the wavelength range of 580 to 600 nm.

[0128] Meanwhile, dichroic mirrors M6 to M10 equally divide light in the 600-700 nm wavelength band into five wavelength bands with a width of 20 nm and intervals of 20 nm. That is, dichroic mirror M6 transmits light in the 600-620 nm wavelength band and reflects light in the 620-700 nm wavelength band. Dichroic mirror M7 reflects light in the 620-640 nm wavelength band and transmits light in the 640-700 nm wavelength band. Dichroic mirror M8 reflects light in the 640-660 nm wavelength band and transmits light in the 660-700 nm wavelength band. Dichroic mirror M9 reflects light in the 660-680 nm wavelength band and transmits light in the 680-700 nm wavelength band. Dichroic mirror M10 reflects light in the 680-700 nm wavelength band.

[0129] 14 to 23 show the results of measuring the transmission spectrum of each of the bandpass filters BP and dichroic mirrors M1 to M9 designed based on the above basic design. The transmission spectrum of dichroic mirror M10 is not shown because it has the same spectral characteristics as dichroic mirror M5.

[0130] In the transmission spectrum of each dichroic mirror except for dichroic mirror M5, the cut-on wavelength λC located on the left shoulder of the main transmission band (the region where transmittance increases with wavelength) or the cut-off wavelength λC located on the right shoulder of the main transmission band (the region where transmittance decreases with wavelength) is indicated. If there are multiple cut-on wavelengths λC or cut-off wavelengths λC, select one of them. Here, select the cut-on wavelength λC or cut-off wavelength λC where the transmittance changes more sharply with wavelength, at a transmittance of 50%.

[0131] Figure 14 shows the transmission spectrum of the bandpass filter BP at an incident angle of 0°. The bandpass filter BP transmits light in the wavelength range of 520 to 700 nm. The cut-on wavelength of the bandpass filter BP is λC(BP) = 520 nm, which enables it to strongly block light with a laser beam wavelength of 505 nm.

[0132] 15 shows the transmission spectrum of dichroic mirror M1 at an incident angle of 45°. Dichroic mirror M1 reflects light in the wavelength range of 520 to 600 nm and transmits light in the wavelength range of 600 to 700 nm. The cut-on wavelength of dichroic mirror M1 is λC(M1)=601 nm.

[0133] Figure 16 shows the transmission spectrum of dichroic mirror M2 at an incident angle of 45°. Dichroic mirror M2 reflects light in the wavelength band of 520 to 540 nm and transmits light in the wavelength band of 540 to 600 nm. The cut-on wavelength of dichroic mirror M2 is λC(M2) = 540 nm. There is a transmission band below 520 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0134] Figure 17 shows the transmission spectrum of dichroic mirror M3 at an incident angle of 45°. Dichroic mirror M3 reflects light in the wavelength range of 540 to 560 nm and transmits light in the wavelength range of 560 to 600 nm. The cut-on wavelength of dichroic mirror M3 is λC(M3) = 560 nm. There is a transmission band below 540 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0135] Figure 18 shows the transmission spectrum of dichroic mirror M4 at an incident angle of 45°. Dichroic mirror M4 reflects light in the wavelength range of 560 to 580 nm and transmits light in the wavelength range of 580 to 600 nm. The cut-on wavelength of dichroic mirror M4 is λC(M4) = 580 nm. There is a transmission band below 560 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0136] 19 shows the transmission spectrum of dichroic mirror M5 at an incident angle of 45°. Dichroic mirror M5 reflects light in the wavelength band of 580 to 600 nm, and simultaneously reflects light in the wavelength band of 680 to 700 nm.

[0137] Figure 20 shows the transmission spectrum of dichroic mirror M6 at an incident angle of 45°. Dichroic mirror M6 transmits light in the wavelength range of 600 to 620 nm and reflects light in the wavelength range of 620 to 700 nm. The cutoff wavelength of dichroic mirror M6 is λC(M6) = 620 nm. There is a transmission band above 700 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0138] Figure 21 shows the transmission spectrum of dichroic mirror M7 at an incident angle of 45°. Dichroic mirror M7 reflects light in the wavelength range of 620 to 640 nm and transmits light in the wavelength range of 640 to 700 nm. The cut-on wavelength of dichroic mirror M7 is λC(M7) = 641 nm. There is a transmission band below 620 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0139] Figure 22 shows the transmission spectrum of dichroic mirror M8 at an incident angle of 45°. Dichroic mirror M8 reflects light in the wavelength range of 640 to 660 nm and transmits light in the wavelength range of 660 to 700 nm. The cut-on wavelength of dichroic mirror M8 is λC(M8) = 661 nm. There is a transmission band below 640 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0140] Figure 23 shows the transmission spectrum of dichroic mirror M9 at an incident angle of 45°. Dichroic mirror M9 reflects light in the wavelength range of 660 to 680 nm and transmits light in the wavelength range of 680 to 700 nm. The cut-on wavelength of dichroic mirror M9 is λC(M9) = 681 nm. There is a transmission band below 660 nm that is separate from the main transmission band described above, but this does not pose a problem as long as the above performance is met.

[0141] The above results demonstrate that it is possible to actually manufacture a dichroic mirror array that faithfully follows the basic design described above.

[0142] From the configuration of the dichroic mirror array according to Example 5, the transmission spectrum of the divided light beams C1 to C9 with respect to the incident light beam C0 is calculated as follows using the transmission spectra of the bandpass filter BP and dichroic mirrors M1 to M9 described above: Here, the transmission spectrum of an arbitrary bandpass filter, dichroic mirror, and divided light beam X is represented by [X], and the reflection spectrum of X is represented by (1-[X]). [C1]=[BP]×(1-[M1])×(1-[M2]) …(9) [C2]=[BP]×(1-[M1])×[M2]×(1-[M3]) …(10) [C3]=[BP]×(1-[M1])×[M2]×[M3]×(1-[M4]) …(11) [C4]=[BP]×(1-[M1])×[M2]×[M3]×[M4]×(1-[M5]) …(12) [C5] = [BP] × [M1] × [M6] … (13) [C6]=[BP]×[M1]×(1-[M6])×(1-[M7]) …(14) [C7]=[BP]×[M1]×(1-[M6])×[M7]×(1-[M8]) …(15) [C8]=[BP]×[M1]×(1-[M6])×[M7]×[M8]×(1-[M9]) …(16) [C9]=[BP]×[M1]×(1-[M6])×[M7]×[M8]×[M9]×(1-[M5]) …(17)

[0143] Figure 24 shows the transmission spectra of the split beams C1 to C9 calculated using the results of Figures 14 to 23 and the above formula. These results demonstrate that it is actually possible to manufacture a dichroic mirror array that faithfully follows the basic design described above. Surprisingly, the maximum transmittance of the transmission wavelength bands of the split beams C1 to C9 all exceeds 90%. This shows the ratio when the amount of light of each wavelength in the incident beam C0 is set to 100%. For example, when the amount of light of 610 nm contained in the incident beam C0 is set to 100%, the amount of light of 610 nm contained in the split beam C5 reaches 96%. Such highly efficient spectral performance cannot be obtained even with conventional methods that use, for example, diffraction gratings.

[0144] In the dichroic mirror array according to the fifth embodiment, it is preferable that the following formula (18) is satisfied, which simplifies the configuration of the dichroic mirror array. λC(M2)<λC(M3)<λC(M4)<λC(M1)<λC(M6)<λC(M7)<λC(M8)<λC(M9) …(18)

[0145] Generalizing according to FIG. 1, it is preferable to satisfy any one of the following formulas (19) to (26). λC(DA2)<…<λC(DA(m-1))<λC(DA1)<λC(DB1)<…<λC(DB(n-1)) …(19) λC(DA(m-1))<…<λC(DA2)<λC(DA1)<λC(DB1)<…<λC(DB(n-1)) …(20) λC(DA2)<…<λC(DA(m-1))<λC(DA1)<λC(DB(n-1))<…<λC(DB1) …(21) λC(DA(m-1))<…<λC(DA2)<λC(DA1)<λC(DB(n-1))<…<λC(DB1) …(22) λC(DB1)<…<λC(DB(n-1))<λC(DA1)<λC(DA2)<…<λC(DA(m-1)) …(23) λC(DB(n-1))<…<λC(DB1)<λC(DA1)<λC(DA2)<…<λC(DA(m-1)) …(24) λC(DB1)<…<λC(DB(n-1))<λC(DA1)<λC(DA(m-1))<…<λC(DA2) …(25) λC(DB(n-1))<…<λC(DB1)<λC(DA1)<λC(DA(m-1))<…<λC(DA2) …(26)

[0146] In this way, in the dichroic mirror array of this embodiment, when DA1 to DA(m-1) and DB1 to DB(n-1) are combined into subgroups, it is preferable that each dichroic mirror in the subgroup has a different transmission spectrum at a predetermined incident angle.

[0147] [Example 6] Generally, the intensity of a laser beam, which is excitation light, is several orders of magnitude greater than the intensity of the resulting fluorescence, so in order to measure fluorescence with high sensitivity, a long-pass filter or band-pass filter that blocks light of the laser beam wavelength and transmits fluorescence with longer wavelengths is used. However, when using two types of laser beams, for example, it is difficult to fabricate a long-pass filter or band-pass filter that blocks both laser beams but transmits the multiple types of fluorescence excited by each of them.

[0148] Therefore, it is conceivable to adopt a method using a notch filter that blocks only light of a specific wavelength. Light of the shorter wavelength laser beam wavelength is blocked by a long-pass filter or band-pass filter, and light of the longer wavelength laser beam wavelength is blocked by a notch filter. This method can be used with conventional dichroic mirror arrays or other conventional spectroscopic analysis methods, such as wavelength dispersion using a diffraction grating. However, notch filters are very expensive, making their use impractical.

[0149] In this example, two types of laser beams are used as excitation light sources, and while blocking light of each wavelength, ten colors of fluorescence emitted from phosphors excited by the two laser beams are detected using a dichroic mirror array. The wavelengths of the laser beams are 505 nm and 635 nm.

[0150] 25 is a cross-sectional view showing the configuration of a dichroic mirror array according to Example 6. The dichroic mirror array of this example is mounted on a capillary array DNA sequencer similar to that of Example 4, but differs from Example 4 in that laser beams of two different wavelengths are used as excitation light sources.

[0151] 25, the dichroic mirror array according to this embodiment includes 11 dichroic mirrors M1 to M11, a bandpass filter BP (first filter), and a longpass filter LP (second filter), and divides incident light C0 into 10 beams of divided light C1 to C10. Although not shown in the figure, dichroic mirrors M1 to M6 are group A, and dichroic mirrors M7 to M11 are group B.

[0152] The bandpass filter BP is disposed parallel to the XY plane on the negative Z-axis side of the dichroic mirror M1. The long-pass filter LP is disposed parallel to the YZ plane between the dichroic mirrors M1 and M2.

[0153] The basic design of the dichroic mirror array of this embodiment aims to have each of the split light beams C1 to C10 mainly contain light components in the following wavelength bands, that is, to transmit light in the following wavelength bands relative to the incident light beam C0. The fluorescence measured with the split light beams C1 to C5 is mainly the emission of phosphors excited by a 505 nm laser beam, and the fluorescence measured with the split light beams C6 to C10 is mainly the emission of phosphors excited by a 635 nm laser beam. C1: Wavelength band 520-540nm C2: Wavelength band 540-560nm C3: Wavelength band 560-580nm C4: Wavelength band 580-600nm C5: Wavelength band 600-620nm C6: Wavelength band 650-670nm C7: Wavelength band 670-690nm C8: Wavelength band 690-710nm C9: Wavelength band 710-730nm C10: Wavelength band 730-750nm

[0154] The following describes how to realize the above basic design. First, the bandpass filter BP transmits light in the wavelength range of 520 to 750 nm and blocks light of other wavelengths. In particular, it minimizes the transmittance of light with a wavelength of 505 nm, effectively blocking it. Next, the dichroic mirror M1 transmits light in the wavelength range of 520 to 620 nm and reflects light in the wavelength range of 620 to 750 nm. The dichroic mirrors M7 to M11 equally divide the light in the wavelength range of 520 to 620 nm into five wavelength bands with a width of 20 nm and intervals of 20 nm. That is, the dichroic mirror M7 transmits light in the wavelength range of 520 to 540 nm and reflects light in the wavelength range of 540 to 620 nm. The dichroic mirror M8 reflects light in the wavelength range of 540 to 560 nm and transmits light in the wavelength range of 560 to 620 nm. The dichroic mirror M9 reflects light in the wavelength band of 560 to 580 nm and transmits light in the wavelength band of 580 to 620 nm. The dichroic mirror M10 reflects light in the wavelength band of 580 to 600 nm and transmits light in the wavelength band of 600 to 620 nm. The dichroic mirror M11 reflects light in the wavelength band of 600 to 620 nm.

[0155] Meanwhile, dichroic mirrors M2 to M6 equally divide the light in the 650 to 750 nm wavelength band into five wavelength bands with a width of 20 nm and intervals of 20 nm. First, the long-pass filter LP transmits light in the 650 to 750 nm wavelength band and blocks light of other wavelengths. In particular, it minimizes the transmittance of light with a wavelength of 635 nm, the laser beam, effectively blocking it. Dichroic mirror M2 reflects light in the 650 to 670 nm wavelength band and transmits light in the 670 to 750 nm wavelength band. Dichroic mirror M3 reflects light in the 670 to 690 nm wavelength band and transmits light in the 690 to 750 nm wavelength band. Dichroic mirror M4 reflects light in the 690 to 710 nm wavelength band and transmits light in the 710 to 750 nm wavelength band. The dichroic mirror M5 reflects light in the wavelength range of 710 to 730 nm and transmits light in the wavelength range of 730 to 750 nm. The dichroic mirror M6 reflects light in the wavelength range of 730 to 750 nm.

[0156] As described above, by using laser beams with multiple wavelengths, it is possible to expand applications by exciting a greater variety of fluorophores, and to increase the excitation efficiency of various fluorophores, enabling highly sensitive fluorescence detection.

[0157] [Example 7] Next, an example of application of the dichroic mirror array of the present disclosure to an apparatus that focuses light using a lens, irradiates a reaction cell, and performs spectroscopic analysis of the transmitted light will be described. An example of such an apparatus is an automatic biochemical analyzer. An automatic biochemical analyzer measures various components, such as sugar, cholesterol, protein, and enzymes, using body fluid components such as blood and urine as samples. The various components contained in the sample react with reagents in the reaction cell, changing the absorption spectrum and absorbance of light. By measuring these changes, the various components can be quantified.

[0158] Conventional biochemical analyzers use a diffraction grating to disperse the halogen lamp light that passes through a reaction cell, and then use a photodiode to detect the light intensity at 12 different wavelengths, namely, 340 nm, 405 nm, 450 nm, 480 nm, 505 nm, 546 nm, 570 nm, 600 nm, 660 nm, 700 nm, 750 nm, and 800 nm.

[0159] 26 is a cross-sectional view showing the configuration of a dichroic mirror array according to Example 7. The dichroic mirror array of this example can be applied to, for example, the above-mentioned automatic biochemical analyzer.

[0160] 26, the dichroic mirror array of this embodiment includes 13 dichroic mirrors M1 to M13 and 12 bandpass filters BP1 to BP12 (third filters), and divides incident light C0 into 12 beams of divided light C1 to C12. The divided beams from the dichroic mirror array pass through the bandpass filters BP1 to BP12, respectively, and are incident on the sensor surface S of the sensor as divided beams C1 to C12. Although not shown in the figure, the dichroic mirrors M1 to M7 are group A, and the dichroic mirrors M8 to M13 are group B.

[0161] The basic design of the dichroic mirror array of this embodiment aims to have split lights C1 to C12 with central wavelengths of 340 nm, 405 nm, 450 nm, 480 nm, 505 nm, 546 nm, 570 nm, 600 nm, 660 nm, 700 nm, 750 nm, and 800 nm, respectively, for the incident light C0.

[0162] The following describes how to realize the above basic design. First, dichroic mirror M1 reflects light in the wavelength band of 300 to 560 nm and transmits light in the wavelength band of 560 to 900 nm. Dichroic mirror M2 reflects light in the wavelength band of 300 to 380 nm and transmits light in the wavelength band of 380 to 560 nm. Bandpass filter BP1 transmits light in the wavelength band of 335 to 345 nm. Dichroic mirror M3 reflects light in the wavelength band of 380 to 430 nm and transmits light in the wavelength band of 430 to 560 nm. Bandpass filter BP2 transmits light in the wavelength band of 400 to 410 nm. Dichroic mirror M4 reflects light in the wavelength band of 430 to 470 nm and transmits light in the wavelength band of 470 to 560 nm. Bandpass filter BP3 transmits light in the wavelength band of 445 to 455 nm. Dichroic mirror M5 reflects light in the wavelength band of 470 to 490 nm and transmits light in the wavelength band of 490 to 560 nm. Bandpass filter BP4 transmits light in the wavelength band of 475 to 485 nm. Dichroic mirror M6 reflects light in the wavelength band of 490 to 530 nm and transmits light in the wavelength band of 530 to 560 nm. Bandpass filter BP5 transmits light in the wavelength band of 500 to 510 nm. Dichroic mirror M7 reflects light in the wavelength band of 530 to 560 nm. Bandpass filter BP6 transmits light in the wavelength band of 541 to 551 nm.

[0163] Meanwhile, dichroic mirror M8 transmits light in the wavelength band of 560 to 590 nm and reflects light in the wavelength band of 590 to 900 nm. Furthermore, bandpass filter BP7 transmits light in the wavelength band of 565 to 575 nm. Dichroic mirror M9 reflects light in the wavelength band of 590 to 630 nm and transmits light in the wavelength band of 630 to 900 nm. Furthermore, bandpass filter BP8 transmits light in the wavelength band of 595 to 605 nm. Dichroic mirror M10 reflects light in the wavelength band of 630 to 680 nm and transmits light in the wavelength band of 680 to 900 nm. Furthermore, bandpass filter BP9 transmits light in the wavelength band of 655 to 665 nm. Dichroic mirror M11 reflects light in the wavelength band of 680 to 730 nm and transmits light in the wavelength band of 730 to 900 nm. Furthermore, bandpass filter BP10 transmits light in the 695 to 705 nm range. Dichroic mirror M12 reflects light in the 730 to 780 nm wavelength range and transmits light in the 780 to 900 nm wavelength range. Bandpass filter BP11 transmits light in the 745 to 755 nm range. Dichroic mirror M13 reflects light in the 780 to 900 nm wavelength range. Bandpass filter BP12 transmits light in the 795 to 805 nm range.

[0164] As described above, by replacing conventional spectroscopic analysis with the method of the present disclosure, it is possible to reduce the size of an automatic biochemical analyzer, and also to improve the light utilization efficiency and thereby improve sensitivity.

[0165] 2. Second embodiment Next, a dichroic mirror array according to a second embodiment will be described with reference to Fig. 27. The dichroic mirror array according to this embodiment differs from the first embodiment in that it has three or more groups of dichroic mirrors.

[0166] Figure 27 is a schematic diagram showing the configuration of a multi-color detection device equipped with a 13-segment dichroic mirror array according to the second embodiment. Figure 27(a) is a cross-sectional view of the multi-color detection device in the XZ plane. Figure 27(b) is a view taken along arrow A in Figure 27(a).

[0167] In the example shown in Figure 27, the dichroic mirror array includes dichroic mirrors M1 to M4 in group A, dichroic mirrors M5 to M8 in group B, dichroic mirrors M9 to M12 in group C (third group), and dichroic mirrors M13 to M16 in group D, and splits incident light C0 into 13 beams C1 to C13.

[0168] Groups A to D are arranged in this order along the positive direction of the Z axis, and dichroic mirrors M1, M5, M9, and M13 are all arranged on the Z axis. Dichroic mirrors M1 to M4 are arranged along the positive direction of the X axis. Dichroic mirrors M5 to M8 are arranged along the negative direction of the X axis. Dichroic mirrors M9 to M12 are arranged along the positive direction of the Y axis. Dichroic mirrors M13 to M16 are arranged along the negative direction of the Y axis.

[0169] As described above, the dichroic mirror array according to this embodiment has four groups of dichroic mirrors and a four-layer structure. With the above configuration, the incident light C0 can be divided into 13 beams C1 to C13.

[0170] 27, the multicolor detection device includes a condenser lens L, an area sensor, and a light-emitting point P. The divided light beams C1 to C13 travel in the positive direction of the Z axis, are perpendicularly incident on the sensor surface S of the area sensor, and are detected simultaneously.

[0171] Since the split light beams C1 to C13 are components of different wavelength bands of the incident light beam C0, i.e., components of different colors, it is possible to detect 13 colors of the incident light beam C0 by measuring them simultaneously and independently. In the case of the multi-color detection device shown in Fig. 27, when the maximum optical path length and optical path length difference are evaluated using the unit in the same manner as above, the maximum optical path length is 7 and the optical path length difference is 3. Therefore, it can be seen that by adopting the dichroic mirror array structure shown in Fig. 27, the maximum optical path length and optical path length difference are further reduced compared to the first embodiment and Fig. 3.

[0172] The number of dichroic mirror groups is not limited to four and can be any number. In this case, the dichroic mirrors at the ends of each group are placed at different positions on the Z axis, and the dichroic mirrors belonging to each group are placed at different positions on the XY plane.

[0173] In this embodiment, when the number of groups of dichroic mirrors is generalized, the number of split beams is {total number of dichroic mirrors - (number of groups - 1)}. In contrast, in a conventional dichroic mirror array, the number of split beams is equal to the total number of dichroic mirrors.

[0174] 3. Third embodiment In the first and second embodiments, the thickness of each dichroic mirror is assumed to be negligibly small compared to the width of each dichroic mirror, the arrangement interval, etc., and the dichroic mirrors are arranged flat. However, in reality, as dichroic mirror arrays become smaller, the effect of thickness may become significant. Therefore, in this embodiment, following Patent Document 3, a configuration is adopted in which the dichroic mirrors are arranged in steps.

[0175] Comparative Example 3 A comparative example of the third embodiment will be described below. Fig. 28 is a schematic diagram showing the configuration of a dichroic mirror array according to the third comparative example.

[0176] The dichroic mirror array according to Comparative Example 3 includes dichroic mirrors M1 to M9 and a band-pass filter BP.

[0177] Dichroic mirrors M1 to M9 are nine types of dichroic mirrors arranged in the X-axis direction, but their positions in the Z-axis direction are shifted in the negative direction of the Z-axis in this order. As shown in Figure 28, the incident light and transmitted light of each dichroic mirror M1 to M9 are parallel to each other but their central axes are shifted due to refraction within each dichroic mirror M1 to M9, that is, depending on the thickness of each dichroic mirror M1 to M9. Therefore, by using a stepped arrangement as shown in Figure 28, it is possible to divide the wider incident light C0 into nine, that is, to expand the aperture width.

[0178] In Comparative Example 3, the incident light and the divided light are depicted as beams of light with realistic widths. The beams are represented by 11 infinitesimally spaced rays of light. Each ray depicted in Fig. 28 is the result of ray tracing in accordance with the laws of reflection and refraction.

[0179] Let x be the average spacing of dichroic mirrors M1 to M9 in the X-axis direction, y be the offset of dichroic mirrors M1 and M2 in the Z-axis direction, and z be the average offset of dichroic mirror Mk (2≦k≦8) and dichroic mirror M(k+1) in the Z-axis direction.

[0180] The width of each of the dichroic mirrors M1 to M9 is defined as α, and the thickness as β. Here, the width α is defined as the width of each of the dichroic mirrors M1 to M9 parallel to the XZ plane and perpendicular to the normal vector. The thickness β is defined as the width of each of the dichroic mirrors M1 to M9 parallel to the normal vector.

[0181] The incident angle of the light beam on the incident surface of dichroic mirror M1 is θ0, and the refraction angle on the incident surface is θ1. The incident angle of the light beam on the incident surfaces of dichroic mirrors M2 to M9 is (90°-θ0), and the refraction angle of the light beam on each incident surface is θ2.

[0182] The bandpass filter BP is disposed parallel to the XY plane on the negative Z-axis side of the dichroic mirror M1.

[0183] The area sensor is disposed parallel to the XY plane on the positive Z-axis side of the dichroic mirrors M1 to M9. The divided light beams C1 to C9 are incident perpendicularly on the sensor surface S of the area sensor.

[0184] In Comparative Example 3, incident light C0 is incident on bandpass filter BP at an angle of incidence of 0° in the positive direction of the Z axis and becomes transmitted light traveling in the positive direction of the Z axis. The transmitted light from bandpass filter BP is incident on dichroic mirror M1 at an angle of incidence of 45° and is split into reflected light traveling in the positive direction of the X axis and transmitted light traveling in the positive direction of the Z axis, i.e., divided light C1. The reflected light from dichroic mirror M1 is incident on dichroic mirror M2 at an angle of incidence of 45° and is split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., divided light C2. Subsequently, transmitted light from dichroic mirror Mk (2≦k≦8) is incident on dichroic mirror M(k+1) and is split into transmitted light traveling in the positive direction of the X axis and reflected light traveling in the positive direction of the Z axis, i.e., divided light C(k+1).

[0185] Here, in Comparative Example 3, the width α of the dichroic mirrors M1 to M9 is 3.4 mm, the thickness β is 1.0 mm, the angle θ0 between the incident light on the dichroic mirrors M1 to M9 and the normal line is 45°, the base material of the dichroic mirrors M1 to M9 is quartz glass, and the refractive index n0 is 1.46.

[0186] In this case, Patent Document 3 derives the best mode conditions that result in the shortest maximum optical path length and the widest aperture width. Figure 28 shows an arrangement that satisfies the best mode conditions, and satisfies the following equations (27) to (29). Furthermore, the aperture width V is given by the following equation (30). x=x0=cosθ0*α+sinθ0*β=3.1mm (27) y=y0=cosθ0*β=0.71mm (28) z=z0=sin(90-θ0-θ2) / cosθ2*β=0.32mm (29) V=V0=a V *α+b V *β=2.0mm (30) where a V and b V respectively satisfy the following equations (31) and (32). a V =cosθ0 (31) b V =-cosθ0*tanθ1···(32) Moreover, θ1 and θ2 are given by the following equations (33) and (34). θ1=sin -1 (1 / n0*sinθ0) (33) θ2=sin -1 (1 / n0*sin(90°-θ0)) ···(34)

[0187] In this case, the step between the dichroic mirrors M1 and M9 is as large as 2.9 mm, which means that the maximum optical path length is longer by 2.9 mm compared to when the dichroic mirrors are arranged flat with no misalignment in the Z-axis direction.

[0188] [Example 8] An example of the third embodiment will be described below. Fig. 29 is a schematic diagram showing the configuration of a dichroic mirror array according to an example 8.

[0189] The dichroic mirror array of Example 8 has a configuration similar to that of the dichroic mirror array of Example 5, but differs from Example 5 in that the positions of dichroic mirrors M1 to M5 in the Z-axis direction are shifted in the negative direction of the Z-axis in the stated order, and the positions of dichroic mirrors M6 to M10 in the Z-axis direction are shifted in the negative direction of the Z-axis in the stated order.

[0190] As in Comparative Example 3, let x be the average of the arrangement spacing in the X-axis direction of dichroic mirrors M1 to M5 and the arrangement spacing in the X-axis direction of dichroic mirrors M6 to M10, let y be the average of the Z-axis direction shifts of dichroic mirrors M1 and M2 and dichroic mirrors M6 and M7, and let z be the average of the Z-axis direction shifts of dichroic mirrors Mj (2≦j≦4) and dichroic mirror M(j+1) and dichroic mirror Mk (7≦k≦9) and dichroic mirror M(k+1).

[0191] The width of each of the dichroic mirrors M1 to M10 is defined as α, and the thickness as β. Here, the width α is defined as the width of each of the dichroic mirrors M1 to M10 parallel to the XZ plane and perpendicular to the normal vector. The thickness β is defined as the width of each of the dichroic mirrors M1 to M10 parallel to the normal vector.

[0192] The incident angle of the light beam on the incident surfaces of dichroic mirrors M1 and M6 is θ0, and the refraction angle on these incident surfaces is θ1. The incident angle of the light beam on the incident surfaces of dichroic mirrors M2 to M5 and dichroic mirrors M7 to M10 is (90°-θ0), and the refraction angle of the light beam on each incident surface is θ2.

[0193] In Example 8, too, the conditions for the best mode, in which the maximum optical path length is shortest and the aperture width is widest, can be satisfied by using an optimal step arrangement, following Patent Document 3. As in Comparative Example 3, when α=3.4 mm, β=1.0 mm, θ0=45°, and n0=1.46, according to equations (27) to (30), x0, y0, z0, and V0 each have the same values as in Comparative Example 3.

[0194] In Example 8, the arrangement interval in the X-axis direction of the dichroic mirrors Mj (2≦j≦4) and M(j+1), and the arrangement interval in the X-axis direction of the dichroic mirrors Mk (7≦k≦9) and M(k+1), are respectively x0=3.1 mm. The offset in the Z-axis direction of the dichroic mirrors M1 and M2, and the offset in the Z-axis direction of the dichroic mirrors M6 and M7, are respectively y0=0.71 mm. Furthermore, the offset in the Z-axis direction of the dichroic mirrors Mj and M(j+1), and the offset in the Z-axis direction of the dichroic mirrors Mk and M(k+1), are respectively z0=0.32 mm. The aperture width of the incident light C0 of the dichroic mirror array is V0=2.0 mm.

[0195] In this case, the deviation in the Z-axis direction of the dichroic mirrors M1 and M5 is 1.7 mm, and the deviation in the Z-axis direction of the dichroic mirrors M6 and M10 is also 1.7 mm. In other words, the maximum optical path length is longer by 1.7 mm compared to the case where the dichroic mirrors are arranged flat with no deviation in the Z-axis direction.

[0196] Equations (27) to (30) give the array spacing x0, step height y0, step height z0, and opening width V0 in the best mode, but in reality, the array spacing x, step height y, step height z, and opening width V are effective even if they deviate to some extent from the values in the best mode, as shown in Patent Document 3. Specifically, it is sufficient to satisfy the following equations (35) to (37): cosθ0*α≦x≦cosθ0*α+2*sinθ0*β ···(35) 0≦y≦2*cosθ0*β ···(36) 0≦z≦2*sin(90-θ0-θ2) / cosθ2*β ···(37)

[0197] As described above, the dichroic mirror array of Example 8 has each dichroic mirror arranged in a stepped manner, so that the aperture width can be increased and the optical path length can be reduced.

[0198] 4. Fourth Embodiment 30 is a cross-sectional view showing the configuration of a dichroic mirror array according to the fourth embodiment. In the dichroic mirror arrays shown in the above embodiments, all of the dichroic mirrors form an angle of 45° with respect to the incident light C0, but of course, this is not limited to this.

[0199] The dichroic mirror array of this embodiment comprises dichroic mirrors M1 to M4 in group A, dichroic mirrors M7 to M9 in group B, and dichroic mirrors M5 and M6 arranged between groups A and B, and splits incident light C0 into six beams C1 to C6.

[0200] The dichroic mirrors M1 to M4 are inclined at 45° with respect to the XY and YZ planes and are arranged parallel to one another at approximately equal intervals along the positive direction of the X axis. The dichroic mirrors M7 to M9 are inclined at 45° with respect to the XY and YZ planes and are arranged parallel to one another along the negative direction of the X axis. The normals to the incident surfaces of the dichroic mirrors M1 to M4 in Group A and the dichroic mirrors M7 to M9 in Group B are each parallel to the XZ plane and are arranged in directions perpendicular to one another. The dichroic mirror M2 (corresponding to the above-mentioned DA2) and the dichroic mirror M8 (corresponding to the above-mentioned DB2) are located at different positions in the X axis direction. However, in this embodiment, the positions of the dichroic mirrors in Group A and Group B are the same in the Z axis direction.

[0201] Dichroic mirror M5 is disposed on the positive Z-axis side of dichroic mirror M1, but is tilted at an angle other than 45° with respect to the XY plane and the YZ plane.

[0202] Dichroic mirror M6 is located at the same position in the Z-axis direction as groups A and B, and is disposed between dichroic mirrors M1 and M7. Dichroic mirror M6 is tilted at an angle other than 45° with respect to the XY plane and the YZ plane.

[0203] With this configuration, the light transmitted through dichroic mirror M1 is incident on dichroic mirror M5, the light reflected by dichroic mirror M5 is incident on dichroic mirror M6, and the light reflected by dichroic mirror M6 is incident on dichroic mirror M7.

[0204] 30, the dichroic mirror array of this embodiment can spatially separate the split light beams C1 to C3 from group A and the split light beams C4 to C6 from group B, out of the six split light beams C1 to C6. This makes it possible to detect the split light beams of each group with different sensors. This is effective when all the split light beams cannot fit on a single sensor.

[0205] The present disclosure is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present disclosure, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0206] For example, in the above embodiment, the dichroic mirror array is applied to a capillary array DNA sequencer or an automatic biochemical analyzer, but the present invention is not limited to this and any photodetector can be used. [Explanation of symbols]

[0207] DA1 to DAm: dichroic mirrors in group A, DB1 to DBn: dichroic mirrors in group B, M1 to M16: dichroic mirrors, C0: incident light, C1 to C13: split light, P: light emitting point, L: focusing lens, S: sensor surface, DS: multicolor detection device, 1: laser light source, 2: laser beam, 3: laser beam irradiation position, 4: valve, 5: sample injection port, 6: sample elution port, 7: cathode buffer solution, 8: cathode, 9: anode buffer solution, 10: anode, 11: pump block, 12: syringe, 13: power supply, CA: capillary, BP: bandpass filter, g: light emitting point distance, h: sensor distance, W: spot size, LP: longpass filter

Claims

1. In the right-handed XYZ Cartesian coordinate system, a first group including m (m≧2) dichroic mirrors DA1 to DAm arranged in order parallel to one another along the positive direction of the X axis when viewed from the Z axis; a second group including n (n≧2) dichroic mirrors DB1 to DBn arranged in order parallel to one another along the negative direction of the X axis when viewed from the Z axis; m+n≧6, The X coordinates of the DA2 to DAm are positive, The X coordinates of DB2 to DBn are negative, The incident surfaces of the DA1 to DAm and the incident surfaces of the DB1 to DBn are perpendicular to the XZ plane, The slope of a straight line obtained by projecting a normal to the incident surface of each of the DA1 to DAm onto the XZ plane is negative, The slope of a straight line obtained by projecting a normal to the incident surface of each of the DB1 to DBn onto the XZ plane is positive, The DA1 and the DB1 are disposed adjacent to each other along the positive direction of the Z axis, A dichroic mirror array, wherein the Z coordinate of the DA1 is smaller than the Z coordinate of the DB1.

2. 2. The dichroic mirror array according to claim 1, The normals of the incident surfaces of the DA1 to DAm are parallel to the straight line Z=-X, A dichroic mirror array, wherein the normal to the incident surface of each of the DB1 to DBn is parallel to a straight line Z=X.

3. 2. The dichroic mirror array according to claim 1, The angle between the normal to the incident surface of the dichroic mirror and the Z axis is defined as θ ０ Then, The DA1 to DAm are incident angles θ ０ The transmission spectra at The DB1 to DBn are incident angles θ ０ A dichroic mirror array characterized in that the transmission spectra at different wavelengths are different from each other.

4. 2. The dichroic mirror array according to claim 1, The angle between the normal to the incident surface of the dichroic mirror and the Z axis is defined as θ ０ year, When the DA1 to DA(m-1) and the DB1 to DB(n-1) are subgroups, the dichroic mirrors of the subgroups have an incident angle θ ０ A dichroic mirror array characterized in that the transmission spectra at the respective points are different from each other.

5. 5. The dichroic mirror array according to claim 4, The incident angle θ of the DA1 to DA(m-1) and the DB1 to DB(n-1) ０ The cut-on wavelengths and cut-off wavelengths of the transmission spectrum in the Any one of λ(DA2) to λ(DA(m-1)) is set as λ(DA), If any one of λ(DB1) to λ(DB(n-1)) is λ(DB), then λ(DA)<λ(DA1)<λ(DB), or λ(DA)>λ(DA1)>λ(DB) A dichroic mirror array characterized by satisfying the following.

6. 6. The dichroic mirror array according to claim 5, A dichroic mirror array, wherein the cut-on wavelength or the cut-off wavelength is a wavelength at which the transmittance is approximately 50% and at which the change in transmittance with respect to wavelength is the steepest.

7. 7. The dichroic mirror array according to claim 6, λ(DA2)<λ(DA3)<...<λ(DA(m-1)), or λ(DA2)>λ(DA3)>...>λ(DA(m-1)) A dichroic mirror array characterized by satisfying the following.

8. 7. The dichroic mirror array according to claim 6, λ(DB1)<λ(DB2)<...<λ(DB(n-1)), or λ(DB1)>λ(DB2)>...>λ(DB(n-1)) A dichroic mirror array characterized by satisfying the following.

9. 2. The dichroic mirror array according to claim 1, The Z coordinates of the DA1 to DAm are different from each other, The Z coordinates of DB1 to DBn are different from each other, The DA1 to DAm and the DB1 to DBn, The angle between the normal to the incident surface and the Z axis is θ ０ , The average refractive index of the substrate is n ０ , In a cross section parallel to the XZ plane, the average width of the substrate is defined as α, and the average thickness of the substrate is defined as β, DAj (2≦j≦(m−1)) and DA(j+1), and DBk (2≦k≦(n−1)) and DB(k+1). The average spacing in the X-axis direction is x, If the average arrangement interval in the Z-axis direction is z, then In order to increase the aperture width of the dichroic mirror array or reduce the optical path length, θ ０ , n ０ , α, β, x, and z satisfy a predetermined relationship.

10. 10. The dichroic mirror array according to claim 9, cos (θ) ０ )*α≦+≦2*os(θ ０ )*α+sin(θ ０ )*b A dichroic mirror array characterized by satisfying the following.

11. 10. The dichroic mirror array according to claim 9, θ ２ = sin －１ (1 / n ０ *sin(θ ０ )) then, 0≦z≦2*sin(θ) ０ -θ ２ ) / cos(θ ２ )*b A dichroic mirror array characterized by satisfying the following.

12. 2. The dichroic mirror array according to claim 1, The Z coordinates of the DA1 to DAm are different from each other, The Z coordinates of DB1 to DBn are different from each other, The DA1 to DAm and the DB1 to DBn, The angle between the normal to the incident surface and the Z axis is θ ０ , The average refractive index of the substrate is n ０ , In a cross section parallel to the XZ plane, the average width of the substrate is defined as α, and the average thickness of the substrate is defined as β, of the DA1 and the DA2, and of the DB1 and the DB2 The average spacing in the X-axis direction is x, If the average arrangement interval in the Z-axis direction is y, then In order to increase the aperture width of the dichroic mirror array or reduce the optical path length, θ ０ , n ０ , α, β, x, and y satisfy a predetermined relationship.

13. 13. The dichroic mirror array according to claim 12, cos (θ) ０ )*α≦+≦2*bos(θ ０ )*α+sin(θ ０ )*b A dichroic mirror array characterized by satisfying the following.

14. 13. The dichroic mirror array according to claim 12, 0≦y≦2*cos(θ ０ )*b A dichroic mirror array characterized by satisfying the following.

15. 3. The dichroic mirror array according to claim 2, further comprising a first filter that transmits light in a predetermined wavelength band; the incident surface of the first filter is parallel to the XY plane; the first filter and the DA1 are arranged along the positive direction of the Z axis, A dichroic mirror array, wherein the Z coordinate of the first filter is smaller than the Z coordinate of the DA1.

16. 3. The dichroic mirror array according to claim 2, further comprising a second filter that transmits light in a predetermined wavelength band; the incident surface of the second filter is parallel to the YZ plane; The dichroic mirror array is characterized in that the second filter is disposed between any two adjacent dichroic mirrors of the DA1 to DAm or the DB1 to DBn.

17. 3. The dichroic mirror array according to claim 2, further comprising a third filter that transmits light in a predetermined wavelength band; the incident surface of the third filter is parallel to the XY plane; A dichroic mirror array, wherein the Z coordinate of the third filter is greater than the Z coordinates of the DA1 to DAm and the DB1 to DBn.

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