TW202323804A - Inspection system, and spot lighting device for inspection - Google Patents

Abstract

This inspection system comprises a spot lighting device for inspection, provided with a light source body and a light emitting surface for emitting light emerging from the light source body as inspection light, and an imaging device including an object-side telecentric optical system for imaging a workpiece, the inspection system being configured such that the inspection light emitted from the light emitting surface is shone onto the workpiece coaxially with an optical axis of the imaging device, wherein the light source body is configured using a semiconductor laser.

Description

Detection system and spotlight lighting device for detection

The present invention relates to an inspection system and a spotlight lighting device for inspection used in the inspection system, which is used to irradiate light on, for example, a workpiece, and photograph, for example, the appearance, scratches, defects, etc. of the workpiece.

In the prior art, there is known a detection system, which is a so-called coaxial projection structure, which is constituted to have: an illumination device that emits detection light that irradiates the workpiece; The object-side telecentric optical system of the workpiece; and the detection light emitted by the illuminating device can be irradiated on the workpiece from the same axis as the optical axis of the photographing device (for example, Patent Document 1). In the conventional technology, the inspection system here uses a surface light source that arranges many LED crystal grains on a plane as the light source body of the lighting device. [Prior art literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2021-085815

[Problem to be solved by the invention]

The team of inventors in this case discovered for the first time that the detection system with the above-mentioned object-side telecentric optical system for the coaxial epi-projection structure has the following problem: the higher the optical magnification of the optical system is set, the larger the F value will be. tendencies; for example, in the case of shooting at a high magnification of 2x or more, the brightness (exposure level) at the time of shooting will decrease compared to the case of shooting at a low magnification.

As a result of careful research to solve this problem, the inventor team of this case considered that by narrowing the light distribution characteristics (for example, below 5°) of the lighting device that emits the detection light, the light emitting surface of the lighting device is increased. If the radiant luminance is high, even in a high-magnification object-side telecentric optical system, it may still be expected to increase the brightness when shooting. However, it is very difficult to realize such a narrow light distribution characteristic and high luminance lighting device in the conventional lighting device using LED as a light source with Lambertian distribution characteristics and a surface light source.

In view of this, the present invention was developed to solve the above-mentioned problems, and its main problem is: in a detection system with a high-magnification object-side telecentric optical system with a coaxial epi-projection structure, the brightness during shooting is improved. [Technical means to solve the problem]

That is, the detection system of the present invention is provided with: a spotlight illuminating device for detection, having a light source body, and a light emitting surface that emits the light emitted by the light source body as detection light; Side-telecentric optical system; the detection system is configured to irradiate the workpiece with the detection light emitted from the light exit surface on the same axis as the optical axis of the photographing device; the detection system is characterized in that the light source system Constructed using semiconductor lasers.

According to the detection system of the present invention constituted in this way, by using the semiconductor laser which is a point light source to form the light source body of the concentrating lighting device for detection, compared with the conventional light source body using LEDs, it can reduce Narrow light distribution characteristics, and increase the radiance of the light exit surface; therefore, when combined with a high-magnification object-side telecentric optical system, it can increase the radiance of the image plane of the photographic device and increase the brightness when shooting.

However, in the case of using a semiconductor laser to form the light source body, if the laser light emitted by the semiconductor laser is directly irradiated on the surface of the workpiece, there will be a problem caused by the asymmetry of the light distribution of the laser light, which will cause the surface of the workpiece to be damaged. The uniformity of the irradiance may be reduced.

Therefore, the detection system is preferably: the light source body is used to directly emit the laser light emitted by the semiconductor laser; Diffusion Department. In this way, the symmetry of the light distribution can be improved by diffusing the laser light emitted from the light source body by the light diffusion part, so while improving the brightness during shooting, the irradiance on the workpiece surface can still be increased. Uniformity.

As a specific aspect of the light diffusion part, it can be mentioned: a spot eliminater arranged between the light source body and the light exit surface, or a light beam formed by applying surface texture treatment to the light exit surface, for example. Diffusion surface etc.

Also, in the detection system, as another aspect for improving the uniformity of irradiance on the workpiece surface, it is preferable that the light source body has the semiconductor laser and the phosphor, and is configured such that the semiconductor laser The emitted laser light is irradiated on the phosphor to emit secondary light generated by excitation. In this case, since the light source body is configured as a so-called laser fluorescent type, that is, the laser light (excitation light) emitted by a semiconductor laser is irradiated on the phosphor to excite it, so that the phosphor emits light. The symmetry of light distribution is higher than that of laser light, and it can emit light with high luminance like laser light, so that the uniformity of radiant illumination on the workpiece surface can be improved while improving the brightness during shooting.

As the optical characteristics of the concentrating lighting device included in the detection system, the etendue of the light source body is preferably less than 1 mm ² sr; and the direction angle of the detection light emitted from the light exit surface is preferably Within ±5°. With such a light distribution characteristic, when combined with a high-magnification object-side telecentric optical system, the detection light can reach the workpiece with high utilization efficiency, which can fully increase the irradiance on the image plane of the photographing device and improve the imaging efficiency. brightness at the time. Here, the so-called "the etendue of the light source body" refers to the etendue of the semiconductor laser when the light source body is configured to directly emit the laser light emitted by the semiconductor laser; In the case of emitting secondary light generated from a phosphor irradiated with laser light, it means the etendue of the phosphor.

In addition, if the detection system is equipped with an optical system between the light source body and the light exit surface to guide the light emitted by the light source body to the light exit surface, it is preferable to make each position of the optical system The etendue is below 1mm ² ·sr; more preferably, the etendue near the light exit surface is below 1mm ² ·sr.

Moreover, as an aspect which exhibits the effect of this invention remarkably, the thing which makes the optical magnification of this object side telecentric optical system 2 times or more is mentioned.

In addition, the spotlight illuminating device for detection of the present invention is used together with an imaging device having an object-side telecentric optical system for photographing a workpiece. The light emitting surface used as the detection light is emitted; it is characterized in that the light source system is formed by using a semiconductor laser. If it is such a spotlight illumination device for detection, it can exert the same function and effect as the above-mentioned detection system of the present invention. [Effect of Invention]

According to the present invention thus constituted, the detection system of the object-side telecentric optical system having a high magnification with a coaxial epi-projection structure can improve the brightness during shooting.

＜First Embodiment＞ Hereinafter, the detection system 100 using the detection spotlighting device 1 according to the first embodiment of the present invention will be described with reference to each figure.

This detection system 100 is provided with: a spotlight illumination device 1 for detection, which emits detection light irradiated on the workpiece W; . As shown in FIG. 1 , this detection system 100 is a so-called coaxial epi-ejection structure, which is configured to use a half mirror 232 so that the detection light emitted by the detection spotlight illuminating device 1 passes from the distance between the imaging device 2 and the imaging device 2. The workpiece W is irradiated on the same axis as the optical axis C2.

The spot lighting device 1 used for detection, as shown in FIG. The optical system 13 in front of the light emitting direction of the light source body 12 . In addition, the spotlight illuminating device 1 for detection refers to the illuminating device 1 in which the light emitting surface 1s can be placed near a position conjugate to the position of the aperture diaphragm 22a of the object-side telecentric optical system without using an optical fiber. .

The lighting housing 11 is in the shape of a rotating body, and has: a barrel part 111, which is cylindrical in shape, and accommodates the light source body 12 or a wiring board, etc.; . The end portion 112 is smaller in diameter than the barrel portion 111, and the above-mentioned light emitting surface 1s is formed on the end face. The end portion 112 is configured to be inserted into an illumination attachment port 231 a provided in the camera lens 22 of the photographing device 2 described later, so as to emit light into the camera lens 22 .

The light source body 12 has a light emitting area smaller than that of an LED (for example, 0.1 mm ² or less), has a high luminance, and is composed of a semiconductor laser 12a (LD) that emits laser light. As the semiconductor laser 12a, a known structure is used. The light source body 12 of the present embodiment is configured to emit the laser light (primary light) emitted by the semiconductor laser 12a directly toward the optical system 13; on the optical axis C1.

The optical system 13 is arranged between the light source body 12 and the light exit surface 1s, and guides the laser light emitted by the light source body 12 to the light exit surface 1s. Specifically, the optical system 13 includes a collimator lens 131 , a light diffusing element 132 , and a lenticular lens 133 in order along the optical axis direction from the base end to the end portion 112 . The collimator lens 131, the light diffusing element 132, and the lenticular lens 133 are provided so that their optical axis directions coincide with each other.

The collimator lens 131 is used to condense the laser light emitted by the light source body 12 placed at the focal point 13f to make it approach parallel light (collimated light).

The light diffusing element 132 is used to reduce speckle noise by diffusing the laser light that has passed through the collimating lens 131 to reduce its coherence; specifically, it is a speckle remover. The specific configuration of the light diffusing element 132 is not particularly limited, but for example, a frosted diffuser plate vibrates with a vibrating motor or the like.

The lenticular lens 133 has a cylindrical shape and is disposed inside the end of the lighting housing 11 so that its axial direction coincides with the optical axis C1 of the optical system 13 . The lenticular lens 133 guides the light that has passed through the light diffusing element 132 to the inside from the base end surface along the axial direction, and reduces the unevenness of the light amount traveling inside, and from the light exit surface 1s formed on the end surface toward the inside. External shot. The end surface of the lenticular lens 133 which is the light exit surface 1s is subjected to surface texture treatment so that the light exit surface 1s functions as a light diffusing surface to diffuse the outgoing light.

The optical characteristics of the detection spotlight illumination device 1 of the present embodiment configured in this way will be described. In this concentrating lighting device 1 for detection, by using the semiconductor laser 12a to form the light source body 12, the radiation luminance of the light exit surface 1s can be increased and the light distribution characteristic can be narrowed. In the spotlight illumination device 1 for detection of this embodiment, the directivity angle (or half-value angle) of the detection light emitted from the light emission surface 1s is within ±5°. The directing angle refers to the angle where the direction with the strongest radiation intensity in the light distribution characteristics is 0°, and the relative radiation intensity is more than 50% of the peak value. In addition, the etendue of the light source body 12 (semiconductor laser 12 a in this embodiment) is 1.0 mm ² ·sr or less, more specifically, 0.01 mm ² ·sr or less. The etendue is represented by the product of the cross-sectional area of the beam and the solid angle (sphericity), and is represented by the following formula (1). E=S×sinθ ² ×π (1) Here, E: Etendue [mm ² ·sr], S: Light emitting area of the light source body [mm ² ], θ: Radiation angle of the light source body.

Also, in the present embodiment, it is configured such that the etendue at each position of each optical system 13 between the light source body 12 and the light exit surface 1s (preferably in the vicinity of the light exit surface 1s) should be within ^1mm2・sr or less.

The imaging device 2 includes: a camera body 21 having an imaging element 21a; and a camera lens 22 attached to the camera body 21 to image light reflected or scattered by the workpiece W.

The camera lens 22 has an object-side telecentric optical system (hereinafter also referred to as an object-side telecentric lens) configured so that the optical axis C2 and the chief ray are parallel to the workpiece W side (object side), and has: A plurality of lenses in a cylindrical lens housing 221 extending along the optical axis direction (shooting direction), and an aperture diaphragm 22a. In the camera lens 22, an object-side telecentric optical system is formed by arranging the aperture stop 22a at the focus position 22f of the front-side lens group among the plurality of lenses. In the camera lens 22, each lens is arranged so that its optical magnification becomes a high magnification of 2 times or more.

The camera lens 22 is provided with a coaxial epi-projection portion 23, and guides the detection light emitted from the spotlighting device 1 for detection described above into the interior, and at the same time changes the direction of the introduced detection light so as to coincide with the imaging direction. Specifically, as shown in FIG. 1 , the coaxial projection unit 23 includes an illumination mounting portion 231 to which the end portion 112 of the spotlighting device 1 for detection is mounted, and a half mirror 232 that reflects the detection light and changes its direction.

The lighting mounting part 231 is provided on the side surface of the lens housing 221 and is cylindrical in shape extending in a direction perpendicular to the axial direction thereof. At the end thereof, an illumination installation opening 231a into which the end portion 112 of the spotlighting device 1 for inspection is inserted is formed.

The half mirror 232 is provided in the lens case 221 at a position closer to the workpiece W than the position of the aperture stop 22a and facing the light exit surface 1s inserted from the illumination mounting port 231a. The half mirror 232 is inclined at about 45° with respect to the shooting direction.

In the coaxial epi-projection unit 23 having such a configuration, by inserting the end portion 112 of the spotlight illuminator 1 for detection into the illumination installation port 231a, the light emitting surface 1s of the spotlight illuminator for detection 1 is placed on the same side as the camera lens. 22 near the position conjugate of the aperture aperture 22a.

According to the detection system 100 of the first embodiment constituted in this way, the light source body 12 of the spotlight lighting device 1 is constituted by using the semiconductor laser 12a which is a point light source, and the laser light emitted by the semiconductor laser 12a is configured to directly Compared with those using LED as the light source body 12, the radiance of the light exit surface 1s can be improved, and the light distribution characteristics can be narrowed; therefore, when combined with a high-magnification object-side telecentric optical system, the The high utilization efficiency enables the detection light to reach the workpiece, which can increase the irradiance on the image plane of the photographing device 2 and improve the brightness during shooting.

Moreover, since the spotlight remover 132 for diffusing the laser light emitted by the light source body 12 is provided in the concentrating lighting device 1 for detection, and a light diffusing surface formed by surface texture treatment is provided on the light emitting surface 1s, Therefore, the symmetry of the light distribution can be improved by diffusing the laser light emitted by the light source body 12 , and the uniformity of the irradiance on the surface of the workpiece W can be improved while improving the brightness during shooting.

＜Second Embodiment＞ Next, an inspection system 100 using the inspection spotlighting device 1 according to the second embodiment of the present invention will be described focusing on features different from those of the first embodiment.

The detection system 100 of the second embodiment has the same overall configuration as the detection system 100 of the first embodiment shown in FIG. 1 . The spot lighting device 1 for detection according to the second embodiment is characterized in that the light source body 12 is a laser fluorescent type. Specifically, as shown in FIG. 3 , this light source body 12 is provided with a plurality of semiconductor lasers 12a and a phosphor 12b, and is configured to irradiate the "laser light (excitation light) emitted by the plurality of semiconductor lasers 12a to The phosphor 12b is excited so that the secondary light generated by the phosphor 12b is emitted. The light source body 12 is also called SLD (Super Luminescent Diode; Super Diode) light source, etc., and has a broad spectrum like a light emitting diode (LED), and its coherence is lower than that of the semiconductor laser 12a, and it is like a semiconductor laser. 12a generally emits high-intensity light.

In the present embodiment, the phosphor 12b is granular and has a rectangular light-emitting surface with four sides of about 0.5 mm, and is arranged on the optical axis C1 so that the light-emitting surface is perpendicular to the optical axis C1 of the optical system 13 . The plurality of semiconductor lasers 12a, which emit blue wavelength laser light here, are arranged to irradiate the light emitting surface of the phosphor 12b from obliquely front. Specifically, each semiconductor laser 12a is arranged such that the angle formed by its outgoing light axis and the light emitting surface of the phosphor 12b is approximately 45°.

Then, in this embodiment, the spotlighting device 1 for detection includes a collimator lens 131 provided in front of the light source body 12 as the optical system 13 . The collimating lens 131 is arranged such that its optical axis C1 is coaxial with the end portion 112 of the cylindrical illuminating housing 11 . In this embodiment, no optical elements such as the lenticular lens 133 are provided inside the end portion 112 , and it is hollow to form an internal space S through which the light passing through the collimator lens 131 passes. Then, the end face of the end portion 112 where the internal space S is opened will be the light exiting face 1s.

The optical characteristics of the detection spotlight illumination device 1 of the present embodiment configured in this way will be described. In this concentrating lighting device 1 for detection, by using a laser fluorescent type as the light source body 12, the radiance of the light emitting surface 1s can be increased and the light distribution characteristic can be narrowed. Specifically, in the spotlight illumination device 1 for detection of this embodiment, the directivity angle (or half-value angle) of the light emitted from the light exit surface 1s is within ±5°; more specifically, within ±3.5°. Also, the etendue of the light source body 12 (specifically, the phosphor 12 b ) is 1.0 mm ² ·sr or less; more specifically, 0.6 mm ² ·sr or less.

According to the detection system 100 of the second embodiment constituted in this way, by using the semiconductor laser 12a which is a point light source as the light source body 12 of the concentrating lighting device 1, compared with the use of LEDs as the light source body 12, the improvement can be improved. The radiant luminance of the light exit surface 1s is further narrowed and the light distribution characteristics are narrowed; therefore, in the case of combination with a high-magnification object-side telecentric optical system, the detection light can reach the workpiece with high utilization efficiency, and the imaging device 2 can be improved. The irradiance of the image surface improves the brightness when shooting.

And because this detecting spot lighting device 1 uses a so-called laser fluorescent type as the light source body 12, that is, the laser light (excitation light) emitted by the semiconductor laser 12a is irradiated to the phosphor 12b to excite it. , so that the phosphor 12b emits light, so the symmetry of the light distribution is higher than that of laser light, and it can emit light with high brightness like laser light; therefore, while improving the brightness when shooting, it can still be raised on the W surface of the workpiece Uniformity of irradiance.

＜Simulation of light distribution characteristics＞ Next, the results of simulating the light distribution characteristics of a plurality of types of spotlight illumination devices for detection with different configurations of light source bodies are shown in FIG. 4 . In this simulation result, the light distribution characteristics of the following are respectively shown: (i) The light source body is configured as a spotlight illumination device for detection (marked as LD) that directly emits light emitted by a semiconductor laser, (ii) The light source body is configured to irradiate the laser light emitted by the semiconductor laser to the phosphor, and the secondary light generated by its excitation is emitted. Concentrated lighting device for detection (marked as LED) configured to emit the light emitted by the light-emitting diode. In this simulation, in (i) the spotlight illumination device (LD) for detection, the collimator lens and the spot remover are arranged in front of the light emitting direction of the light source body (the configuration of the cylindrical lens 133 is removed from FIG. 2 ), The spot lighting device (SLD) for detection of (ii) is a collimator lens arranged in front of the light emitting direction of the light source body (the same structure as in Fig. 3), and the spot lighting device (LED) for detection of (iii) is The collimating lens and the lenticular lens are arranged in front of the light emitting direction of the light source body.

As shown in Fig. 4, when the light source body is configured so that the laser light emitted by the semiconductor laser is directly emitted (LD), it can be confirmed that the directivity angle at which the relative radiation intensity reaches 50% or more of the peak value is about ±5° within. In addition, when the light source body is constructed so that the phosphor is irradiated with laser light and the secondary light generated by excitation is emitted (SLD), it has been confirmed that the directivity angle is within about ±3.5°.

＜Simulation of uniformity of irradiance＞ Next, using the concentrating illumination device for detection of the second embodiment, simulated conditions on the surface of the workpiece W when the optical magnification of the camera lens 22 having an object-side telecentric optical system is changed (2 times, 4 times) The results of uniformity of irradiance are shown in Fig.5. In this simulation, the sensor size of the imaging element 21a of the camera body 21 for shooting is set to be equivalent to 2/3 inch.

As shown in FIG. 5 , from the simulation results, it can be confirmed that the uniformity of the irradiance on the workpiece W surface is good regardless of the optical magnification of 2x or 4x. In particular, it has been confirmed that the higher the optical magnification is, the more the uniformity of the irradiance on the workpiece W surface can be improved.

＜Other Embodiments＞ In addition, this invention is not limited to the said embodiment.

For example, in the above-mentioned first embodiment, although the optical system 13 is provided with both the speckle remover 132 and the light diffusion surface formed on the light exit surface 1s as the light diffusion part, only one of them may be provided, or neither may be provided. Light diffusion part. In addition, the light-diffusing part may be, for example, a light-diffusing member such as a diffusion plate or a phosphor.

In addition, in the above-mentioned second embodiment, although the light source body 12 is configured so that the phosphor 12b is irradiated with laser light from the plurality of semiconductor lasers 12a, it is not limited to this. The light source body 12 of other embodiments may also be configured to include only one semiconductor laser 12a, and the phosphor 12b may be excited by the one semiconductor laser 12a.

Also, in each of the above-mentioned embodiments, the etendue of the light source body 12 and the etendue at each position of the optical system 13 are configured to be 1 mm ² ·sr or less, but the present invention is not limited thereto. In other embodiments, the etendue at each position of the light source body 12 and the optical system 13 may exceed 1 mm ² ·sr.

In addition, the present invention is not limited to the above-mentioned embodiments; various modifications can be made without departing from the scope of the gist. [Industrial availability]

According to the above-mentioned detection system of the present invention, the detection system is a detection system with a high-magnification object-side telecentric optical system with a coaxial epi-projection structure, which can improve the brightness when shooting.

1: Concentrating lighting device for detection 1s: Light exit surface 11: Lighting housing 12: Light source body 12a: Semiconductor laser 12b: Phosphor 13: Optical system 13f: Focus position 100: Detection system 111: barrel part 112: terminal part 131: Collimating lens 132: Light diffusion element (spot eliminator) 133: Cylindrical lens 2: Photographic device 21: Camera body 21a: Photographic components 22: Camera lens (telecentric lens) 221: Lens housing 22a: aperture aperture 22f: focus position 23: Coaxial shooting part 231: Lighting Installation Department 231a: Lighting installation port 232: half mirror C1, C2: optical axis S: inner space W: Workpiece

[FIG. 1] A diagram schematically showing the configuration of the detection system of the first embodiment and the second embodiment. [ Fig. 2] Fig. 2 is a diagram schematically showing the configuration of the spotlight illumination device for detection according to the first embodiment. [ Fig. 3] Fig. 3 is a diagram schematically showing the configuration of a spotlight illuminating device for detection according to a second embodiment. [ Fig. 4 ] A diagram showing simulation results of light distribution characteristics of a plurality of types of detection spotlight illumination devices with different configurations of light source bodies. [ Fig. 5 ] (a) and (b) are graphs showing simulation results of uniformity of irradiance of the spotlight illumination device for detection according to the second embodiment.

1: Concentrating lighting device for detection

1s: Light exit surface

11: Lighting housing

12: Light source body

12a: Semiconductor laser

13: Optical system

13f: Focus position

111: barrel part

112: terminal part

131: Collimating lens

132: Light diffusion element (spot eliminator)

133: Cylindrical lens

C1: optical axis

Claims (7)

A detection system comprising: A spotlight illuminating device for detection has a light source body and a light emitting surface that emits light emitted by the light source body as detection light; and A photographic device with an object-side telecentric optical system for photographing workpieces; The detection system is configured such that the detection light emitted from the light emitting surface is irradiated on the workpiece from the coaxial axis with the optical axis of the photographing device; The light source body is formed by using a semiconductor laser. As the detection system of claim 1, wherein, The light source body is configured to directly emit the laser light emitted by the semiconductor laser; The spotlight illuminating device for detection has a light diffuser that diffuses the laser light emitted from the light source body. As the detection system of claim 1, wherein, The light source body includes the semiconductor laser and a phosphor, and is configured to irradiate the phosphor with laser light emitted by the semiconductor laser to excite the phosphor to emit secondary light. The inspection system according to Claim 1, wherein the etendue of the light source body is 1 mm ² ·sr or less. As the detection system of claim 1, wherein, The direction angle of the detection light emitted from the light emitting surface is within ±5°. As the detection system of claim 1, wherein, The optical magnification of the object-side telecentric optical system is more than 2 times. A concentrating lighting device for detection, used together with an imaging device having an object-side telecentric optical system for photographing a workpiece, the concentrating lighting device for detection includes: a light source body, and emitting light emitted by the light source body as detection light the light exit surface; The light source system is composed of semiconductor lasers.

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