Prism and light source device

Abstract

Provided are a prism and a light source device with which it is possible to adjust the spacing, shape, and filling rate of beams with a simple structure. The prism has: a first surface including an incidence region into which substantially parallel light is refracted from a collimator that sets a beam from the laser light source as substantially parallel light and enters, and an emission region into which substantially parallel light is refracted and emitted; and a second surface that faces the first surface and includes a reflection region that reflects, toward the emission region, the substantially parallel light that has entered through the incidence region. The beam width of the substantially parallel light incident on the prism in the first direction is larger than the beam width of the substantially parallel light in the second direction orthogonal to the first direction, and the substantially parallel light is arranged at least in the first direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a prism and a light source device. BACKGROUND

[0002] Patent Literature 1 discloses a light source unit. The light source unit of Patent Literature 1 is composed of: a light source group in which a plurality of light sources are arranged in a planar shape in rows and columns; and a first mirror group disposed on an optical axis of the light source group, which reflects light beams emitted from the light sources constituting the light source group as light beams whose cross-sectional areas are reduced in the column direction by narrowing the interval between the rows of the light beams emitted from the light sources constituting the light source group, the first mirror group being composed of different short strip-shaped mirrors disposed in steps on the optical axis of the light beams emitted from the light sources constituting the light source group. The mirrors are disposed so that the reflected light from the mirrors does not have an interval therebetween, whereby the cross-sectional areas of the light beams can be reduced.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2011-13317 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the light source unit of Patent Literature 1, the interval of the beams from the plurality of laser light sources can be narrowed by the mirror group. However, the mirror group has a complicated configuration in which the plurality of mirrors are disposed so that the reflected light from the mirrors does not have an interval therebetween. In order to compose the mirror group, the positions and angles of the plurality of mirrors need to be adjusted, which is complicated and difficult.

[0008] In recent years, laser light sources such as semiconductor lasers of several tens to several hundreds are increasingly used as light sources. The beam of the laser light source is generally elliptical, and it is desired to correct the beam shape to be close to a circular shape. In the light source unit of Patent Literature 1, the interval of the beams can be narrowed, but the beams cannot be made close to a circular shape from an elliptical shape. Therefore, for the light source unit of Patent Literature 1, a deformation optical system such as a deformation lens that makes the aspect ratio different needs to be used, and as a result, a plurality of optical members are required, and the configuration is further complicated.

[0009] The present disclosure provides a prism and a light source device that can adjust the interval, shape, and fill factor of a beam with a simple configuration.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] A prism according to an embodiment of the present disclosure includes a first surface on which a plurality of substantially parallel lights are incident from a plurality of collimators that set a plurality of beams emitted from a plurality of laser light sources as the plurality of substantially parallel lights, and a second surface opposite the first surface. In each of the plurality of substantially parallel lights incident on the prism, a beam width in a first direction is larger than a beam width in a second direction orthogonal to the first direction. The plurality of substantially parallel lights incident on the prism are arranged at least in the first direction. The first surface includes, with respect to each of the plurality of substantially parallel lights, an incident region in which the substantially parallel light is refracted and enters into the prism, and an exit region in which the substantially parallel light is refracted and exits from the prism, and the second surface includes a reflection region that reflects the substantially parallel light that has passed through the incident region and entered into the prism toward the exit region.

[0012] A light source device according to an embodiment of the present disclosure includes a plurality of laser light sources, a plurality of collimators that set a plurality of beams emitted from the plurality of laser light sources as a plurality of substantially parallel lights, and a prism that includes a first surface on which the plurality of substantially parallel lights are incident from the plurality of collimators, and a second surface opposite the first surface. In each of the plurality of substantially parallel lights incident on the prism, a beam width in a first direction is larger than a beam width in a second direction orthogonal to the first direction. The plurality of substantially parallel lights incident on the prism are arranged at least in the first direction. The first surface includes, with respect to each of the plurality of substantially parallel lights, an incident region in which the substantially parallel light is refracted and enters into the prism, and an exit region in which the substantially parallel light is refracted and exits from the prism, and the second surface includes a reflection region that reflects the substantially parallel light that has passed through the incident region and entered into the prism toward the exit region.

[0013] -Effects of Invention-

[0014] An embodiment of the present disclosure provides a prism and a light source device that can adjust the interval, shape, and fill factor of beams with a simple configuration. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view of a light source device according to Embodiment 1.

[0016] Figure 2 is a partial enlarged view of a prism of a light source device according to Embodiment 1.

[0017] Figure 3 is a schematic front view of a light source device according to Embodiment 1.

[0018] Figure 4 is another schematic side view of a light source device according to Embodiment 1.

[0019] Figure 5is a graph showing a change in the angle of the first face of the prism with respect to a change in the refractive index of the prism, which shows a relationship between the angle of the first face of the prism and the rate of change of the first direction of the substantially parallel light related to Embodiment 1.

[0020] Figure 6 is a graph showing a change in the angle of the first face of the prism with respect to a change in the refractive index of the prism, which shows a relationship between the angle of the first face of the prism and the rate of change of the first direction of the substantially parallel light related to Embodiment 1.

[0021] Figure 7 is a graph showing a change in the angle of the first face of the prism with respect to a change in the refractive index of the prism, which shows a relationship between the angle of the first face of the prism and the rate of change of the first direction of the substantially parallel light related to Embodiment 1.

[0022] Figure 8 is a graph showing a change in the angle of the first face of the prism with respect to a change in the refractive index of the prism, which shows a relationship between the angle of the first face of the prism and the rate of change of the first direction of the substantially parallel light related to Embodiment 1.

[0023] Figure 9 is a graph showing the transmittance of the first face of the prism for S-polarized light related to Embodiment 1.

[0024] Figure 10 is an image showing the shape of the substantially parallel light incident on the prism related to Embodiment 1.

[0025] Figure 11 is an image showing the shape of the substantially parallel light emitted from the prism related to Embodiment 1.

[0026] Figure 12 is an image showing the shape of the substantially parallel light reflected by the mirror group related to Embodiment 1.

[0027] Figure 13 is a schematic front view of a light source device related to Embodiment 2.

[0028] Figure 14 is a graph showing the transmittance of the first face of the prism for S-polarized light related to Embodiment 2.

[0029] Figure 15 is a schematic front view of a light source device related to Embodiment 3.

[0030] Figure 16 is a graph showing the transmittance of the first face of the prism for S-polarized light related to Embodiment 3.

[0031] Figure 17 is a schematic front view of a light source device related to Embodiment 4.

[0032] Figure 18 is a schematic front view of a light source device according to Embodiment 5.

[0033] Figure 19 is a graph showing the transmittance of the first surface of a prism according to Embodiment 5 for P-polarized light.

[0034] Figure 20 is a schematic front view of a light source device according to Embodiment 6.

[0035] Figure 21 is a graph showing the transmittance of the first surface of a prism according to Embodiment 6 for S-polarized light.

[0036] Figure 22 is a front view of a portion of a prism according to Embodiment 1.

[0037] Figure 23 is a front view of a portion of a prism according to a modification.

[0038] Figure 24 is a front view of a portion of a prism according to another modification. DETAILED DESCRIPTION

[0039] [1. Embodiment]

[0040] Hereinafter, embodiments will be described in detail with appropriate reference to the accompanying drawings. However, detailed description will be omitted at times where not necessary. For example, detailed description of known matters, repeated description of substantially identical structures will be omitted at times. This is to avoid the following description from becoming unnecessarily lengthy and to make it easier for those skilled in the art to understand. Furthermore, the inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims by the same.

[0041] Unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. The drawings described in the following embodiments are schematic drawings, and the sizes and thicknesses of the respective structural elements in the drawings do not necessarily reflect actual size ratios. In addition, the size ratios of the respective elements are not limited to the ratios illustrated in the drawings.

[0042] Furthermore, in the following description, in cases where it is necessary to distinguish between structural elements that exist in plurality, a prefix of "first", "second", and the like is added to the name of the structural element, but in cases where the structural elements can be distinguished from each other by the symbol added thereto, the prefix of "first", "second", and the like is omitted at times in consideration of readability of the article.

[0043] Further, in the following description, in a case where it is necessary to distinguish between structural elements present in plural, a suffix of "-1", "-2", and the like is added to the symbol of the structural element, but in a case where it is not necessary to distinguish between structural elements present in plural, the suffix of "-1", "-2", and the like is omitted in consideration of legibility of the article.

[0044] [1.1 Embodiment 1]

[0045] [1.1.1 Structure]

[0046] Figure 1 is a schematic view of a light source device 1 to which Embodiment 1 is applied. The light source device 1 is used, for example, for a projector. The light source device 1 is provided with a plurality of laser light sources 2 and an optical system 3.

[0047] The plurality of laser light sources 2 respectively radiate beams B. The beam B is a so-called elliptical beam in which an intensity distribution in a direction away from the laser light source 2, that is, a far-field pattern is elliptical. The laser light source 2 is, for example, a semiconductor laser. In the present embodiment, a long diameter direction, a short diameter direction, and an optical axis direction of each beam B are along an X direction, a Y direction, and a Z direction, respectively. The plurality of laser light sources 2 are arranged in two directions of an X direction corresponding to the long diameter direction of the beam B and a Y direction corresponding to the short diameter direction of the beam B. In the present embodiment, the number of the laser light sources 2 is 24. The 24 laser light sources 2 are arranged in 4 columns X1 to X4 in the X direction and 6 columns Y1 to Y6 in the Y direction.

[0048] The optical system 3 is provided with a plurality of collimators 4, a prism 5, and a mirror group 6.

[0049] The plurality of collimators 4 respectively collimate the plurality of beams B radiated from the plurality of laser light sources 2 as a plurality of substantially parallel lights L. In each of the plurality of substantially parallel lights L incident to the prism 5, a beam width in a first direction is larger than a beam width in a second direction orthogonal to the first direction. The beam width in the first direction or the second direction of the substantially parallel light L can be, for example, 1 / e 2The distance between the 2 points is defined. Furthermore, the beam width of the first direction or the second direction of the substantially parallel light L can also be the full width at half maximum (FWHM). In the present embodiment, the first direction corresponds to the long direction of the beam B, and the second direction corresponds to the short direction of the beam B. Since the plurality of laser light sources 2 are arranged in both the long direction and the short direction of the beam B, the plurality of substantially parallel light L are arranged in both the first direction and the second direction. The collimator 4 can be constituted by an aspherical mirror or a plurality of spherical mirrors, for example. Alternatively, they can be integrated to be in the shape of a lens array. In the present embodiment, the optical system 3 has 24 collimators 4. The 24 collimators 4 are arranged so as to correspond to the 24 laser light sources 2 one-to-one.

[0050] The prism 5 is provided in order to regularize the beam B (substantially parallel light L) and improve the filling rate of the beam B (substantially parallel light L). The prism 5 has a first face 51 on which the plurality of substantially parallel light L from the plurality of collimators 4 is incident, and a second face 52 which opposes the first face 51.

[0051] Figure 2 is an enlarged view of the prism 5. The prism 5 has, on the first face 51, for each of the plurality of substantially parallel light L, an incident region R1 in which the substantially parallel light L is refracted and enters the prism 5, and an exit region R2 in which the substantially parallel light L is refracted and exits the prism 5, and has, on the second face 52, a reflection region R3 which reflects the substantially parallel light L which has entered the prism 5 through the incident region R1 toward the exit region R2.

[0052] Reference will be made to Figure 3 and Figure 4 to further describe the light source device 1, particularly the prism 5. Figure 3 is a schematic front view of the light source device 1, particularly a schematic front view as viewed from the -Y direction. Figure 4 is another schematic side view of the light source device 1, particularly a schematic side view as viewed from the -X direction. Furthermore, in Figure 3 and Figure 4 , the mirror group 6 is omitted.

[0053] The first face 51 is a flat face. The incident region R1 and the exit region R2 are located on the same plane for each of the substantially parallel light L. In the present embodiment, the incident regions R1 of the plurality of substantially parallel light L are located on the same plane as one another, and the exit regions R2 are located on the same plane as one another. The incident region R1 is a portion of the first face 51 on which the substantially parallel light L is incident. The center of the incident region R1 is a position through which the central beam L1 of the substantially parallel light L passes. The size of the incident region R1 can be such that the radiation intensity of the substantially parallel light L becomes 1 / e 2The emission region R2 is a portion of the first face 51 through which the substantially parallel light L is emitted. The center of the emission region R2 is a position through which the central light beam L1 of the substantially parallel light L passes. The size of the emission region R2 can be such that the intensity of the substantially parallel light L becomes 1 / e of the intensity of the substantially parallel light L at the center of the emission region R2 2 The emission region R2 is a portion of the first face 51 through which the substantially parallel light L is emitted. The center of the emission region R2 is a position through which the central light beam L1 of the substantially parallel light L passes. The size of the emission region R2 can be such that the intensity of the substantially parallel light L becomes 1 / e of the intensity of the substantially parallel light L at the center of the emission region R2

[0054] The first face 51 includes the incidence region R1 and the emission region R2 corresponding to each of the plurality of laser light sources 2. In Figure 3 In the case where the laser light sources 2 adjacent to each other in the first direction are assumed to be a first laser light source 2-1 and a second laser light source 2-2, the first face 51 includes a first incidence region R1-1 and a first emission region R2-1 corresponding to the first laser light source 2-1, and a second incidence region R1-2 and a second emission region R2-2 corresponding to the second laser light source 2-2. The first emission region R2-1 is located between the first incidence region R1-1 and the second incidence region R1-2. Thus, in the first face 51, it is possible to reduce the portion in which the emission region R2 overlaps the incidence region R1. Therefore, it is possible to reduce the thermal expansion of the first face 51 locally. In Figure 3 In the case where the laser light sources 2 adjacent to each other in the first direction are assumed to be a first laser light source 2-1 and a second laser light source 2-2, the first face 51 includes a first incidence region R1-1 and a first emission region R2-1 corresponding to the first laser light source 2-1, and a second incidence region R1-2 and a second emission region R2-2 corresponding to the second laser light source 2-2. The first emission region R2-1 is located between the first incidence region R1-1 and the second incidence region R1-2. Thus, in the first face 51, it is possible to reduce the portion in which the emission region R2 overlaps the incidence region R1. Therefore, it is possible to reduce the thermal expansion of the first face 51 locally. In

[0055] Here, the distance on the first face 51 between the centers of the incidence regions R1 (the first incidence region R1-1 and the second incidence region R1-2) of the substantially parallel light L adjacent to each other in the first direction among the plurality of substantially parallel light L is assumed to be s [mm]. The distance on the first face 51 between the midpoint m between the centers of the incidence regions R1 (the first incidence region R1-1 and the second incidence region R1-2) and the emission region R2 (the first emission region R2-1) of the substantially parallel light L adjacent to each other in the first direction is assumed to be t [mm]. The distance s and the distance t vary depending on the refractive index n, the angle a, the angle b, the angle g, and the thickness d [mm] of the prism 5 in the direction of the optical axis of the substantially parallel light L incident on the prism 5. The prism 5 preferably satisfies |2t / s| < 0.3. In particular, it is preferable to satisfy |2t / s| = 0 (i.e., t = 0). Thus, it is possible to cause the substantially parallel light L from the laser light sources 2 adjacent to each other in the first direction to be emitted between the incidence regions R1 of the first face 51 of the prism 5 in such a manner as not to overlap as much as possible. Therefore, it is possible to reduce the region in which the incidence region R1 of the substantially parallel light L overlaps the emission region R2, and it is possible to suppress the influence of the rise in temperature and the change in the refractive index, the change in shape, and the like of the prism 5.

[0056] The second surface 52 is a stepped surface in which multiple parallel first inclined surfaces 52a and multiple parallel second inclined surfaces 52b are arranged alternately when viewed from the second direction (±Y direction) of the approximately parallel light L incident on the first surface 51. Therefore, the multiple first inclined surfaces 52a are not located on the same plane.

[0057] Multiple first inclined surfaces 52a contain reflective regions R3. Multiple second inclined surfaces 52b are surfaces that connect adjacent first inclined surfaces 52a to each other. Second inclined surfaces 52b are not used as reflective regions R3.

[0058] The center of the reflection region R3 is the location through which the central beam L1 of the approximately parallel light L passes. The size of the reflection region R3 can be such that the radiation intensity of the approximately parallel light L is 1 / e of the radiation intensity of the approximately parallel light L at the center of the reflection region R3. 2 The range.

[0059] In this embodiment, the second surface 52 includes four first inclined surfaces 52a-1 to 52a-4. The first inclined surface 52a-1 defines the reflection areas R3 of the six laser light sources 2 in column X1. Similarly, the first inclined surfaces 52a-2 to 52a-4 correspond to columns X2 to X4. In each of columns X1 to X4, the reflection areas R3 are located on the same plane. In each of columns Y1 to Y6, the reflection areas R3 are not located on the same plane.

[0060] In prism 5, the distances between the centers of the plurality of first inclined surfaces 52a and the first surface 51 are equal to each other. Thus, for each of the plurality of approximately parallel light rays L, the distance between the center of the incident region R1 and the center of the reflection region R3 is equal, and the distance between the center of the exit region R3 and the center of the reflection region R1 is equal.

[0061] like Figure 3 As shown, the first surface 51 is inclined relative to the first direction (±X direction) of the generally parallel light L incident on the first surface 51, and the first inclined surface 52a and the second inclined surface 52b are inclined relative to the first direction (±X direction) of the generally parallel light L incident on the first surface 51. Figure 4 As shown, the first surface 51 is parallel to the second direction (±Y direction) of the generally parallel light L incident on the first surface 51 without tilting, and the first tilted surface 52a and the second tilted surface 52b are parallel to the second direction (±Y direction) of the generally parallel light L incident on the first surface 51 without tilting.

[0062] In prism 5, the first face 51 is positioned relative to the first direction (in... Figure 3The angle of the first surface 51 with respect to the second direction (the ±Y direction in FIG. 6) is set to α [°], and the angle of the first inclined surface 52a of the second surface 52 with respect to the first direction is set to β [°]. The angle α is the angle of the incidence region Rl and the exit region R2, and the angle β is the angle of the reflection region R3. The prism 5 satisfies β > α. The angle α is equal to the angle of incidence of the substantially parallel light L with respect to the incidence region Rl.

[0063] In the present embodiment, the first surface 51 is positioned on the right side of the second surface 52 with respect to the side from which the plurality of substantially parallel light L exits the prism 5. Figure 3 In this case, the angles α and β are set to positive in the direction of rotation of the first surface 51 about the rotation axis Al located on the side of the first surface 51 opposite the side from which the plurality of substantially parallel light L exits the prism 5 with respect to the plurality of substantially parallel light L incident on the prism 5. Figure 3 Figure 3 In the present embodiment, the direction of rotation of the first surface 51 about the rotation axis Al located on the side of the first surface 51 opposite the side from which the plurality of substantially parallel light L exits the prism 5 with respect to the plurality of substantially parallel light L incident on the prism 5 is set to positive in the direction of rotation of the second surface 52 about the rotation axis Al located on the left side of the second surface 52. Figure 3 Figure 3 In the present embodiment, the direction of rotation of the first surface 51 about the rotation axis Al located on the side of the first surface 51 opposite the side from which the plurality of substantially parallel light L exits the prism 5 with respect to the plurality of substantially parallel light L incident on the prism 5 is set to positive in the direction of rotation of the second surface 52 about the rotation axis Al located on the left side of the second surface 52. Figure 3 Figure 3 In the present embodiment, the +X direction is set to 0°, and the counterclockwise direction is set to positive. Figure 3 In the present embodiment, the rotation axis Al is illustrated at the end of the first surface 51 on the side of the first surface 51 opposite the side from which the plurality of substantially parallel light L exits the prism 5 with respect to the plurality of substantially parallel light L incident on the prism 5. Figure 3 In the present embodiment, the rotation axis Al is illustrated at the end of the first surface 51 on the side of the first surface 51 opposite the side from which the plurality of substantially parallel light L exits the prism 5 with respect to the plurality of substantially parallel light L incident on the prism 5. Figure 3 In the present embodiment, the angle α is positive in the case where the first surface 51 is rotated in the counterclockwise direction from a position parallel to the first direction, and the angle α is negative in the case where the first surface 51 is rotated in the clockwise direction from a position parallel to the first direction. The same applies to the angle β.

[0064] As shown in FIG. 6, the angle of refraction of the substantially parallel light L with respect to the exit region R2 is set to θ [°]. If the refractive index of the prism 5 is set to n, the prism 5 satisfies the following equation (1). Figure 3 [Equation 1]

[0065]

[0066]

[0067] If the angle of the optical axis of the substantially parallel light L exiting the prism 5 with respect to the optical axis of the substantially parallel light L incident on the prism 5 is set to γ, the following equation (2) is satisfied.

[0068] [Equation 2] ​​​​

[0069]

[0070] As shown Figure 3 in FIG. 1, substantially parallel light L is incident on the incident region R1 of the first surface 51, refracted by the incident region R1 and enters the prism 5, and advances toward the first inclined surface 52a within the prism 5. The substantially parallel light L is reflected by the reflection region R3 of the first inclined surface 52a and advances toward the first surface 51 within the prism 5. The substantially parallel light L is refracted by the emission region R2 of the first surface 51 and is emitted from the emission region R2 to the outside of the prism 5. Thus, the beam width in the first direction of the substantially parallel light L and the interval in the first direction of the plurality of substantially parallel lights L are narrowed.

[0071] Here, the interval in the first direction of the substantially parallel light L incident on the prism 5 is defined as a1, and the beam width in the first direction is defined as b1. In the substantially parallel light L emitted from the prism 5, the interval in the third direction corresponding to the first direction is defined as a2, and the beam width in the third direction is defined as b2. The prism 5 satisfies a2 < a1 and b2 < b1.

[0072] Figure 5 is a graph showing the relationship between the angle α of the first surface 51 of the prism 5 and the change rate in the first direction of the substantially parallel light L with respect to the change in the angle γ. ​​​​​​​​​​​​​​​​​The filling rate of the substantially parallel light L in the first direction is represented by the ratio of the beam width of the substantially parallel light L in the first direction to the distance between the same portions of the substantially parallel light L adjacent in the first direction. If the distance between the same portions of the substantially parallel light L adjacent in the first direction of the substantially parallel light L incident on the prism 5 is set as cl, the filling rate of the substantially parallel light L incident on the prism 5 is represented by bl / cl. Since the distance cl is equal to the interval al, bl / cl = bl / al. If the distance between the same portions of the substantially parallel light L adjacent in the third direction corresponding to the first direction of the substantially parallel light L emitted from the prism 5 is set as c2, the filling rate of the substantially parallel light L emitted from the prism 5 is represented by b2 / c2. Since the distance c2 is equal to the interval a2, b2 / c2 = b2 / a2.

[0077] Figure 6 The filling rate of the substantially parallel light L emitted from the prism 5 is shown in the case where the filling rate of the substantially parallel light L incident on the prism 5 is 50%.

[0078] The higher the filling rate, the more the beam can be concentrated. The fact that the filling rate of the substantially parallel light L emitted from the prism 5 is higher than the filling rate of the substantially parallel light L incident on the prism 5 means that the beam can be concentrated more. In the case where the filling rate of the substantially parallel light L incident on the prism 5 is 50%, the filling rate of the substantially parallel light L emitted from the prism 5 is 100% in the example shown in FIG. 6. Figure 6 In the case where the filling rate of the substantially parallel light L incident on the prism 5 is 50%, the filling rate of the substantially parallel light L emitted from the prism 5 is 100% in the example shown in FIG. 6. Figure 6 If the filling rate of the substantially parallel light L emitted from the prism 5 exceeds 50%, the filling rate is improved, that is, means that the beam can be concentrated more.

[0079] Therefore, the prism 5 is set to satisfy the following equation (3).

[0080] [Mathematical equation 3]

[0081]

[0082] That is, in the prism 5, the filling rate of the substantially parallel light L emitted from the prism 5 is greater than the filling rate of the substantially parallel light L incident on the prism 5.

[0083] According to the above Figure 6 , in order to improve the filling rate after emission, it is desirable to reduce the angle a or increase the angle g. In addition, it should be understood that in the case where the angle g is lower than 90°, it is advantageous to set the angle a to be negative.

[0084] If the variation rate of the substantially parallel light L in the first direction and the filling rate are considered, the prism 5 preferably satisfies the following equation (4).

[0085] [Mathematical equation 4]

[0086]

[0087] In the case of α ≤ γ - 90, the substantially parallel light L reflected by the reflection region R3 can be totally reflected by the exit region R2 of the 1st surface 51. In the case of α ≥ γ / 2, the rate of change can be 100% or more.

[0088] Generally, the ellipticity (ratio of the beam width in the short direction to the beam width in the long direction) of a semiconductor laser is about 0.2 to 0.5 or so. Therefore, in order to make the ellipticity close to 1, the prism 5 preferably satisfies the following equations (5) and (6).

[0089] [Equation 5]

[0090]

[0091] [Equation 6]

[0092]

[0093] In the case of γ ≤ 50, since the substantially parallel light L exiting from the exit region R2 approaches the laser light source 2 side, it can be difficult to configure the optical system 3. In the case of γ ≥ 100, the possibility of total reflection of the substantially parallel light L in the exit region R2 is high, and in addition, a useless space can be generated in the optical system 3. In the case of α ≤ 1.1 γ - 90, the effect of compression of the beam width in the 1st direction of the substantially parallel light L is reduced, and in the case of α ≥ 0.95 γ - 60, the effect of compression in the 1st direction of the substantially parallel light L is too large, and the shape of the substantially parallel light L can not be a circular shape but an elliptical shape in which the beam width in the 1st direction is smaller than the beam width in the 2nd direction.

[0094] Figure 7 is a graph showing the change in the refractive index n with respect to the relationship between the angle α of the 1st surface 51 of the prism 5 and the rate of change in the 1st direction of the substantially parallel light L.

[0095] Figure 7 In the case of an angle γ of 60° and in the case of an angle γ of 90°, the refractive index n is changed to 1.4, 1.5, 1.7. According to Figure 7 It can be understood that the relationship between the angle α and the rate of change is less dependent on the refractive index n of the prism 5.

[0096] Figure 8 is a graph showing the change in the refractive index n with respect to the relationship between the angle α of the 1st surface 51 of the prism 5 and the fill rate in the 1st direction of the substantially parallel light L.

[0097] Figure 8 In the case of an angle γ of 60° and in the case of an angle γ of 90°, the refractive index n is changed to 1.4, 1.5, 1.7. Figure 8The fill factor of the substantially parallel light L emitted from the prism 5 is 50%.

[0098] According to Figure 8 It is understood that, in order to increase the fill factor to 50% or more, it is effective to reduce the refractive index n of the prism 5. In addition, it is understood that, in order to obtain the highest fill factor by selecting the angle a, it is more effective to increase the angle y.

[0099] One example of the parameters of the light source device 1 according to the present embodiment is shown in Table 1 below.

[0100] [Table 1]

[0101]

[0102] The prism 5 compresses the beam width of the first direction of the substantially parallel light L. In the substantially parallel light L, the beam width of the first direction is larger than the beam width of the second direction. Therefore, by compressing the beam width of the first direction of the substantially parallel light, the substantially parallel light L approaches a circular shape from an elliptical shape. In addition, the prism 5 can increase the fill factor of the first direction of the substantially parallel light L.

[0103] In consideration of the light utilization efficiency of the prism 5, an antireflection film is formed on the first face 51. In the case where the laser light source 2 is a general semiconductor laser, the beam B is linearly polarized light. Since the first face 51 includes the incidence region Rl and the emission region R2, if the transmittance of the incidence region Rl to a given linearly polarized light is T α , the transmittance of the emission region R2 to the given linearly polarized light is T θ , it is preferable to form the antireflection film on the first face 51 so as to satisfy the following equation (7). In the present embodiment, the beam B is S-polarized light in the long diameter direction and P-polarized light in the short diameter direction. In the present embodiment, the first direction of the substantially parallel light L corresponds to the long diameter direction of the beam B. Therefore, in the first direction of the substantially parallel light L, the transmittance to S-polarized light is considered. That is, the given linearly polarized light is S-polarized light.

[0104] [Equation 7]

[0105]

[0106] Figure 9 is a graph showing the transmittance of the first face 51 of the prism 5 to S-polarized light. G11, G12 correspond to the antireflection film of the first example. G21, G22 correspond to the antireflection film of the second example. G11, G21 show the transmittance T αRelative to the change in wavelength, G12 and G22 represent the transmittance T of the emission region R2 for S-polarized light. θ The transmittance T of incident region R1 for S-polarized light is relative to the wavelength. α This represents the transmittance of light incident at angle α onto surface 51. The transmittance T of the exit region R2 for S-polarized light is also shown. θ This represents the transmittance of light incident on the first surface 51 at an angle equal to the angle of refraction θ.

[0107] The reference wavelength for prism 5 and the antireflective films in Examples 1 and 2 is 450 nm. Prism 5 is made of glass with a refractive index of 1.52532 relative to the reference wavelength. The antireflective film in Example 1 is a conventionally known single-layer film of MgF2 with a thickness of 1 / 4 of the reference wavelength. The antireflective film in Example 2 is a multilayer film obtained by alternately stacking layers made of materials with different refractive indices relative to the reference wavelength. The structure of the antireflective film in Example 2 is shown in Table 2 below.

[0108] [Table 2]

[0109]

[0110] According to G11 and G12, in the antireflective film of the first example, the transmittance T of the incident region R1 for S-polarized light is... α It covers a wide wavelength range of over 98%, but the transmittance T of the emission region R2 for S-polarized light is... θ The transmittance is below 12% across a wide wavelength range. Therefore, the transmittance is low for conventional single-layer coatings. Thus, improving transmittance is desired.

[0111] According to G21 and G22, in the antireflective film of the second example, the transmittance T near the reference wavelength is... α T θ All are relatively high, within the range of W11 to W12, T α ·T θ ≥90%. W11 is 437nm, and W12 is 467nm. Therefore, if it is the antireflective film of the second example, then even the first surface 51 of the double-transmission prism 5 can ensure the total transmittance (=T) within the range that can fully cover the wavelength deviation of a semiconductor laser with a wavelength range of 30nm. α ·T θ It has a high transmittance of over 90%.

[0112] In this way, by using a single prism 5, the approximately parallel light L can be made to approach a perfect circle from an elliptical shape, the spacing of the approximately parallel light L in the first direction can be narrowed, and the filling rate of the approximately parallel light L can be improved. Therefore, the optical system 3 can be made more compact.

[0113] The mirror group 6 is provided in order to increase the fill factor of the substantially parallel light L. The mirror group 6 includes a plurality of mirrors 6a-1 to 6a-6 that reflect the plurality of substantially parallel light L emitted from the prism 5. The plurality of mirrors 6a-1 to 6a-6 are arranged such that the interval of the second direction of the plurality of substantially parallel light L reflected by the mirror group 6 is smaller than the interval of the second direction of the plurality of substantially parallel light L before being reflected by the mirror group 6.

[0114] [1.1.2 Evaluation, etc.]

[0115] In order to confirm the effect of the light source device 1 according to the present embodiment, the shape of the substantially parallel light L was evaluated.

[0116] Figure 10 is an image showing the shape of the substantially parallel light L incident on the prism 5 from the collimator 4. Figure 11 is an image showing the shape of the substantially parallel light L emitted from the prism 5. Figure 12 is an image showing the shape of the substantially parallel light L reflected by the mirror group 6. In Figure 10 to Figure 12 , the whiter the color, the higher the radiation intensity is represented. Figure 10 to Figure 12 X1 to X4 and Y1 to Y6 of Figure 1 correspond to X1 to X4 and Y1 to Y6 of

[0117] From Figure 10 it can be understood that, after the substantially parallel light L is emitted from the collimator 4, before being incident on the prism 5, the beam width of the first direction (the ±X direction in Figure 10 ) is larger than the beam width of the second direction (the ±Y direction in Figure 10 ), and the substantially parallel light L is in an elliptical shape.

[0118] From Figure 11 it can be understood that, after the substantially parallel light L is emitted from the prism 5, before being incident on the mirror group 6, the beam width of the first direction (the ±Z direction in Figure 11 ) and the beam width of the second direction (the ±Y direction in Figure 11 ) are reduced to the same extent, and the substantially parallel light L is closer to a circular shape than the elliptical shape. Further, the interval of the first direction of the substantially parallel light L is narrowed.

[0119] From Figure 12 it can be understood that, after being emitted from the mirror group 6, the interval of the second direction (the ±X direction in Figure 12 ) of the substantially parallel light L is narrowed.

[0120] In the light source device 1 described above, the interval of the substantially parallel light L is narrow in both the first direction and the second direction, and the shape of the substantially parallel light L approaches a circular shape from an elliptical shape, and as a result, it is confirmed that the concentration of the beam is improved.

[0121] [1.1.3 Effects and the like]

[0122] The prism 5 described above has a first face 51 on which a plurality of substantially parallel light Ls are incident from a plurality of collimators 4 that set a plurality of beams B emitted from a plurality of laser light sources 2 as the plurality of substantially parallel light Ls, and a second face 52 that opposes the first face 51. In each of the plurality of substantially parallel light Ls that are incident to the prism 5, the beam width in the first direction is greater than the beam width in the second direction that is orthogonal to the first direction. The plurality of substantially parallel light Ls that are incident to the prism 5 are arranged at least in the first direction. The first face 51 includes, for each of the plurality of substantially parallel light Ls, an incident region R1 in which the substantially parallel light L is refracted and enters into the prism 5, and an exit region R2 in which the substantially parallel light L is refracted and exits from the prism 5, and the second face 52 includes a reflection region R3 that reflects the substantially parallel light L that has entered the prism 5 through the incident region R1 toward the exit region R2. This structure enables adjustment of the interval, the shape, and the fill factor of the beam with a simple configuration.

[0123] In the prism 5, if an angle of the incident region R1 and the exit region R2 with respect to the first direction is set as a [°], and an angle of the reflection region R3 with respect to the first direction is set as β [°], β > a is satisfied. This structure enables narrowing of the interval of the beam (substantially parallel light L) with a simple configuration, and further enables improvement of the circularization and the fill factor of the beam (substantially parallel light L).

[0124] In the prism 5, if an interval of the first direction of the plurality of substantially parallel light Ls that are incident to the prism 5 is set as a1, a beam width of the first direction is set as b1, an interval of a third direction that corresponds to the first direction among the plurality of substantially parallel light Ls that exit from the prism 5 is set as a2, and a beam width of the third direction is set as b2, b2 / a2 > b1 / a1 is satisfied. This structure enables not only compression of the interval of the beam in the first direction, but also improvement of the fill factor of the beam.

[0125] In the prism 5, if a refractive index of the prism 5 is set as n, and a refractive angle of the plurality of substantially parallel light Ls with respect to the exit region R2 is set as θ [°], θ = sin -1 (n · sin (sin -1 (sin a / n) + 2 (β - a)) is satisfied. If a transmittance of the incident region R1 with respect to a given straight line (S polarized light) is set as T α [%], and a transmittance of the exit region R2 with respect to the given straight line (S polarized light) is set as T θ[%], then T α • T θ ≥ 90%. This structure can achieve high transmittance even in the case where the refraction at 2 different angles in the incident region R1 and the emission region R2 exists.

[0126] In the prism 5, the incident region R1 and the emission region R2 are located on the same plane in the first direction. This structure can simplify the configuration of the prism 5.

[0127] In the prism 5, the reflection region R2 is arranged not to be located on the same plane in the first direction. This structure can thin the prism 5.

[0128] In the prism 5, for each of the plurality of substantially parallel light L, the distance between the center of the incident region R1 and the center of the reflection region R3 is equal, and the distance between the center of the emission region R2 and the center of the reflection region R3 is equal. This structure can thin the prism 5.

[0129] In the prism 5, if the distance on the first face 51 between the centers of the incident regions R1 of the substantially parallel light L adjacent in the first direction among the plurality of substantially parallel light L is set as s [mm], and the distance on the first face 51 between the midpoint m between the centers and the emission region R2 of the substantially parallel light L adjacent to the midpoint m among the emission regions R2 is set as t [mm], then |2t / s| < 0.3 is satisfied. This structure can reduce the portion where the incident region R1 and the emission region R2 overlap, and can reduce the thermal expansion of the local portion of the first face 51.

[0130] In the prism 5, if the angle of the optical axis of the plurality of substantially parallel light L emitted from the prism 5 with respect to the optical axis of the plurality of substantially parallel light L incident to the prism 5 is set as γ [°], then γ - 90 < α < γ / 2 is satisfied. This structure can improve the reduction ratio and the fill factor of the first direction of the substantially parallel light L.

[0131] In the prism 5, further, 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60 are satisfied. This structure can further improve the reduction ratio and the fill factor of the first direction of the substantially parallel light L.

[0132] The light source device 1 described above is provided with: a plurality of laser light sources 2; a plurality of collimators 4 that set a plurality of beams B emitted from the plurality of laser light sources 2 as a plurality of substantially parallel light L; and a prism 5 that has a first face 51 on which the plurality of substantially parallel light L is incident from the plurality of collimators 4 and a second face 52 that opposes the first face 51. In each of the plurality of substantially parallel light L that is incident to the prism 5, a beam width in a first direction is larger than a beam width in a second direction that is orthogonal to the first direction. The plurality of substantially parallel light L is arranged at least in the first direction. The first face 51 includes, for each of the plurality of substantially parallel light L, an incident region R1 in which the substantially parallel light L is refracted and enters the prism 5, and an exit region R2 in which the substantially parallel light L is refracted and exits from the prism 5, and the second face 52 includes a reflection region R3 that reflects the substantially parallel light L that has passed through the incident region R1 and entered the prism 5 toward the exit region R2. This structure enables adjustment of the interval, shape, and fill factor of the beams with a simple configuration.

[0133] In the light source device 1, the plurality of substantially parallel light L that is incident to the prism 5 is arranged in both the first direction and the second direction. This structure configures the laser light sources 2 on a plane, and thus enables high output.

[0134] The light source device 1 is further provided with: a mirror group 6 that reflects the plurality of substantially parallel light L that exits from the prism 5. The mirror group 6 includes a plurality of mirrors 6a that are arranged such that the interval of the second direction of the plurality of substantially parallel light L after being reflected by the mirror group 6 is smaller than the interval of the second direction of the plurality of substantially parallel light L before being reflected by the mirror group 6. This structure also enables compression of the interval of the beams in the second direction.

[0135] [1.2 Embodiment 2]

[0136] [1.2.1 Configuration]

[0137] Figure 13 is a schematic side view of the light source device 1A according to Embodiment 2, particularly a schematic side view as viewed from the -Y direction. The light source device 1A is provided with a plurality of laser light sources 2 and an optical system 3A. The optical system 3A is provided with a plurality of collimators 4 and a prism 5A.

[0138] The prism 5A has a first face 51 and a second face 52 similarly to the prism 5, but mainly differs from the prism 5 in the refractive index n, the angle a, the angle b, the angle g, and the thickness d.

[0139] One example of the parameters of the light source device 1A according to this embodiment is shown in Table 3 below.

[0140] [Table 3]

[0141]

[0142] As understood from the comparison between Table 1 and Table 3, by reducing the refractive index of the prism, the fill factor can be increased.

[0143] Figure 14 is a graph showing the transmittance of the first face 51 of the prism 5A with respect to S-polarized light. G31 indicates the transmittance T α with respect to the change in wavelength. G32 indicates the transmittance T θ with respect to the change in wavelength. The transmittance T α indicates the transmittance with respect to light incident on the first face 51 at an angle a (= 5°). The transmittance T θ indicates the transmittance with respect to light incident on the first face 51 at an angle equal to the refractive angle θ (= 80°).

[0144] The reference wavelength of the prism 5A and the antireflection film is 450 nm. The material of the prism 5A is glass, and the refractive index with respect to the wavelength of the reference wavelength is 1.4391. The antireflection film of the prism 5A is a multilayer film obtained by alternately laminating layers composed of materials having different refractive indices with respect to the reference wavelength. The structure of the antireflection film is shown in Table 4 below.

[0145] [Table 4]

[0146]

[0147] According to G41 and G42, in the antireflection film of the structure of Table 4, T α · T θ ≥ 90% in the wavelength range of W21 to W22 including the reference wavelength. W21 is 442 nm, and W22 is 460 nm. Therefore, if the antireflection film of the structure of Table 4, even if the first face 51 of the prism 5A is transmitted twice, it is possible to ensure a high transmittance of 90% or more in the total transmittance (= T α · T θ ) in a range capable of sufficiently covering the deviation of the wavelength of the semiconductor laser of 18 nm.

[0148] In this way, the prism 5A can adjust the interval, the shape, and the fill factor of the beams. In particular, by one prism 5A, it is possible to make the substantially parallel light L approach a circular shape from an elliptical shape, to narrow the interval of the first direction of the substantially parallel light L, and to increase the fill factor of the substantially parallel light L. Therefore, it is possible to make the optical system more compact.

[0149] [1.2.2 Effects and the like]

[0150] The prism 5A described above satisfies β > a. This structure can narrow the interval of the beams (substantially parallel light L) with a simple configuration, and further, can increase the circularization and the fill factor of the beams (substantially parallel light L).

[0151] Prism 5A satisfies b2 / a2>b1 / a1. This structure not only compresses the beam spacing in the first direction but also increases the beam fill rate.

[0152] Prism 5A satisfies θ = sin -1 (n·sin(sin)) -1 (sinα / n)+2(β-α)), and satisfy T α ·T θ ≥90%. This structure can achieve high transmittance even when there are two different angles of refraction in the incident region R1 and the exit region R2.

[0153] Prism 5A satisfies γ-90<α<γ / 2. This structure can improve the reduction ratio and fill ratio in the first direction of the approximately parallel light L.

[0154] Prism 5A further satisfies 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60. This structure enables further improvement in the reduction ratio and fill ratio of the approximately parallel light L in the first direction.

[0155] [1.3 Implementation Method 3]

[0156] [1.3.1 Structure]

[0157] Figure 15 This is a schematic side view of the light source device 1B according to Embodiment 3, particularly a schematic side view viewed from the -Y direction. The light source device 1B includes multiple laser light sources 2 and an optical system 3B. The optical system 3B includes multiple collimators 4 and prisms 5B.

[0158] Prism 5B has the same first face 51 and second face 52 as prism 5, but mainly differs from prism 5 in refractive index n, angle α, angle β, angle γ and thickness d.

[0159] Table 5 below shows an example of the parameters of the light source device 1B according to this embodiment.

[0160] [Table 5]

[0161]

[0162] Comparing Tables 1 and 5, by increasing the refractive index of the prism, the apex angle of prism 5B, defined by the difference between angles α and β, becomes smaller. Therefore, since the second face 52 of prism 5B is close to a plane, shape accuracy can be easily achieved when manufacturing prism 5B using methods such as glass forming.

[0163] Figure 16is a graph showing the transmittance of the first face 51 of the prism 5B with respect to S-polarized light. G41 indicates the transmittance T α with respect to the wavelength. G42 indicates the transmittance T θ with respect to the wavelength. The transmittance T α indicates the transmittance with respect to light incident on the first face 51 at an angle a (= 25°). The transmittance T θ indicates the transmittance with respect to light incident on the first face 51 at an angle equal to the refractive angle θ (= 65°).

[0164] The reference wavelength of the prism 5B and the antireflection film is 500 nm. The material of the prism 5B is glass, and the refractive index with respect to the wavelength of the reference wavelength is 1.62904. The antireflection film of the prism 5B is a multilayer film obtained by alternately laminating layers composed of materials having different refractive indices with respect to the reference wavelength. The structure of the antireflection film is shown in Table 6 below.

[0165] [Table 6]

[0166]

[0167] According to G41 and G42, in the antireflection film of the structure of Table 6, the transmittance T α · T θ is 90% or more in the wavelength range of W31 to W32 including the reference wavelength. W31 is 487 nm, and W32 is 656 nm. Therefore, if the antireflection film of the structure of Table 6, it is possible to ensure a high transmittance in which the total transmittance (= T α · T θ ) is 90% or more even if the first face 51 of the prism 5B is transmitted twice in a very wide range in which the wavelength range is about 170 nm. Therefore, for example, even in the case of using a semiconductor laser of two wavelength bands of green and red, it is possible to make the transmittance of both by only the antireflection film of the structure of Table 6. In addition, the antireflection film of the structure of Table 6 is different from the antireflection film of the structure of Table 2 or Table 4b, and can be implemented using a simple structure of two layers.

[0168] In this way, the prism 5B can adjust the interval, the shape, and the fill factor of the beams. In particular, by one prism 5B, it is possible to make the substantially parallel light L approach a circular shape from an elliptical shape, to narrow the interval of the first direction of the substantially parallel light L, and to increase the fill factor of the substantially parallel light L. Therefore, it is possible to make the optical system more compact.

[0169] [1.3.2 Effects and the like]

[0170] The prism 5B satisfies β > α. This structure can narrow the interval of the beams (substantially parallel light L) with a simple configuration, and further, can increase the circularity and filling rate of the beams (substantially parallel light L).

[0171] The prism 5B satisfies b2 / a2 > b1 / a1. This structure can not only compress the interval of the beams in the first direction, but also increase the filling rate of the beams.

[0172] The prism 5B satisfies θ = sin -1 (n • sin (sin -1 (sina / n) + 2(β - α)), and satisfies T α • T θ ≥ 90%. This structure can achieve a high transmittance even in the case where there is refraction at different angles of the second order in the incidence region R1 and the emission region R2.

[0173] The prism 5B satisfies γ - 90 < α < γ / 2. This structure can increase the reduction rate and filling rate of the first direction of the substantially parallel light L.

[0174] The prism 5B further satisfies 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60. This structure can further increase the reduction rate and filling rate of the first direction of the substantially parallel light L.

[0175] [1.4 Embodiment 4]

[0176] [1.4.1 Structure]

[0177] Figure 17 is a schematic side view of the light source device 1C according to Embodiment 4, particularly a schematic side view as viewed from the -Y direction. The light source device 1C includes a plurality of laser light sources 2 and an optical system 3C. The optical system 3C includes a plurality of collimators 4 and a prism 5C.

[0178] The prism 5B has a first face 51 and a second face 52 like the prism 5, but differs from the prism 5 mainly in the refractive index n, the angle α, the angle β, the angle γ, and the thickness d.

[0179] In this embodiment, the first face 51 is oriented toward the side opposite to the side from which the plurality of substantially parallel light L is emitted from the prism 5 (the right side of the Figure 17 ) with respect to the plurality of substantially parallel light L incident to the prism 5. In this case, the angles α and β rotate the first face 51 about the side (the left side of the Figure 17 ) opposite to the side from which the plurality of substantially parallel light L is emitted from the prism 5 (the right side of the Figure 17 ) with respect to the plurality of substantially parallel light L incident to the prism 5, along the second direction (the -Y direction in Figure 17The rotation axis A1 (within the ±Y direction) is away from the rotation direction of the second surface 52 (in the ±Y direction). Figure 17 (The center is in a clockwise direction) is set to positive. That is to say, in Figure 17 In this configuration, the -X direction is set to 0°, and the clockwise direction is set to positive. Furthermore, in... Figure 17 In the diagram, the rotation axis A1 is shown on the side relative to the plurality of generally parallel light rays L incident on the prism 5 and the plurality of generally parallel light rays L exiting from the prism 5. Figure 17 The opposite side (right side) Figure 17 The end of the first face 51 (left side).

[0180] Table 7 below shows an example of the parameters of the light source device 1C involved in this embodiment.

[0181] [Table 7]

[0182]

[0183] Thus, even if the first surface 51 is not directed relative to the plurality of approximately parallel light rays L incident on the prism 5 but towards the side from which the plurality of approximately parallel light rays L exit the prism 5 ( Figure 17 Instead of the right side, the approximately parallel light L is directed towards the opposite side, allowing it to penetrate the incident region R1 and enter the prism 5C. A comparison of Tables 1 and 7 reveals that when the first surface 51 is directed towards the side opposite to the side from which the approximately parallel light L exits the prism 5, the fill rate is very high. Specifically, the fill rate of the approximately parallel light L exiting the prism 5C is 84.1%, which is very high, relative to the 50.0% fill rate of the approximately parallel light L incident on the prism 5C. This allows the prism 5C to significantly improve the beam concentration, focusing the beam into a narrower area. This makes the optical system 3C more compact. Furthermore, in this embodiment, even when... Figure 17 With the +X direction set to 0° and the counterclockwise direction set to positive, angle α = -20.000 and angle β = 6.604. In this case, β > α is also satisfied. Based on this, it can also be said that a negative angle α means that the first surface 51 is oriented towards the opposite side from the side from which the multiple approximately parallel light rays L are emitted from the prism 5, relative to the multiple approximately parallel light rays L incident on the prism 5.

[0184] In this way, prism 5C can adjust the beam spacing, shape, and fill rate. In particular, by using a single prism 5C, the approximately parallel beam L can be made to move from an elliptical shape to a near-circular shape, the spacing of the approximately parallel beam L in the first direction can be narrowed, and the fill rate of the approximately parallel beam L can be increased. Therefore, the optical system can be made more compact.

[0185] [1.4.2 Effects, etc.]

[0186] The prism 5C satisfies β > α. This structure can narrow the interval of the beams (substantially parallel light L) with a simple configuration, and further, can increase the circularity and the fill factor of the beams (substantially parallel light L).

[0187] The prism 5C satisfies b2 / a2 > b1 / a1. This structure can not only reduce the interval of the beams in the first direction, but also increase the fill factor of the beams.

[0188] The prism 5C satisfies θ = sin -1 (n • sin (sin -1 (sina / n) + 2(β - α)), and satisfies T α • T θ ≥ 90%. This structure can achieve a high transmittance even in the case where there is refraction at two different angles in the incidence region R1 and the emission region R2.

[0189] The prism 5C satisfies γ - 90 < α < γ / 2. This structure can increase the reduction ratio and the fill factor of the beams (substantially parallel light L) in the first direction.

[0190] The prism 5C further satisfies 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60. This structure can further increase the reduction ratio and the fill factor of the beams (substantially parallel light L) in the first direction.

[0191] [1.5 Embodiment 5]

[0192] [1.5.1 Structure]

[0193] Figure 18 is a schematic side view of a light source device 1D related to Embodiment 5, particularly a schematic side view as viewed from the -Y direction. The light source device 1D is provided with a plurality of laser light sources 2 and an optical system 3D. The optical system 3D is provided with a plurality of collimators 4 and a prism 5D.

[0194] The prism 5D has a first face 51 and a second face 52 like the prism 5, but mainly differs from the prism 5 in the refractive index n, the angle α, the angle β, the angle γ, and the thickness d.

[0195] One example of parameters of the light source device 1D related to this embodiment is shown in Table 8 below.

[0196] [Table 8]

[0197]

[0198] The prism 5D compresses the beam width of the first direction of the substantially parallel light L. In the substantially parallel light L, the beam width of the first direction is larger than the beam width of the second direction. Therefore, by compressing the beam width of the first direction of the substantially parallel light, the substantially parallel light L approaches a circular shape from an elliptical shape. In addition, the prism 5D can increase the fill factor of the first direction of the substantially parallel light L.

[0199] In consideration of the light use efficiency of the prism 5D, an antireflection film is formed on the first face 51. In the case where the laser light source 2 is a general semiconductor laser, the beam B is linearly polarized light. If the transmittance of the incident region Rl to a given linearly polarized light is T α , the transmittance of the emission region R2 to a given linearly polarized light is T θ , it is preferable to form the antireflection film on the first face 51 so as to satisfy the above formula (7). In the present embodiment, the beam B is P-polarized light in the long diameter direction and S-polarized light in the short diameter direction. In the present embodiment, the first direction of the substantially parallel light L corresponds to the long diameter direction of the beam B. Therefore, in the first direction of the substantially parallel light L, the transmittance to P-polarized light is considered. That is, the given linearly polarized light is P-polarized light.

[0200] Figure 19 is a graph showing the transmittance of the first face 51 of the prism 5D to P-polarized light. G51 indicates the transmittance T α with respect to the change in wavelength. G52 indicates the transmittance T θ with respect to the change in wavelength. The transmittance T α indicates the transmittance to light incident to the first face 51 at an angle a (= 10°). The transmittance T θ indicates the transmittance to light incident to the first face 51 at an angle equal to the refractive angle θ (= 80°).

[0201] The reference wavelength of the prism 5D and the antireflection film is 635 nm. The material of the prism 5D is glass, and the refractive index with respect to the wavelength of the reference wavelength is 1.456954. The antireflection film of the prism 5D is a multilayer film obtained by alternately laminating layers composed of materials having different refractive indices with respect to the reference wavelength. The structure of the antireflection film is shown in Table 9 below.

[0202] [Table 9]

[0203]

[0204] According to G51 and G52, in the antireflection film of the structure of Table 9, T α · T θ≥ 90%. W41 is 629 nm, and W42 is 654 nm. Therefore, if the antireflection film is of the structure of Table 9, even if the first surface 51 of the 2x transmission prism 5D is transmitted, the total transmittance (= T α · T θ ) can be ensured to be 90% or more, which is a high transmittance.

[0205] In this way, the prism 5D can adjust the interval, shape, and filling rate of the beams. In particular, by one prism 5D, the substantially parallel light L can be made to approach a circular shape from an elliptical shape, the interval of the substantially parallel light L in the first direction can be narrowed, and the filling rate of the substantially parallel light L can be increased. Therefore, the optical system can be made more compact.

[0206] [1.5.2 Effects, etc.]

[0207] The prism 5D described above satisfies β > α. This structure can narrow the interval of the beams (substantially parallel light L) with a simple configuration, and further, can increase the circularization and filling rate of the beams (substantially parallel light L).

[0208] The prism 5D satisfies b2 / a2 > b1 / a1. This structure can not only reduce the interval of the beams in the first direction, but also increase the filling rate of the beams.

[0209] In the prism 5D, if the refractive index of the prism 5D is assumed to be n, and the refractive angle of the plurality of substantially parallel light L with respect to the emission region R2 is assumed to be θ [°], θ = sin -1 (n · sin (sin -1 (sin α / n) + 2(β - α)) is satisfied. If the transmittance of the incident region R1 to a given straight line (P-polarized light) is assumed to be T α [%], and the transmittance of the emission region R2 to a given straight line (P-polarized light) is assumed to be T θ [%], T α · T θ ≥ 90% is satisfied. This structure can achieve a high transmittance even in the case where refraction at two different angles in the incident region R1 and the emission region R2 exists.

[0210] The prism 5D satisfies γ - 90 < α < γ / 2. This structure can increase the reduction rate and filling rate of the substantially parallel light L in the first direction.

[0211] The prism 5D further satisfies 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60. This structure can further increase the reduction rate and filling rate of the substantially parallel light L in the first direction.

[0212] [1.6 Embodiment 6]

[0213] [1.6.1 Structure]

[0214] Figure 20 is a schematic side view of the light source device 1E according to Embodiment 6, particularly a schematic side view as viewed from the -Y direction. The light source device 1E includes a plurality of laser light sources 2 and an optical system 3E. The optical system 3E includes a plurality of collimators 4 and a prism 5E.

[0215] The prism 5E has the first face 51 and the second face 52 like the prism 5, but differs from the prism 5 mainly in the refractive index n, the angle a, the angle β, the angle γ, and the thickness d.

[0216] One example of parameters of the light source device 1E according to the present embodiment is shown in Table 10 below.

[0217] [Table 10]

[0218]

[0219] In the prism 5E, the rate of change of the first direction of the substantially parallel light L is 222%, exceeding 100%. Therefore, the prism 5E amplifies the beam width of the first direction of the substantially parallel light L. In the substantially parallel light L, the beam width of the first direction is smaller than the beam width of the second direction. Therefore, by amplifying the beam width of the first direction of the substantially parallel light, the substantially parallel light L approaches a circular shape from an elliptical shape. In addition, the prism 5E can reduce the fill factor of the first direction of the substantially parallel light L.

[0220] Figure 21 is a graph showing the transmittance of the first face 51 of the prism 5E for S-polarized light. G61 indicates the transmittance T α G62 indicates the transmittance T θ G62 indicates the transmittance T α G63 indicates the transmittance for light incident on the first face 51 at the angle a (= 70°). The transmittance T θ G64 indicates the transmittance for light incident on the first face 51 at an angle equal to the refractive angle θ (= 20°).

[0221] The reference wavelength of the prism 5E and the antireflection film is 455 nm. The material of the prism 5E is glass, and the refractive index with respect to the wavelength of the reference wavelength is 1.524396. The antireflection film of the prism 5E is a multilayer film obtained by alternately stacking layers composed of materials having different refractive indices with respect to the reference wavelength. The structure of the antireflection film is shown in Table 11 below.

[0222] [Table 11]

[0223]

[0224] According to G61, G62, in the antireflection film of the structure of Table 11, T α ·T θ ≥ 90% in the wavelength range of W51 to W52 including the reference wavelength. W51 is 424 nm, and W52 is 502 nm. Therefore, if it is the antireflection film of the structure of Table 11, even if the first surface 51 of the 2-time transmission prism 5E is transmitted, it is possible to ensure a high transmittance of 90% or more (= T α ·T θ ) of 90% or more.

[0225] In this way, the prism 5E can adjust the interval, the shape, and the filling rate of the beams. In particular, by one prism 5E, it is possible to make the substantially parallel light L approach a circular shape from an elliptical shape, it is possible to widen the interval of the first direction of the substantially parallel light L, and it is possible to reduce the filling rate of the substantially parallel light L. Therefore, it is possible to make the optical system more compact. For example, the prism 5E can widen the distance between the beams B while correcting the shape of the beams B in cases where it is desired to separate the beams B from each laser light source 2 for various uses, cases where the density of the laser light sources 2 is too high, and the like, and it is possible to easily configure the optical system.

[0226] [1.6.2 Effects and the like]

[0227] In the prism 5E described above, if the angle of the incident region R1 and the exit region R2 with respect to the first direction is set as a [°], and the angle of the reflection region R3 with respect to the first direction is set as β [°], β < a is satisfied. This structure can widen the interval of the beams (substantially parallel light L) with a simple configuration, and further, can improve the circularization of the beams (substantially parallel light L) and reduce the filling rate.

[0228] [2. Modified examples]

[0229] The embodiments of the present disclosure are not limited to the above-described embodiments. The above-described embodiments can be variously changed according to design and the like as long as the objects of the present disclosure can be achieved. Modified examples of the above-described embodiments are listed below. The modified examples described below can be appropriately combined and applied.

[0230] In addition, hereinafter, although it is possible to apply to any one of the above-described embodiments 1 to 6, the symbol used in the embodiment 1 is mentioned only for the purpose of simplifying the description, and is not intended to exclude the application to the embodiments 2 to 6.

[0231] Figure 22is a front view of a part of the prism 5 according to Embodiment 1. In the prism 5, the substantially parallel light L is refracted by the entrance region Rl of the first face 51 to enter the prism 5, is reflected by the reflection region R3 of the second face 52 in the prism 5, and is refracted by the exit region R2 of the first face 51 to exit the prism 5. In the prism 5, there is a part where the effect of the refraction and the reflection of the plurality of substantially parallel light L is very small. In particular, in the second face 52, the effect of the reflection of the substantially parallel light L is very small in the part other than the reflection region R3, mainly the second inclined face 52b and the boundary part of the second inclined face 52b and the first inclined face 52a. Depending on the position of the reflection region R3, the peripheral end of the substantially parallel light L can exist in the second inclined face 52b and the boundary part of the second inclined face 52b and the first inclined face 52a, but the peripheral end of the substantially parallel light L is usually a part where the radiation intensity is almost zero in the radiation intensity of the semiconductor laser which is in a Gaussian distribution. Therefore, the part other than the reflection region R3, such as the second inclined face 52b and the boundary part of the second inclined face 52b and the first inclined face 52a, is an ineffective part R4 where the effect on the light use efficiency is very small. Therefore, the shape of such an ineffective part R4 can be any shape.

[0232] Figure 23 is a front view of a part of the prism 5 according to a modification. In the prism 5, Figure 23 in the second face 52, the second inclined face 52b becomes a face along the ±Z direction. Figure 24 is a front view of a part of the prism 5 according to another modification. In the prism 5, Figure 24 in the second face 52, the edge line of the first inclined face 52a and the second inclined face 52b is R-shaped. The prism 5 can be manufactured by polishing, glass molding, resin molding, or the like. In the case where the prism 5 is manufactured by glass molding, since the shape of the prism 5 is determined by the shape of a mold, the shape of the prism 5 is preferably determined so as to be suitable for the shape of the mold. Figure 23 Such a shape, Figure 22 or the aspect ratio of the shape of Fig. 240 is small, so that the shape deformation at the time of molding is easily suppressed, and the demolding of the mold is good.

[0233] The ineffective part R4 of the prism 5 is not limited to Figure 22 to Figure 24 the shape, and the degree of freedom of the ineffective part R4 can be used to set a shape suitable for the manufacturing method of the prism 5.

[0234] In one modification, the plurality of laser light sources 2 can be configured to be mounted on a can (CAN) package one by one, or can be configured to be centralized.

[0235] In one modification, the plurality of collimators 4 can be integrated as one optical member. The plurality of collimators 4 can be provided as a light source unit together with the plurality of laser light sources 2. In this case, the optical system 3 does not need to have the plurality of collimators 4.

[0236] In a modification, the first face 51 can not be a flat face but a stepped face like the second face 52. In this case, the incidence region Rl and the exit region R2 can not be located on the same plane in the first direction. The incidence region Rl or the exit region R2 can be arranged not to be located on the same plane in the first direction. Further, in the case where the first face 51 is a stepped face like the second face 52, the second face 52 can be a flat face.

[0237] In a modification, a reflection film can be formed on the second face 52 of the prism 5, particularly the first inclined face 52a. The reflection film can be a dielectric multilayer film or a metal coating film as long as it has a high reflectance in a desired wavelength range including the wavelength of the substantially parallel light L.

[0238] In a modification, the optical system 3 can not have the mirror group 6. On the other hand, the optical systems 3A, 3B, 3C, 3D, 3E can have the mirror group 6.

[0239] [3. Mode]

[0240] As made clear from the above-described embodiments and modifications, the present disclosure includes the following modes.

[0241] [Mode 1]

[0242] A prism has:

[0243] a first face on which a plurality of substantially parallel lights are incident from a plurality of collimators that set a plurality of beams radiated from a plurality of laser light sources as the plurality of substantially parallel lights; and

[0244] a second face that opposes the first face,

[0245] in each of the plurality of substantially parallel lights incident to the prism, a beam width in a first direction is greater than a beam width in a second direction orthogonal to the first direction,

[0246] the plurality of substantially parallel lights incident to the prism are arranged at least in the first direction,

[0247] with respect to each of the plurality of substantially parallel lights,

[0248] the first face includes an incidence region in which the substantially parallel light is refracted and enters into the prism, and an exit region in which the substantially parallel light is refracted and exits from the prism,

[0249] the second face includes a reflection region that reflects the substantially parallel light that has entered into the prism through the incidence region toward the exit region.

[0250] [Mode 2]

[0251] In the prism of Mode 1,

[0252] If an angle of the incident region and the exit region with respect to the first direction is set as α [°], and an angle of the reflection region with respect to the first direction is set as β [°],

[0253] β ≠ α is satisfied.

[0254] [Mode 3]

[0255] In the prism of Mode 2,

[0256] β > α is satisfied.

[0257] [Mode 4]

[0258] In the prism of Mode 3,

[0259] If a pitch of the first direction of the plurality of substantially parallel lights incident to the prism is set as a1, a beam width of the first direction is set as b1, a pitch of a third direction corresponding to the first direction among the plurality of substantially parallel lights emitted from the prism is set as a2, and a beam width of the third direction is set as b2,

[0260] b2 / a2 > b1 / a1 is satisfied.

[0261] [Mode 5]

[0262] In the prism of Mode 2,

[0263] β < α is satisfied.

[0264] [Mode 6]

[0265] In the prism of any one of Modes 1 to 5,

[0266] If a refractive index of the prism is set as n, and a refraction angle of the plurality of substantially parallel lights with respect to the exit region is set as θ [°],

[0267] θ = sin -1 (n·sin (sin -1 (sin α / n) + 2(β - α)) is satisfied.

[0268] If a transmittance of the incident region to a given linearly polarized light is set as T α [%], and a transmittance of the exit region to the given linearly polarized light is set as T θ [%],

[0269] T α · T θ ≥ 90% is satisfied.

[0270] [Mode 7]

[0271] In the prism of any one of Modes 1 to 6,

[0272] The incident region and the exit region are located on the same plane in the first direction.

[0273] [Mode 8]

[0274] In the prism of any one of Modes 1 to 7,

[0275] The reflection regions are arranged not to be located on the same plane in the first direction.

[0276] [Mode 9]

[0277] In the prism of Mode 8,

[0278] For each of the plurality of substantially parallel lights, the distance between the center of the incident region and the center of the reflection region is equal, and the distance between the center of the exit region and the center of the reflection region is equal.

[0279] [Mode 10]

[0280] In the prism of any one of Modes 1 to 9,

[0281] If the distance on the first plane between the centers of the incident regions of substantially parallel lights adjacent in the first direction among the plurality of substantially parallel lights is set as s [mm],

[0282] the distance on the first plane between the midpoint between the centers and the exit region of the adjacent substantially parallel light close to the midpoint is set as t [mm],

[0283] |2t / s| < 0.3 is satisfied.

[0284] [Mode 11]

[0285] In the prism of Mode 10,

[0286] t = 0 is satisfied.

[0287] [Mode 12]

[0288] In the prism of any one of Modes 1 to 11,

[0289] If the angle of the optical axis of the plurality of substantially parallel lights emitted from the prism with respect to the optical axis of the plurality of substantially parallel lights incident to the prism is set as γ [°],

[0290] γ - 90 < α < γ / 2 is satisfied.

[0291] [Mode 13]

[0292] In the prism of Mode 12,

[0293] Further, 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60 are satisfied.

[0294] [Mode 14]

[0295] A light source device includes:

[0296] a plurality of laser light sources;

[0297] a plurality of collimators that set a plurality of beams emitted from the plurality of laser light sources as a plurality of substantially parallel lights; and

[0298] a prism that has a first surface on which the plurality of substantially parallel lights are incident from the plurality of collimators, and a second surface that opposes the first surface,

[0299] in each of the plurality of substantially parallel lights incident on the prism, a beam width in a first direction is larger than a beam width in a second direction orthogonal to the first direction,

[0300] the plurality of substantially parallel lights incident on the prism are arranged at least in the first direction,

[0301] with respect to each of the plurality of substantially parallel lights,

[0302] the first surface includes an incident region in which the substantially parallel light is refracted and enters into the prism, and an exit region in which the substantially parallel light is refracted and exits from the prism,

[0303] the second surface includes a reflection region that reflects the substantially parallel light that has entered into the prism through the incident region toward the exit region.

[0304] [Mode 15]

[0305] In the light source device of Mode 14,

[0306] the plurality of substantially parallel lights are arranged in both the first direction and the second direction.

[0307] [Mode 16]

[0308] In the light source device of Mode 15,

[0309] the light source device further includes a mirror group that reflects the plurality of substantially parallel lights that exit from the prism,

[0310] The mirror group includes a plurality of mirrors arranged such that the interval of the second direction of the plurality of substantially parallel light beams after being reflected by the mirror group is smaller than the interval of the second direction of the plurality of substantially parallel light beams before being reflected by the mirror group.

[0311] Modes 2 to 13, 15, and 16 are optional elements and are not necessarily required. Modes 2 to 13 can be appropriately combined with modes 14 to 16.

[0312] Industrial applicability

[0313] The present disclosure can be applied to a prism and a light source device. Specifically, the present disclosure can be applied to a prism for converging beams from a plurality of laser light sources, and a light source device provided with the prism.

[0314] -Explanation of symbols-

[0315] 1, 1A, 1B, 1C, 1D, 1E Light source device

[0316] 2 Laser light source

[0317] 3, 3A, 3B, 3C, 3D, 3E Optical system

[0318] 4 Collimator

[0319] 5, 5A, 5B, 5C, 5D, 5E Prism

[0320] 51 First surface

[0321] 52 Second surface

[0322] R1 Incident region

[0323] R2 Emission region

[0324] R3 Reflection region

[0325] 6 Mirror group

[0326] 6a Mirror

[0327] L Substantially parallel light

Claims

1. A prism, comprising: a first surface on which a plurality of substantially parallel lights are incident from a plurality of collimators that set the plurality of substantially parallel lights from a plurality of beams to be radiated from a plurality of laser light sources; and a second surface that opposes the first surface, in each of the plurality of substantially parallel lights incident to the prism, a beam width in a first direction is larger than a beam width in a second direction orthogonal to the first direction, the plurality of substantially parallel lights incident to the prism are arranged at least in the first direction, with respect to each of the plurality of substantially parallel lights, the first surface includes an incident region into which the substantially parallel lights are refracted and enter into the prism, and an exit region from which the substantially parallel lights are refracted and exit from the prism, the second surface includes a reflection region that reflects the substantially parallel lights that have entered the prism through the incident region toward the exit region.

2. The prism according to claim 1, wherein, if an angle of the incident region and the exit region with respect to the first direction is set as a [°], and an angle of the reflection region with respect to the first direction is set as β [°], β > a is satisfied.

3. The prism according to claim 2, wherein, if a pitch of the first direction of the plurality of substantially parallel lights incident to the prism is set as a1, a beam width of the first direction is set as b1, a pitch of a third direction corresponding to the first direction in the plurality of substantially parallel lights that exit from the prism is set as a2, and a beam width of the third direction is set as b2, b2 / a2 > b1 / a1 is satisfied.

4. The prism according to claim 1, wherein, if an angle of the incident region and the exit region with respect to the first direction is set as a [°], and an angle of the reflection region with respect to the first direction is set as β [°], β < a is satisfied.

5. The prism according to claim 1, wherein, if a refractive index of the prism is set as n, and a refraction angle of the plurality of substantially parallel lights with respect to the exit region is set as θ [°], 6. The prism according to claim 1, wherein, the incident region and the exit region are located on the same plane in the first direction.

7. The prism according to claim 1, wherein, the reflection region is arranged not to be located on the same plane in the first direction.

8. The prism according to claim 5, wherein, for each of the plurality of substantially parallel lights, a distance between a center of the incident region and a center of the reflection region is equal, and a distance between a center of the exit region and the center of the reflection region is equal.

9. The prism according to claim 1, wherein, if a distance on the first surface between centers of the incident regions of substantially parallel lights that are adjacent in the first direction among the plurality of substantially parallel lights is set as s [mm], a distance on the first surface between a midpoint between the centers and the exit region of the exit regions of the adjacent substantially parallel lights that is close to the midpoint is set as t [mm], |2t / s| < 0.3 is satisfied. then θ = sin -1 (n sin (sin -1 (sin α / n) + 2(β - α)), If the transmittance of the incident region for a given linearly polarized light is set as T α [%] and the transmittance of the exit region for the given linearly polarized light is set as T θ [%], then T satisfies α • T θ ≥ 90%. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. The prism according to claim 9, wherein t = 0 is satisfied.

11. The prism according to claim 1, wherein if an angle of an optical axis of the plurality of substantially parallel lights emitted from the prism with respect to an optical axis of the plurality of substantially parallel lights incident to the prism is set as γ [°], γ - 90 < α < γ / 2 is satisfied.

12. The prism according to claim 11, wherein 50 < γ < 100 and 1.1γ - 90 < α < 0.95γ - 60 are further satisfied.

13. A light source device, comprising: a plurality of laser light sources; a plurality of collimators that set a plurality of beams emitted from the plurality of laser light sources as a plurality of substantially parallel lights; and a prism that has a first surface on which the plurality of substantially parallel lights are incident from the plurality of collimators, and a second surface that opposes the first surface, in each of the plurality of substantially parallel lights incident to the prism, a beam width in a first direction is larger than a beam width in a second direction that is orthogonal to the first direction, the plurality of substantially parallel lights incident to the prism are arranged at least in the first direction, with respect to each of the plurality of substantially parallel lights, the first surface includes an incident region in which a substantially parallel light is refracted and enters into the prism, and an emission region in which the substantially parallel light is refracted and emitted from the prism, the second surface includes a reflection region that reflects the substantially parallel light that has entered into the prism through the incident region toward the emission region.

14. The light source device according to claim 13, wherein the plurality of substantially parallel lights incident to the prism are arranged in both the first direction and the second direction.

15. The light source device according to claim 14, wherein the light source device further comprises a mirror group that reflects the plurality of substantially parallel lights emitted from the prism, the mirror group includes a plurality of mirrors that are arranged such that a spacing in the second direction of the plurality of substantially parallel lights after being reflected by the mirror group is smaller than a spacing in the second direction of the plurality of substantially parallel lights before being reflected by the mirror group.

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