Light source device and inspection device

Abstract

In the light source device, the LD package is cooled with a simple configuration. [Solution] The light source device 3 comprises an LD package 31 in which a laser diode chip 311 is built-in, a holding unit 32 having an internal flow path 321 that holds the LD package 31 so that a part of the LD package 31 is exposed to the internal flow path 321 and has an opening 331 at a position facing the emission surface 310 of the LD package 31, and a gas supply unit 39 that supplies cooling gas to the internal flow path 321. This allows the LD package 31 to be cooled with a simple configuration.

Description

Technical Field

[0001] The present invention relates to a light source device and an inspection device.

Background Art

[0002] Conventionally, a laser diode (also called a semiconductor laser, hereinafter simply referred to as "LD") has been used as a light source device for various applications. Usually, an LD is handled as an LD package incorporating an LD chip. In addition, a method for cooling the LD package is also known. For example, in the light source device of Patent Document 1, the LD package is cooled by bringing a Peltier element into contact with an LD holder to which the LD package is attached.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a light source device, when a Peltier element is used for cooling an LD package, a cooling water circulation device such as a chiller is required to cool the heat generation surface of the Peltier element. In this case, the manufacturing cost of the device increases. In addition, it is necessary to attach a Peltier element or a water-cooling jacket near the LD package, and there is also a concern about the complication of the wiring and the increase in the weight of the light source device.

[0005] The present invention has been made in view of the above problems, and an object thereof is to cool an LD package with a simple configuration in a light source device.

Means for Solving the Problems

[0006] One aspect of the present invention is a light source device comprising: an LD package having a laser diode chip built in; a holding unit having an internal channel, which holds the LD package such that a part of the LD package is exposed to the internal channel, and which has a light-transmitting portion provided at a position facing the emission surface of the LD package; and a gas supply unit which supplies cooling gas to the internal channel.

[0007] Aspect 2 of the present invention is a light source device according to aspect 1, wherein the light-transmitting portion in the holding unit is an opening, the opening is connected to the internal flow path, and the cooling gas flowing through the internal flow path is discharged to the outside of the holding unit from the opening.

[0008] A third aspect of the present invention is the light source device according to the second aspect, wherein the cross-sectional area of ​​the opening is larger than the cross-sectional area of ​​the internal flow path.

[0009] Aspect 4 of the present invention is a light source device according to Aspect 1 (which may be any one of Aspects 1 to 3), wherein the holding unit comprises a holding portion on which the LD package is fixed and on which the emission surface of the LD package is exposed on one surface, and a cover portion in the vicinity of the LD package that covers the surface of the holding portion and is provided with the light-transmitting portion, and the internal flow path is formed between the surface of the holding portion and the cover portion.

[0010] Aspect 5 of the present invention is a light source device according to aspect 1 (which may be any one of aspects 1 to 4), wherein the LD package is detachably held with respect to the holding unit.

[0011] Aspect 6 of the present invention is an inspection apparatus comprising a light source device according to any one of aspects 1 to 5, an imaging unit that images an object irradiated with light from the light source device and acquires an image, and an inspection unit that inspects the object based on the image. [Effects of the Invention]

[0012] According to the present invention, the LD package can be cooled in a light source device with a simple configuration. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing the configuration of the inspection device. [Figure 2] This is a cross-sectional view showing a light source device. [Figure 3] This is a diagram showing the holding part. [Figure 4] This is a diagram showing the holding unit. [Figure 5] This figure shows another example of a holding unit. [Figure 6] This figure shows yet another example of a holding unit. [Figure 7] This figure shows another example of a holding part. [Modes for carrying out the invention]

[0014] Figure 1 shows the configuration of an inspection device 1 according to one embodiment of the present invention. The inspection device 1 in Figure 1 is an optical visual inspection device for inspecting the appearance of a printed circuit board 9. The inspection device 1 may be a device for inspecting substrates other than the printed circuit board 9, or a device for inspecting objects other than substrates. In Figure 1, three mutually orthogonal directions are indicated by arrows as the X, Y, and Z directions (the same applies to the figures described later). In the example shown in Figure 1, the X and Y directions are mutually perpendicular horizontal directions, and the Z direction is the vertical direction (i.e., up and down direction). Depending on the object being inspected by the inspection device 1, the Z direction may be a different direction from the vertical direction.

[0015] The inspection device 1 comprises an imaging device 2 and a computer 10. The computer 10 has a CPU and the like, and by executing a predetermined program, it realizes an inspection unit 11 and a control unit (not shown). The inspection unit 11 inspects the printed circuit board 9 based on the image acquired by the imaging device 2. That is, it uses the image to detect defects in the printed circuit board 9. The control unit is responsible for the overall control of the inspection device 1. All or part of the inspection unit 11 and the control unit may be realized by dedicated electrical circuits.

[0016] The imaging device 2 comprises a control unit, a stage 21, a stage moving mechanism 22, an illumination unit 4, and an imaging unit 7. In the example shown in Figure 1, the control unit of the inspection device 1 also serves as the control unit of the imaging device 2. The stage 21 holds the printed circuit board 9, which is the object to be imaged by the imaging device 2. In the example shown in Figure 1, the printed circuit board 9 is supported and held by the stage 21 from below (the (-Z) side). The printed circuit board 9 may also be held on the stage 21 by suction or other means. The stage moving mechanism 22 has a motor and a ball screw, etc., and moves the stage 21. The direction of movement of the stage 21 by the stage moving mechanism 22 is, for example, two directions (X direction and Y direction in Figure 1) that are along the main surface of the printed circuit board 9 and are mutually orthogonal. The stage moving mechanism 22 may also have a linear motor, etc.

[0017] The illumination unit 4 comprises a beam splitter 43, a light source device 3, and an optical system 42. The beam splitter 43 is positioned above the stage 21. The beam splitter 43 is, for example, a dichroic prism formed by bonding two right-angle prisms together, and has the shape of a rectangular prism (a regular rectangular prism in the example in Figure 1). A mirror film 44, which is a dielectric multilayer film, is formed at the interface of the two prisms. The mirror film 44 is a dichroic mirror that reflects ultraviolet light and transmits visible light.

[0018] The outer shape of the beam splitter 43 is long in the Y direction and has four side surfaces and two end surfaces. When the beam splitter 43 is viewed along the Y direction, the angle formed by the four side surfaces and the mirror film 44 is 45°. The side surface 431 on the (-Z) side of the beam splitter 43 faces the printed circuit board 9 on the stage 21 and is substantially parallel to the upper surface ((+Z) side surface) of the printed circuit board 9. As will be described later, in the illumination unit 4, since optical elements other than the beam splitter 43 are also long in the Y direction, hereinafter, the Y direction is referred to as the "element longitudinal direction". The beam splitter 43 may be a cross-dichroic prism formed by bonding four right triangular prisms, or may be a plate-type beam splitter in which a mirror film is formed on a thin flat glass. As will be described later, since the light transmitted through the beam splitter 43 is guided to the imaging unit 7, in order to suppress the occurrence of ghosts in the acquired image, it is preferable that the beam splitter 43 is of the prism type.

[0019] The light source device 3 includes one or more laser diode (LD) packages 31 (hereinafter simply referred to as "LD package 31"). The LD package 31 in the present embodiment is, for example, a UV-LD that emits ultraviolet light. The wavelength of the light emitted from the LD package 31 is, for example, 365 nm or 405 nm. In the present embodiment, light having a wavelength of 360 to 409 nm is included in ultraviolet light, and light having a wavelength of 410 to 860 nm is included in visible light. The details of the structure of the light source device 3 will be described later.

[0020] The optical system 42 shapes the light from the light source device 3 and guides it to the beam splitter 43. Specifically, the light emitted from the light source device 3 is shaped by the optical system 42 into a shape in which the cross-section of the light beam extends in the element longitudinal direction, and is incident on the side surface 432 on the (-X) side of the beam splitter 43. The optical elements (such as lenses) included in the optical system 42 are also elongated in the element longitudinal direction. The optical axis J2 (the optical axis J2 between the light source device 3 and the beam splitter 43) of the optical system 42 is perpendicular to the side surface 432 of the beam splitter 43. In this specification, when a certain surface (region) and the optical axis are perpendicular, it includes the case where the two are substantially perpendicular (for example, within the range of 90°±5°, preferably within the range of 90°±3°).

[0021] The ultraviolet light incident on the beam splitter 43 from the optical system 42 is reflected by the mirror film 44. The ultraviolet light reflected by the mirror film 44 is emitted from the side surface 431 on the (-Z) side of the beam splitter 43, and is irradiated onto a region 90 (hereinafter referred to as the "imaging region 90") that extends in the element longitudinal direction on the upper surface of the printed circuit board 9. As will be described later, the imaging region 90 is a region where imaging is performed by the imaging unit 7. In FIG. 1, a reference sign J1 is attached to the optical axis between the side surface 431 of the beam splitter 43 and the printed circuit board 9. The optical axis J1 is perpendicular to the side surface 431 and the imaging region 90 of the printed circuit board 9, and extends along the vertical direction.

[0022] The imaging unit 7 is disposed above the beam splitter 43, and includes an imaging element 71 and an imaging optical system 72. The imaging element 71 in the present embodiment is a line sensor. The line sensor extends in the element longitudinal direction. The imaging optical system 72 includes a plurality of lenses, and the light emitted from the side surface on the (+Z) side of the beam splitter 43 is incident on the imaging optical system 72. The optical axis of the imaging optical system 72 is perpendicular to the side surface. Note that in the imaging unit 7, an area sensor may be used as the imaging element 71.

[0023] Here, the upper surface of the printed circuit board 9 includes a region where a conductive part is formed by a conductive material such as copper, and a region where no conductive material exists (hereinafter referred to as the "background region"). The background region is the region where the substrate or insulating layer of the printed circuit board 9 is exposed. In the background region, for example, a material containing resin (such as epoxy resin) is exposed. As previously described, the illumination unit 4 irradiates the imaging region 90 with ultraviolet light. In the imaging region 90, fluorescence (excited and emitted light) is generated in the background region by the ultraviolet light. Most of the fluorescence is visible light. On the other hand, in the conductive part, i.e., the region covered by the conductive material, no fluorescence is generated, and ultraviolet light is reflected (mainly specularly). A portion of the fluorescence and a portion of the reflected ultraviolet light are incident on the side surface 431 of the beam splitter 43 along the optical axis J1.

[0024] In the beam splitter 43, most of the fluorescence incident on the side surface 431 passes through the mirror film 44. The fluorescence that passes through the mirror film 44 is emitted from the (+Z) side of the beam splitter 43 and incident on the imaging optical system 72 of the imaging unit 7. On the other hand, the reflected ultraviolet light incident on the side surface 431 is reflected by the mirror film 44 and heads towards the optical system 42. Therefore, the reflected ultraviolet light does not incident on the imaging optical system 72. The imaging optical system 72 forms an image of the fluorescence in the imaging region 90 on the imaging surface of the image sensor 71. As a result, a line image showing the fluorescence in the imaging region 90 is acquired.

[0025] In the image acquisition by the imaging device 2 in Figure 1, the stage movement mechanism 22 continuously moves the printed circuit board 9 in a direction perpendicular to the imaging area 90 (i.e., the X direction perpendicular to the longitudinal direction of the element). The image sensor 71 repeatedly acquires line images in parallel with the movement of the printed circuit board 9, thereby acquiring a two-dimensional multi-tone image of the printed circuit board 9 (hereinafter referred to as the "acquired image"). The acquired image is a fluorescence image that shows only fluorescence in the background region. The inspection device 1 can appropriately detect defects that are difficult to detect with reflected light images by performing inspection based on the fluorescence image (acquired image).

[0026] Generally, when observing fluorescence generated by ultraviolet light in an object being inspected, the amount of light is less than when observing reflected visible light. Therefore, in the imaging device 2 described above, the amount of fluorescence generated is increased by using an LD package 31 (LD element), which is a high-power light source. On the other hand, in light source devices employing an LD package, the back surface of the LD package (the surface opposite to the emission surface) is usually cooled using a Peltier element. In this case, a cooling water circulation device such as a chiller is required to cool the heat-generating surface of the Peltier element. As a result, the manufacturing cost of the light source device increases. In addition, it is necessary to attach the Peltier element and a water-cooling jacket near the LD package, which raises concerns about increased complexity of wiring and weight of the light source device. The following describes the details of the structure of the light source device 3, which is capable of cooling the LD package 31 with a simple configuration.

[0027] Figure 2 is a cross-sectional view of the light source device 3, showing a cross-section perpendicular to the Z direction and in a plane containing the optical axis J2 of the optical system 42. In Figure 2, the gas supply unit 39, which will be described later, is also shown as a block. The light source device 3 comprises the LD package 31 described above, a holding unit 32, and a gas supply unit 39. The LD package 31 is an electronic component containing a laser diode (LD) chip 311, and is typically a CAN package. In the example in Figure 2, the light source device 3 includes only one LD package 31. As described above, the light source device 3 may include multiple LD packages 31. The external shape of the LD package 31 is approximately cylindrical with the optical axis J2 as the center. In detail, the LD package 31 has a cylindrical cap portion 312 and a disc-shaped base portion 313. The diameter of the base portion 313 is larger than the diameter of the cap portion 312. The cap portion 312 and the base portion 313 are the outer casing of the LD package 31. In the example shown in Figure 2, the cap portion 312 is positioned on the (+X) side of the base portion 313. The (+X) side end face of the cap portion 312 is the emission surface 310 that emits light (in this case, ultraviolet light). The emission surface 310 faces the (+X) direction. For example, the emission surface 310 is the surface of the cover glass.

[0028] The holding unit 32 holds the LD package 31. The holding unit 32 comprises a holding portion 34, a cover portion 33, and a fixing portion 37. The LD package 31 is fixed to the holding portion 34. The cover portion 33 covers the (+X) side of the holding portion 34. The fixing portion 37 is positioned on the (-X) side of the cover portion 33 and fixes the holding portion 34 to the cover portion 33.

[0029] Figure 3 shows the holding portion 34 as viewed from the (+X) side towards the (-X) direction, and the cover portion 33 is omitted in Figure 3. As shown in Figures 2 and 3, the holding portion 34 comprises a first member 35 and a second member 36. Both the first member 35 and the second member 36 are disc-shaped with the optical axis J2 as the center, and the diameter of the first member 35 is larger than the diameter of the second member 36. The first member 35 and the second member 36 are superimposed in the X direction (i.e., the direction of the optical axis J2), with the first member 35 positioned on the (+X) side of the second member 36. The first member 35 and the second member 36 are provided with holes (only the hole in the first member 35 is denoted by reference numeral 359) at positions where they overlap each other, and the first member 35 and the second member 36 are fixed to each other in contact by fastening screws inserted into these holes. The first member 35 and the second member 36 are formed from a metal with high thermal conductivity, such as copper or aluminum.

[0030] A circular retaining hole 351 is provided in the first member 35 at a position where it intersects with the optical axis J2. A step is provided on the inner circumferential surface of the retaining hole 351, and the diameter of the (+X) side portion is smaller than that of the (-X) side portion. That is, the retaining hole 351 includes a small diameter portion located on the (+X) side and a large diameter portion located on the (-X) side. The LD package 31 is inserted into the retaining hole 351 from the (-X) side of the first member 35 with the first member 35 and the second member 36 separated. The diameter of the cap portion 312 of the LD package 31 is smaller than that of the small diameter portion, and the cap portion 312 is located within the small diameter portion. The diameter of the base portion 313 is larger than that of the small diameter portion and smaller than that of the large diameter portion. The base portion 313 is located within the large diameter portion.

[0031] Furthermore, the thickness of the base portion 313 in the X direction is approximately the same as the depth of the large diameter portion. When the first member 35 and the second member 36 are fixed together, the base portion 313 of the LD package 31 is sandwiched between the step on the inner circumferential surface of the holding hole 351 and the second member 36, thereby fixing the LD package 31 to the holding portion 34. The second member 36 is provided with holes into which the leads of the LD package 31 are inserted (in practice, they are inserted together with the insulating sleeve). A connection terminal 381 is attached to the tip of the lead protruding from the (-X) side of the second member 36. Power is supplied to the LD package 31 via the connection terminal 381.

[0032] With the LD package 31 fixed to the holding portion 34, the end face of the cap portion 312, i.e., the ejection surface 310, is exposed to the surface 352 of the first member 35 opposite to the second member 36 (the (+X) side surface facing the cover portion 33, hereinafter referred to as the "opposing surface 352"). A groove portion 353 recessed to the (-X) side is formed on the opposing surface 352. The groove portion 353 extends in the Y direction. As shown in Figure 3, the length of the groove portion 353 in the Y direction is slightly smaller than the diameter of the first member 35. The width of the groove portion 353 in the Z direction is approximately the same as the diameter of the holding hole 351 (the diameter of the small diameter portion) on the opposing surface 352.

[0033] On the bottom surface (the (-X) side) of the groove 353, connection ports 322 are provided at both ends in the Y direction, passing through the first member 35. A gas plug 391 is inserted into the connection port 322 from the (-X) side. A gas supply unit 39 is connected to each gas plug 391 via a gas pipe. The gas supply unit 39 supplies a predetermined gas to the connection port 322. As will be described later, this gas is used to cool the LD package 31, and therefore, hereafter, this gas will be referred to as "cooling gas". An example of cooling gas is compressed air, in which case the gas supply unit 39 includes a compressor, etc. Compressed air that is constantly generated in the factory may be used as the cooling gas, in which case the part connecting the compressed air supply pipe in the factory to the gas plug 391 is considered as the gas supply unit 39. The cooling gas may also be a gas other than compressed air (for example, an inert gas such as nitrogen).

[0034] Figure 4 shows the holding unit 32 viewed from the (+X) side towards the (-X) direction. In Figure 4, the second member 36 and the fixing part 37 of the holding part 34 are shown by thin dashed lines, and the first member 35 of the holding part 34 is shown by a thick dashed line. As shown in Figures 2 and 4, the cover part 33 is a plate-like shape that is perpendicular to the optical axis J2 and long in the longitudinal direction of the element (Y direction). The cover part 33 is made of a metal such as aluminum or stainless steel. A circular opening 331 is provided in the cover part 33 at a position where it intersects with the optical axis J2. The opening 331 faces the output surface 310 of the LD package 31 and is a light-transmitting part through which light from the LD package 31 passes. The diameter of the opening 331 is larger than the diameter of the cap part 312 of the LD package 31. The cross-sectional area of ​​the opening 331 is constant along the optical axis J2. A recess 332 is formed on the (-X) side surface of the cover portion 33, recessed to the (+X) side. The shape of the recess 332, as viewed along the X direction, is circular with the optical axis J2 at its center. The diameter of the recess 332 is slightly larger than the diameter of the first member 35 of the holding portion 34. The thickness of the first member 35 in the X direction is approximately the same as the depth of the recess 332. The first member 35 is housed within the recess 332.

[0035] As shown in Figures 3 and 4, the fixing portion 37 has two fixing members 371. Each fixing member 371 is plate-shaped, perpendicular to the optical axis J2 and elongated in the longitudinal direction (Y direction) of the element. The two fixing members 371 are positioned on the (-X) side of the cover portion 33, and on the (+Z) side and (-Z) side of the second member 36, respectively. In detail, as shown in Figure 3, the edge of each fixing member 371 on the second member 36 side has a notch 372 cut out in an arc shape along the outer edge of the second member 36. The notch 372 is close to the second member 36 with a small gap between them. The portion of the fixing member 371 near the notch 372 overlaps with the first member 35 in the X direction.

[0036] Furthermore, as shown in Figure 4, the fixing member 371 contacts the (-X) side surface of the cover portion 33 on the outside of the recess 332. In Figure 2, the background fixing member 371 is shown with a dashed line. The fixing member 371 and the cover portion 33 are provided with holes 379 and 339 (see Figures 3 and 4) at positions that overlap each other, and the fixing member 371 and the cover portion 33 are fixed to each other in contact by fastening screws inserted into these holes 379 and 339. As a result, the first member 35 is sandwiched between the bottom surface of the recess 332 and the fixing member 371, and the holding portion 34 is fixed to the cover portion 33. Note that in the Z direction, a gap is provided between each fixing member 371 and the gas plug 391, allowing for fine adjustment of the rotational position of the holding portion 34 around the optical axis J2.

[0037] The LD package 31 can be replaced in the holding unit 32. When replacing the LD package 31, the screws inserted into the holes 379 and 339 are loosened, and the holding part 34 is removed from the cover part 33. Next, the screws inserted into the hole 359 are loosened, and the first member 35 and the second member 36 are separated. After replacing the LD package 31 with a new LD package 31, the first member 35 and the second member 36 are fixed with screws, and then the holding part 34 is fixed with screws to the cover part 33. In this way, because the LD package 31 is detachable from the holding unit 32, the replacement of the LD package 31 can be easily performed.

[0038] As previously described, a groove 353 is formed on the opposing surface 352 of the first member 35, and as shown in Figures 2 and 4, an internal flow path 321 extending in the Y direction is provided between the groove 353 and the bottom surface of the recess 332 of the cover portion 33. The internal flow path 321 extends from one connection port 322 to the other connection port 322 in the groove 353. The exit surface 310 of the LD package 31 is exposed to the internal flow path 321. The opening 331 of the cover portion 33 is connected to the internal flow path 321. Because the depth of the groove 353 is relatively small, the cross-sectional area of ​​the internal flow path 321 perpendicular to the Y direction is sufficiently smaller than the opening area of ​​the opening 331 (area perpendicular to the optical axis J2), except for the position of the opening 331. The cross-sectional area of ​​the internal flow path 321 is, for example, less than 1 / 2 of the opening area of ​​the opening 331, and preferably less than 1 / 4 (for example, 1 / 20 or more). Thus, the internal flow path 321 is a narrow flow path.

[0039] As previously described, the gas supply unit 39 supplies cooling gas to each connection port 322. An example of the cooling gas is compressed air, which is approximately the same temperature as the ambient temperature (for example, within a range of ±10°C) or lower than the ambient temperature. The cooling gas is pre-cleaned using a filter or the like (i.e., clean air). The cooling gas supplied from the connection port 322 into the internal flow path 321 flows through the internal flow path 321 toward the optical axis J2. Near the optical axis J2, the cooling gas collides with the upper part of the cap portion 312 of the LD package 31 that protrudes from the bottom surface of the groove portion 353, and the cap portion 312 is cooled by the cooling gas. In the LD package 31, by cooling the surface side closer to the LD chip 311, it is possible to efficiently cool the LD chip 311. In addition, when the cooling gas flowing through the internal flow path 321 is released into the atmosphere at the opening 331 facing the cap portion 312, it undergoes adiabatic expansion, causing a decrease in the temperature of the cooling gas. As a result, it is possible to further cool the LD package 31.

[0040] In the holding unit 32, the cover portion 33 and the holding portion 34 that form the internal flow path 321 are also cooled by the cooling gas. Since the holding portion 34 that contacts the LD package 31 is made of a material with high thermal conductivity (such as copper or aluminum), the base portion 313 of the LD package 31 is also cooled by the holding portion 34.

[0041] As described above, the light source device 3 in Figure 2 comprises an LD package 31 containing an LD chip 311, a holding unit 32, and a gas supply unit 39. The holding unit 32 has an internal flow channel 321 and holds the LD package 31 so that a part of the LD package 31 is exposed to the internal flow channel 321, and a light-transmitting section (opening 331 in the above description) is provided at a position facing the emission surface 310 of the LD package 31. The gas supply unit 39 supplies cooling gas to the internal flow channel 321. As a result, the light source device 3 can cool the LD package 31 with a simple configuration without using a Peltier element or a cooling water circulation device. As a result, the amount of fluorescence light generated can be increased while reducing the manufacturing cost of the light source device 3 and the inspection device 1 including the light source device 3, imaging unit 7, and inspection unit 11. Furthermore, it is possible to avoid increased wiring complexity and weight of the light source device 3.

[0042] Incidentally, high-power light (ultraviolet light in the above case) has the property of attracting airborne particles due to its photo-collection effect. When these airborne particles adhere to the cover glass or optical lens of the LD package, the optical quality deteriorates, such as a decrease in the amount of light irradiated onto the imaging area 90. This phenomenon is particularly pronounced in environments where a large amount of organic solvents are present.

[0043] In contrast, in the preferred light source device 3, the light-transmitting portion in the holding unit 32 is an opening 331, and the opening 331 is connected to an internal flow path 321. Furthermore, the cooling gas flowing through the internal flow path 321 is discharged to the outside of the holding unit 32 from the opening 331. By purging the cooling gas from the opening 331 in this way, the adhesion of airborne particles to the LD package 31 due to the light dust collection effect can be suppressed. As a result, the imaging device 2 can acquire imaging images of stable quality. In addition, because the cross-sectional area of ​​the opening 331 is larger than the cross-sectional area of ​​the internal flow path 321, the LD package 31 can be cooled more efficiently by utilizing the temperature drop of the cooling gas due to adiabatic expansion. Depending on the design of the holding unit 32, the cross-sectional area of ​​the opening 331 may be less than or equal to the cross-sectional area of ​​the internal flow path 321.

[0044] Preferably, the holding unit 32 includes a holding portion 34 on which the LD package 31 is fixed and on which the output surface 310 of the LD package 31 is exposed on one surface (in the above case, the opposing surface 352), and a cover portion 33 in the vicinity of the LD package 31 that covers the surface of the holding portion 34 and is provided with the light-transmitting portion. An internal flow path 321 is formed between the surface of the holding portion 34 and the cover portion 33. This makes it easy to form an internal flow path 321 through which cooling gas flows.

[0045] Various modifications are possible for the light source device 3 and inspection device 1 described above.

[0046] As shown in Figure 5, a transparent member 333 that transmits light emitted from the LD package 31 may be provided in the opening 331 of the cover portion 33 of the holding unit 32. In the holding unit 32, it is sufficient that a light-transmitting portion that transmits light from the LD package 31 is provided at a position facing the emission surface 310 of the LD package 31. In the example in Figure 5, the cooling gas supplied to one connection port 322 and flowing into the internal flow path 321 passes between the transparent member 333 and the LD package 31, reaches the other connection port 322, and is discharged to the outside (see arrows A1 and A2 in Figure 5). Even in this case, it is possible to properly cool the LD package 31.

[0047] As shown in Figure 6, an internal flow path 321 may be formed between the opposing surface 352 of the holding portion 34 and the cover portion 33 by providing a recess 334 on the surface of the cover portion 33 that faces the opposing surface 352 of the holding portion 34. Alternatively, a connection port 322 for connecting to the internal flow path 321 may be provided in the cover portion 33.

[0048] The shape of the internal flow channel 321, as viewed along the optical axis J2, is not limited to a shape extending in one direction. For example, a circular internal flow channel 321 (groove 353) may be provided as shown in Figure 7. In the internal flow channel 321 of Figure 7, a plurality of connection ports 322 are provided at regular angular intervals in the circumferential direction centered on the optical axis J2, and cooling gas flows from each connection port 322 toward the opening 331 (shown by a dashed line in Figure 7) (see arrow A3 in Figure 5). A flow straightening plate (guide plate) may be provided on the bottom surface of the groove 353 (or the cover portion 33) to straighten the flow of cooling gas toward the opening 331.

[0049] Depending on the design of the holding unit 32, the holding portion 34 and the cover portion 33 may be integrally formed. The LD package 31 may be fixed to the holding unit 32 by welding and may not be detachable from the holding unit 32.

[0050] If the light source device 3 includes multiple LD packages 31, each of the multiple LD packages 31 may be held in a multiple holding section 34. Alternatively, each of the multiple LD packages 31 may be held in a single holding section 34. In this case, one internal flow path 321 may be provided for each of the multiple LD packages 31, or the internal flow paths 321 may be provided individually.

[0051] The LD package 31 may have a structure other than a CAN package. Furthermore, the light emitted from the LD package 31 may be light other than ultraviolet light.

[0052] The imaging unit 7 may acquire an image by receiving the reflected light from the printed circuit board 9 that is emitted from the LD package 31. The imaging unit 7 only needs to acquire an image by imaging the printed circuit board 9 that is illuminated by light from the light source device 3.

[0053] In the inspection device 1, the stage 21 may be fixed, and a moving mechanism may be provided that moves the illumination unit 4 and the imaging unit 7 together.

[0054] The object being inspected in the inspection device 1 may be something other than the printed circuit board 9. The light source device 3 may be used for purposes other than inspection.

[0055] The configurations in the above embodiments and each modified example may be combined as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0056] 1. Inspection device 3 Light source device 7 Imaging Unit 9 Printed circuit boards 11. Inspection Department 31 LD package 32 Holding Unit 33 Cover section 34 Holding part 39 Gas Supply Department 310 Ejection surface 311 LD chip 321 Internal flow path 331 Opening 352 Opposing surfaces

Claims

1. A light source device, An LD package with a built-in laser diode chip, A holding unit having an internal flow path, which holds the LD package such that a portion of the LD package is exposed to the internal flow path, and which has a light-transmitting portion provided at a position facing the emission surface of the LD package, A gas supply unit that supplies cooling gas to the internal flow path, A light source device equipped with the following features.

2. A light source device according to claim 1, The light-transmitting portion in the holding unit is an opening, and the opening is connected to the internal flow path. A light source device in which the cooling gas flowing through the internal channel is discharged to the outside of the holding unit through the opening.

3. A light source device according to claim 2, A light source device in which the cross-sectional area of ​​the opening is larger than the cross-sectional area of ​​the internal flow path.

4. A light source device according to claim 1, The holding unit, The LD package is fixed to a holding portion on which the ejection surface of the LD package is exposed on one surface, In the vicinity of the LD package, a cover portion covers the surface of the holding portion and is provided with the light-transmitting portion, Equipped with, A light source device in which the internal flow path is formed between the surface of the holding portion and the cover portion.

5. A light source device according to claim 1, A light source device in which the LD package is detachably held with respect to the holding unit.

6. An inspection device, A light source device according to any one of claims 1 to 5, An imaging unit captures an image of an object illuminated by light from the aforementioned light source device and acquires an image of that object. An inspection unit that inspects the object based on the captured image, An inspection device equipped with the following features.

Images