Light source device and observation system

Abstract

Provided is a light source device for irradiating a liquid-including object under measurement with measurement light, the light source device comprising: a light source unit for outputting light including visible light; a phase delay unit for delaying the phase of at least some of inputted light, and outputting light in which the phase of the inputted light is made non-uniform; a first polarization plate for passing light that has a presscribed polarization direction, from among the inputted light; and an output unit for outputting, toward the object under measurement as the measurement light, the light that has been outputted by the light source unit and has passed through the phase delay unit and the first polarization plate.

Description

Light source and observation system

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

[0002] The state of a liquid, an object in the liquid, an object or scene seen through the liquid, etc. may be observed using the naked eye, an imaging device, a microscope, etc. However, if bubbles or the like occur in the liquid, it becomes difficult to observe the object to be observed, so image processing or the like has been used to detect the bubbles and display their presence, or an operator has tried to remove the bubbles by replacing the liquid (see, for example, Patent Document 1).

[0003] International Publication No. 2018 / 070049

[0004] To remove bubbles that occur in a liquid, it is possible to replace the liquid or apply ultrasonic waves, but these methods are time-consuming and costly, and it can take a long time to remove the bubbles, or the bubbles may not be completely removed and remain, making it difficult to easily observe the object containing the liquid.

[0005] The present invention has been made in consideration of these points, and aims to make it possible to easily observe an observation object containing a liquid even if bubbles occur in the liquid.

[0006] In a first aspect of the present invention, there is provided a light source device for irradiating a measurement light onto a measurement object containing a liquid, the light source device comprising: a light source unit that outputs light including visible light; a phase delay unit that delays the phase of at least a portion of the input light to output the input light with an uneven phase; a first polarizing plate that passes light of a predetermined polarization direction among the input light; and an output unit that outputs the light output by the light source unit and that has passed through the phase delay unit and the first polarizing plate as the measurement light toward the measurement object.

[0007] The phase delay unit may include an interference glass that transmits or reflects at least a part of the light output from the light source unit. A plurality of the interference glasses may be arranged in a direction perpendicular to an optical axis direction in which the light source unit outputs the light.

[0008] The phase delay unit may include a total reflection mirror that reflects the input light to the output unit, and a half mirror that is provided between the light source unit and the total reflection mirror and that allows a portion of the input light to pass through the total reflection mirror while reflecting the remaining portion of the input light to the output unit.

[0009] The phase delay unit may include a λ / 2 phase plate or a λ / 4 phase plate between the light source unit and the first polarizer. The light source device may further include a 0-degree phase plate between the phase delay unit and the first polarizer.

[0010] The light source device may further include a color filter that passes light having a wavelength in the range of 560 nm to 570 nm out of the light output from the light source section.

[0011] In a second aspect of the present invention, there is provided an observation system for observing the object to be measured, comprising: the light source device of the first aspect, which outputs the measurement light toward the object to be measured; an imaging device having a second polarizing plate that transmits light in a polarization direction that is passed by the first polarizing plate and which images the object to be measured via the second polarizing plate; an illumination angle changing device that moves the light source device in a plane parallel to a first optical axis of the measurement light that the measurement light irradiates the object to be measured and a second optical axis that extends from the object to the imaging device, to change the illumination angle formed by the first optical axis and the second optical axis; and a control device that controls the illumination angle changing device to adjust the illumination angle to a predetermined angle.

[0012] The control device may adjust the irradiation angle based on the image captured by the imaging device. The control device may have a reception unit that receives feature information indicating features of the measurement object, and may adjust the irradiation angle based on the feature information received by the reception unit.

[0013] The receiving unit may receive the characteristic information indicating at least one of a size of bubbles contained in the liquid and a viscosity of the liquid. The control device may control the light source device based on the characteristic information to change the intensity of light output from the light source unit.

[0014] The control device may input captured image data generated by the imaging device capturing an image of the object to be measured into a machine learning model, and may set the angle output from the machine learning model as the predetermined angle.

[0015] According to the present invention, it is possible to easily observe an observation object containing a liquid even if bubbles occur in the liquid.

[0016] 1 shows an example of the configuration of an observation system S according to this embodiment; FIG. 2 shows an example of the configuration of a light source device 10 according to this embodiment; FIG. 3 shows an example of an interference glass 71 according to this embodiment; FIG. 4 shows a first example of observation results of the observation system S according to this embodiment; and FIG. 5 shows a second example of observation results of the observation system S according to this embodiment.

[0017] <Configuration Example of Observation System S> Fig. 1 shows a configuration example of an observation system S according to this embodiment. In Fig. 1, three orthogonal axes are defined as the X-axis, Y-axis, and Z-axis. The observation system S is a system for observing a measurement object T containing a liquid. The measurement object T is, for example, a liquid sealed in a container. The measurement object T may also be an object in the liquid, an object visible through the liquid, an object provided at the bottom of a container visible through the liquid, etc. The container may be made of glass, resin, plastic, etc.

[0018] In this embodiment, an example will be described in which the measurement object T is a liquid contained in a cylindrical container. For example, it is assumed that there is a case in which it is necessary to observe the liquid to observe the presence or absence of minute foreign matter floating in the liquid. The observation system S makes it possible to easily observe the observation object T even if bubbles occur in the liquid. The observation system S includes a light source device 10, an imaging device 20, an irradiation angle changing device 30, and a control device 40.

[0019] The light source device 10 outputs measurement light toward the measurement object T. FIG. 1 shows an example in which the light source device 10 irradiates the measurement light toward the measurement object T, which is a container containing a liquid. The measurement light indicated by the dashed line extending from the light source device 10 is linearly polarized light whose polarization direction is aligned with a predetermined direction. The polarization direction of the linearly polarized light is adjusted so that the light that enters the liquid and is reflected from the liquid and heads toward the imaging device 20 is p-polarized. In the example of FIG. 1, the polarization direction of the measurement light is parallel to the XY plane (plane of incidence). Details of such a light source device 10 will be described later.

[0020] The imaging device 20 captures an image of the measurement object T. The imaging device 20 is a camera that captures still images or videos. The imaging device 20 captures an image of the measurement object T by receiving measurement light reflected from the measurement object T. The imaging device 20 has a second polarizing plate 21, and it is desirable to capture an image of the measurement object T through the second polarizing plate 21. As will be described later, the light source device 10 also has a polarizing plate, so in the following description, the polarizing plate of the light source device 10 will be referred to as the first polarizing plate 83, and the polarizing plate of the imaging device 20 will be referred to as the second polarizing plate 21. The second polarizing plate 21 is arranged so that the polarization direction coincides with the polarization direction of the measurement light.

[0021] The irradiation angle changing device 30 changes the irradiation angle at which the light source device 10 irradiates the measurement object T with the measurement light. The irradiation angle changing device 30 has an actuator or the like for moving the light source device 10. The irradiation angle changing device 30 causes the actuator to move the light source device 10 so as to change the irradiation angle at which the measurement light irradiates the measurement object T while maintaining the polarization direction of the measurement light parallel to the incident plane.

[0022] The irradiation angle of the light source device 10 is the angle formed by a first optical axis of the measurement light irradiated onto the measurement object T and a second optical axis extending from the measurement object T toward the imaging device 20, in a plane parallel to the first optical axis and the second optical axis. In Fig. 1, the irradiation angle is indicated as φ. The irradiation angle changing device 30 changes the irradiation angle φ of the light source device 10 by moving the light source device 10 in an arc about a predetermined point while the irradiation direction of the light source device 10 remains facing the measurement object T.

[0023] The illumination angle change device 30 is configured to be able to change the illumination angle φ, for example, in the range from 0 degrees to 90 degrees. Fig. 1 shows, with a solid line, the light source device 10 when the illumination angle change device 30 sets the illumination angle φ to 90 degrees. In this case, the first optical axis is parallel to the X axis, and the second optical axis is parallel to the Y axis. Fig. 1 also shows, with a dotted line, the light source device 10 when the illumination angle φ is set to 0 degrees. In this case, the first optical axis and the second optical axis are parallel to the Y axis.

[0024] The control device 40 controls the irradiation angle change device 30 to adjust the irradiation angle φ to a predetermined angle. The predetermined angle is the Brewster angle. The Brewster angle is the angle of incidence at which the reflectance of p-polarized light becomes zero when light is incident on the interface between materials with different refractive indices. For example, even when measurement light is incident on the interface between a liquid and an air bubble, by converting the measurement light to p-polarized light and setting the angle of incidence of the measurement light to the Brewster angle, the amount of light reflected from the air bubble toward the imaging device 20 can ideally be reduced to zero.

[0025] The control device 40 controls the irradiation angle change device 30, for example, by supplying a drive signal to an actuator of the irradiation angle change device 30. The control device 40 may control the imaging device 20 to cause the imaging device 20 to capture an image. The control device 40 may acquire the image captured by the imaging device 20. The control device 40 is, for example, a server or a PC. The control device 40 includes a storage unit 41, a reception unit 42, and a control unit 43.

[0026] The storage unit 41 is a storage medium including a read-only memory (ROM) and a random access memory (RAM). The storage unit 41 may also include a large-capacity storage device such as a hard disk drive (HDD) and / or a solid state drive (SSD). For example, when a CPU or the like functions as the control unit 43, the storage unit 41 may store information such as an operating system (OS) that causes the CPU to function, programs, etc.

[0027] The storage unit 41 may also store various information including a database to be referenced when the program is executed. The storage unit 41 may store information such as the irradiation angle φ and the measurement target T. The storage unit 41 stores, for example, information such as the refractive index of various liquids and the Brewster angle corresponding to various liquids.

[0028] The reception unit 42 receives various information. For example, the reception unit 42 receives user input information input from an input device or the like. The user input information is, for example, the irradiation angle φ, information on the measurement object T, etc. The reception unit 42 may receive the irradiation angle φ, information on the measurement object T, etc. from a server, PC, database, etc. connected to the network via a communication unit or the like.

[0029] The control unit 43 generates control signals, drive signals, etc. for controlling each unit of the observation system S. For example, the control unit 43 generates a drive signal for setting the irradiation angle φ to the Brewster angle and transmits it to the irradiation angle changing device 30. Furthermore, when the reception unit 42 receives information on the angle at which irradiation should be performed, the control unit 43 generates a drive signal for setting the irradiation angle of the light source device 10 to the received angle and transmits it to the irradiation angle changing device 30. The reception unit 42 and the control unit 43 are, for example, a CPU (Central Processing Unit). The CPU functions as the reception unit 42 and the control unit 43 by executing a program stored in the storage unit 41.

[0030] In the observation system S described above, a liquid containing a measurement object T is irradiated with measurement light from a light source device 10 at an irradiation angle φ, and the image capture device 20 captures the light reflected from the liquid to observe the measurement object T. Because the measurement light is p-polarized light, even if bubbles occur in the liquid, the amount of light reflected by the bubbles and directed toward the image capture device 20 can be reduced compared to s-polarized light. By making the irradiation angle φ of the measurement light approximately equal to the Brewster's angle, ideally, even if bubbles occur in the liquid, the amount of light reflected from the bubbles directed toward the image capture device 20 can be reduced to zero, preventing the bubbles from being captured in the captured image (removing the bubbles).

[0031] However, even if p-polarized light is actually irradiated onto a liquid at the Brewster angle, it is difficult to reduce the light reflected from the bubbles and remove the bubbles from the captured image. Here, the ideal state in which the reflected light of p-polarized light is zero is considered to be a state in which the measurement light is incident at a phase that provides an ideal electric field strength (magnetic field strength) at the interface between the liquid and the bubbles, so that the interference effect of the light in the liquid and the interference effect of the light in the bubbles are balanced.

[0032] However, because the size and position of the actual bubbles vary, the phase of the measurement light at the interface between the liquid and the bubbles deviates from the ideal state. In this case, the balance between the interference effect of light in the liquid and the interference effect of light in the bubbles is lost at the interface between the liquid and the bubbles, so it is thought that even if the irradiation angle φ becomes the Brewster angle, the reflected light of p-polarized light cannot be sufficiently reduced.

[0033] The inventors discovered that deliberately making the phase of the measurement light non-uniform can sufficiently reduce the reflected light of p-polarized light and approach ideal reflection characteristics. Making the phase of the measurement light non-uniform results in measurement light with a phase distribution across multiple phase values ​​being incident on the interface between the liquid and the bubbles. This averages out the balance between the interference effect of light in the liquid and the interference effect of light in the bubbles, making it possible to approach ideal reflection characteristics even when the bubbles are of different sizes and positions.

[0034] In other words, the inventors discovered that even if bubbles occur in the liquid, by making the phase of the measurement light non-uniform and setting the irradiation angle φ of the observation system S to the Brewster angle, it is possible to output an image from which the bubbles have been removed. Therefore, the light source device 10 that outputs such measurement light will be described below.

[0035] 2 shows an example of the configuration of the light source device 10 according to this embodiment. The light source device 10 is a light source for irradiating the measurement object T with measurement light. The light source device 10 includes a base pedestal 11 that houses an optical system, and a cover unit 12. The light source device 10 outputs measurement light from an output unit 13 formed in the cover unit 12. The light source device 10 includes, as the optical system, a light source unit 60, a phase delay unit 70, a color filter 81, a second phase plate 82, a first polarizing plate 83, and an AR film 84.

[0036] The light source unit 60 outputs light including visible light. The light source unit 60 has an LED substrate 61, a heat sink 62, and a diffusion lens 63. An LED is mounted on the LED substrate 61. Alternatively, the light source unit 60 may be equipped with a laser diode or the like, but it is preferable to mount an LED with poor coherency (out of phase). Furthermore, the light output by the LED may have some bias in the polarization direction, but is preferably unpolarized light.

[0037] The heat sink 62 dissipates heat generated by the LED. Note that if the heat dissipation of the LED is sufficiently small, the heat sink 62 may not be necessary. The diffusion lens 63 diffuses the light output from the LED. It is desirable that the diffusion lens 63 diffuses the light output from the LED so that the light reaches most of the phase delay unit 70. Furthermore, it is desirable that at least the surfaces of the base pedestal 11 and the cover unit 12 facing the optical system are mirror-finished so that the diffused light is further diffused inside the light source device 10.

[0038] The phase delay unit 70 delays the phase of at least a portion of the input light to output the input light with a non-uniform phase. The phase delay unit 70 includes an interference glass 71, a first phase plate 72, a half mirror 73, a total reflection mirror 74, and a mirror angle adjuster 75.

[0039] The interference glass 71 is a plate-shaped glass that transmits or reflects at least a portion of the light output by the light source unit 60. Fig. 3 shows an example of the interference glass 71 according to this embodiment. For example, the interference glass 71 reflects a portion of the light diffused and output by the light source unit 60 at a first surface 91, and transmits the remaining portion from the first surface 91 into the interior of the interference glass 71. Furthermore, the interference glass 71 outputs a portion of the light transmitted into the interior of the interference glass 71 to the outside from a second surface 92 opposite the first surface 91, and reflects the remaining portion at the second surface 92 and transmits the remaining portion from the second surface 92 into the interior of the interference glass 71.

[0040] The interference glass 71 outputs a portion of the light reflected by the second surface 92 to the outside from the first surface 91 of the interference glass 71, and reflects the remaining portion of the light by the first surface 91 and transmits it from the first surface 91 back into the interference glass 71. In this way, the phase of the light output after repeated reflections by the first surface 91 and the second surface 92 of the interference glass 71 is delayed from the phase of the light that has passed through the interference glass 71, so the interference glass 71 functions as a delay element that makes the phase of the input light more non-uniform. Note that while FIG. 3 simplifies the representation of the light output by the light source 60 as a single light ray, it goes without saying that in reality, the light source 60 outputs multiple light beams at various angles, and multiple light beams enter the interference glass 71.

[0041] The phase delay unit 70 preferably includes a plurality of interference glasses 71. The plurality of interference glasses 71 can form a plurality of complex optical paths, and therefore can impart various phase differences to the light before outputting it. Fig. 2 shows an example in which a plurality of interference glasses 71 are arranged in a direction perpendicular to the optical axis direction along which the light source unit 60 outputs light.

[0042] Since each interference glass 71 is arranged parallel to the optical axis, it is possible to form a complex optical path of the light input from the light source unit 60 while reducing the amount of light reflected in the direction of the light source unit 60. As a result, the multiple interference glasses 71 can output light with non-uniform phases while reducing light loss.

[0043] The first phase plate 72 is disposed between the light source unit 60 and the first polarizing plate 83. The first phase plate 72 is a λ / 2 phase plate or a λ / 4 phase plate. The light output from the light source unit 60 is not linearly polarized. Furthermore, since the light output from the light source unit 60 is diffused by the diffusion lens 63, it enters the first phase plate 72 at various angles of incidence. The first phase plate 72 then imparts to the passing light different phase delays corresponding to the polarization direction and angle of incidence of the passing light. In other words, the first phase plate 72 functions as a delay element that makes the phase of the input light more non-uniform.

[0044] The half mirror 73 is provided between the light source unit 60 and the total reflection mirror 74, and allows a portion of the input light to pass through the total reflection mirror 74 while reflecting the remaining portion of the input light toward the output unit 13 of the cover unit 12. The total reflection mirror 74 reflects the input light that has passed through the half mirror 73 toward the output unit 13. The mirror angle adjustment unit 75 is a fixing member, a support, or the like for fixing the half mirror 73 and the total reflection mirror 74. The mirror angle adjustment unit 75 is attached to a base pedestal.

[0045] The phase of light that passes through the half mirror 73, is reflected by the total reflection mirror 74, and then reaches the output unit 13 is delayed compared to the phase of light that is reflected by the half mirror 73 and reaches the output unit 13. Furthermore, the half mirror 73 passes a portion of the reflected light reflected by the total reflection mirror 74 toward the output unit 13, and reflects the remaining portion of the reflected light back to the total reflection mirror 74. The total reflection mirror 74 reflects the light that was reflected by the half mirror 73 and input toward the output unit 13.

[0046] In this way, the phase of the light that passes through the half mirror 73 and is repeatedly reflected by the half mirror 73 and the total reflection mirror 74 before reaching the output unit 13 is delayed from the phase of the light that is reflected by the half mirror 73 and reaches the output unit 13. Therefore, the half mirror 73 and the total reflection mirror 74 function as delay elements that make the phase of the input light more non-uniform.

[0047] As described above, the phase delay unit 70 uses a plurality of delay elements to make the phase of input light non-uniform and then output the light. The phase delay unit 70 may be configured to include at least one delay element selected from one or more interference glasses 71, a first phase plate 72, a half mirror 73, and a total reflection mirror 74. The phase delay unit 70 may also be configured to include a plurality of identical delay elements.

[0048] The color filter 81 is a filter that passes light having a wavelength in the range of 560 nm to 570 nm from the light output by the light source unit. The color filter 81 is, for example, a band-pass filter. The color filter 81 may also be a high-pass filter or a low-pass filter. Yellow, orange, and the like are known to be colors that are easily recognized by an observer when used as a single color background. Therefore, by using the color filter 81 to pass light in the wavelength range of 560 nm to 570 nm, the measurement light can be made into a color that is easily recognized.

[0049] The second phase plate 82 is provided between the phase delay unit 70 and the first polarizing plate 83. The second phase plate 82 is a 0-degree phase plate. The 0-degree phase plate has the function of aligning the polarization direction. The second phase plate 82 increases the amount of light passing through the first polarizing plate 83, thereby enabling the measurement light to be output efficiently.

[0050] The first polarizing plate 83 transmits light of a predetermined polarization direction out of the input light. As described in FIG. 1 , the polarization direction of the first polarizing plate 83 is adjusted so that the polarization direction of the measurement light with respect to the measurement object T becomes p-polarized light. Alternatively, the position of the light source device 10 may be adjusted so that the polarization direction of the measurement light with respect to the measurement object T becomes p-polarized light.

[0051] The AR film 84 is an anti-reflection film for reducing reflected light and the like that enters the output unit 13. The AR film 84 may be a substrate on which an anti-reflection coating is formed, an anti-reflection filter, or the like.

[0052] In the light source device 10 described above, the light output from the light source unit 60 passes through the phase delay unit 70 and the first polarizing plate 83, making the phase non-uniform, and the light with a consistent polarization direction can be output as measurement light from the output unit 13 toward the measurement object T. The phase delay unit 70 can non-uniformly delay the phase of light without using any special optical elements, making it easy to configure the light source device 10 that can observe the observation object T in a liquid while reducing costs. Observation results using an observation system S using such a light source device 10 will now be described.

[0053] <Example of Observation Results of Observation System S> Figure 4 shows a first example of observation results of the observation system S according to this embodiment. Figure 4 shows an example of the result of the imaging device 20 capturing an image of the observation target T when bubbles are generated in the liquid and the irradiation angle φ of the measurement light is not the Brewster angle. Figure 4 shows that, because multiple bubbles are generated in the liquid, it is difficult to observe foreign matter floating in the liquid or to determine whether or not foreign matter is present in the liquid.

[0054] Fig. 5 shows a second example of the observation results of the observation system S according to this embodiment. Fig. 5 shows an example of the result of the imaging device 20 capturing an image of the observation target T when bubbles are generated in the liquid and the irradiation angle φ of the measurement light is set to the Brewster angle. Fig. 5 shows that, even though multiple bubbles are generated in the liquid, the bubbles are successfully removed from the captured image.

[0055] Therefore, the observation system S can easily observe foreign matter floating in the liquid even if bubbles occur in the liquid. In the example of Figure 5, it is easy to determine that no foreign matter is present in the liquid. In other words, it can be seen that the observation system S according to this embodiment can easily observe the observation target T containing liquid even if bubbles occur in the liquid.

[0056] <Other Configurations> The observation system S according to the present embodiment has been described above as an example in which the observation target T is observed by irradiating the measurement light from the light source device 10 onto the observation target T, but the present invention is not limited to this. The observation system S may adjust the irradiation angle φ of the measurement light from the light source device 10 based on the observation results.

[0057] 4 and 5, it is easy to determine from the observation image that the bubbles have disappeared, and therefore the observation system S can compare the observation images to adjust the irradiation angle φ of the measurement light from the light source device 10. In this case, the control device 40 described in FIG. 1 adjusts the irradiation angle φ based on the image captured by the imaging device 20.

[0058] For example, the control device 40 controls the irradiation angle changing device 30 so that the irradiation angle φ of the measurement light becomes a predetermined initial angle φ0. The initial angle φ0 is, for example, 0 degrees. Then, the control device 40 controls the imaging device 20 to capture an image when the measurement light is irradiated onto the observation target T at the irradiation angle φ0, and acquires the captured image as the 0th captured image.

[0059] Next, the control device 40 controls the irradiation angle changing device 30 so that the irradiation angle φ of the measurement light becomes a predetermined first angle φ1. The first angle φ1 is, for example, 1 degree, 0.5 degrees, 0.1 degrees, etc. Then, the control device 40 controls the imaging device 20 to capture an image when the measurement light is irradiated onto the observation target T at the irradiation angle φ1, and acquires the captured image as a first captured image.

[0060] Next, the control device 40 controls the irradiation angle changing device 30 so that the irradiation angle φ of the measurement light becomes a predetermined second angle φ2. The second angle φ2 is, for example, twice the first angle φ1. The control device 40 then controls the imaging device 20 to capture an image when the measurement light is irradiated onto the observation target T at the irradiation angle φ2, and acquires the captured image as a second captured image.

[0061] In this way, the control device 40 captures images while changing the irradiation angle φ of the measurement light by a predetermined first angle φ1, and repeats the operation of changing the irradiation angle φ and the image capture operation until the irradiation angle φ reaches the end angle φz. The control device 40 then compares the acquired captured images to identify the captured image with the greatest reduction in bubbles. The control device 40 stores the irradiation angle φ when the identified captured image was captured in the memory unit 41 as the measurement irradiation angle φm (the predetermined angle described in FIG. 1 ). Alternatively, the control device 40 may fix the irradiation angle φ of the measurement light to the measurement irradiation angle φm.

[0062] The control device 40 may change the irradiation angle φ until the irradiation angle φ becomes the end angle φz, and then perform the image comparison of the captured images, or alternatively, may perform the image comparison every time the irradiation angle φ is changed. Information on the initial angle φ0, the end angle φz, and the first angle φ1 may be stored in the storage unit 41, or alternatively, may be included in the information received by the receiving unit 42.

[0063] Alternatively, the measurement irradiation angle φm may be stored in the storage unit 41, or may be included in the information received by the receiving unit 42. In this case, the control device 40 can quickly acquire an image with reduced bubbles by adjusting the irradiation angle φ of the measurement light to the measurement irradiation angle φm.

[0064] The appropriate irradiation angle φm for reducing bubbles generated in the liquid may vary depending on the size of the bubbles, the type of liquid, the material of the container containing the liquid, etc. Therefore, the receiving unit 42 may receive characteristic information indicating the characteristics of the measurement target T. The characteristic information indicates, for example, at least one of the size of bubbles contained in the liquid and the viscosity of the liquid. The characteristic information may include the type of liquid, the refractive index of the liquid, etc.

[0065] The control device 40 adjusts the irradiation angle φ based on the feature information received by the receiving unit 42. For example, when at least one piece of information among the initial angle φ0, the end angle φz, and the first angle φ1 is associated with the feature information, the control device 40 specifies the measurement irradiation angle φm using the information corresponding to the feature information. It is assumed that the information associated with the feature information, such as the initial angle φ0, the end angle φz, and the first angle φ1, is stored in advance in the storage unit 41.

[0066] Alternatively, the characteristic information may be associated with an irradiation angle φm. In this case, information on the irradiation angle φm associated with the characteristic information is stored in advance in the storage unit 41. The control device 40 reads out the irradiation angle φm corresponding to the characteristic information from the storage unit 41 and adjusts the irradiation angle φ of the measurement light to the measurement irradiation angle φm, thereby enabling the capture of an image with reduced bubbles to be quickly obtained.

[0067] The observation system S according to the present embodiment has been described above as an example in which the irradiation angle φ of the measurement light output by the light source device 10 is adjusted, but the present invention is not limited to this. Alternatively, or in addition, the observation system S may adjust the intensity of the measurement light from the light source device 10. For example, if the liquid has poor transparency, it may be difficult to observe an object in the liquid unless the intensity of the measurement light is appropriately adjusted.

[0068] Therefore, the control device 40 controls the light source device 10 based on the feature information received by the receiving unit 42 to change the intensity of light output by the light source unit 60. In this case, it is assumed that information on the appropriate light intensity of the light source unit 60 associated with the feature information is stored in advance in the storage unit 41. The control device 40 reads out the information on the light intensity of the light source unit 60 corresponding to the feature information from the storage unit 41 and adjusts the light intensity of the light source unit 60, thereby enabling the control device 40 to quickly acquire an image with reduced bubbles.

[0069] The observation system S according to the present embodiment has been described above as an example in which the irradiation angle φ of the measurement light is adjusted by comparing multiple captured images, but the present invention is not limited to this. Alternatively, the observation system S may adjust the irradiation angle φ of the measurement light using machine learning. As shown in FIGS. 4 and 5 , it is easy to determine whether or not bubbles have disappeared from the observation images. Therefore, by using combinations of multiple observation images and corresponding irradiation angles as learning data for the machine learning model, the learning model can calculate a more appropriate irradiation angle φ.

[0070] For example, the control device 40 inputs the captured image data generated by the imaging device 20 capturing an image of the measurement target T into a machine learning model, and sets the angle output from the machine learning model as the measurement irradiation angle φm (the predetermined angle described in FIG. 1 ). This allows the control device 40 to quickly identify the measurement irradiation angle φm even without characteristic information of the observation target T.

[0071] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments.

[0072] REFERENCE SIGNS LIST 10 Light source device 11 Base pedestal 12 Cover section 13 Output section 20 Imaging device 21 Second polarizing plate 30 Irradiation angle changing device 40 Control device 41 Memory section 42 Reception section 43 Control section 60 Light source section 61 LED substrate 62 Heat sink 63 Diffusion lens 70 Phase delay section 71 Interference glass 72 First phase plate 73 Half mirror 74 Total reflection mirror 75 Mirror angle adjustment section 81 Color filter 82 Second phase plate 83 First polarizing plate 84 AR film 91 First surface 92 Second surface

Claims

1. A light source device for irradiating a measurement light onto a measurement object containing a liquid, comprising: a light source unit that outputs light including visible light; a phase delay unit that delays the phase of at least a portion of the input light to output the input light with an uneven phase; a first polarizing plate that passes light of a predetermined polarization direction among the input light; and an output unit that outputs the light output by the light source unit and that has passed through the phase delay unit and the first polarizing plate as the measurement light toward the measurement object.

2. The light source device according to claim 1, wherein the phase delay section has interference glass that transmits or reflects at least a portion of the light output by the light source section.

3. The light source device according to claim 2, wherein the interference glass is arranged in a plurality of rows in a direction perpendicular to the optical axis direction along which the light source section outputs light.

4. The light source device according to claim 1, wherein the phase delay section comprises: a total reflection mirror that reflects input light to the output section; and a half mirror that is provided between the light source section and the total reflection mirror and that allows a portion of the input light to pass through the total reflection mirror while reflecting the remaining portion of the input light to the output section.

5. The light source device according to claim 1, wherein the phase delay section has a λ / 2 phase plate or a λ / 4 phase plate between the light source section and the first polarizing plate.

6. The light source device according to claim 1, further comprising a 0-degree phase plate between the phase delay section and the first polarizing plate.

7. The light source device according to claim 1, further comprising a color filter that passes light having a wavelength in the range of 560 nm to 570 nm out of the light output from the light source section.

8. An observation system for observing the object to be measured, comprising: the light source device according to any one of claims 1 to 7, which outputs the measurement light toward the object to be measured; an imaging device having a second polarizing plate that passes light in the polarization direction that the first polarizing plate passes through, and which images the object to be measured via the second polarizing plate; an illumination angle changing device that moves the light source device in a plane parallel to a first optical axis of the measurement light that the measurement light irradiates the object to be measured and a second optical axis that extends from the object to the imaging device, to change the illumination angle formed by the first optical axis and the second optical axis; and a control device that controls the illumination angle changing device to adjust the illumination angle to a predetermined angle.

9. The observation system according to claim 8, wherein the control device adjusts the irradiation angle based on the image captured by the imaging device.

10. The observation system according to claim 8, wherein the control device has a reception unit that receives characteristic information indicating characteristics of the object to be measured, and adjusts the irradiation angle based on the characteristic information received by the reception unit.

11. The observation system according to claim 10, wherein the receiving unit receives the characteristic information indicating at least one of the size of bubbles contained in the liquid and the viscosity of the liquid.

12. The observation system according to claim 10, wherein the control device controls the light source device based on the characteristic information to change the intensity of the light output by the light source unit.

13. The observation system described in claim 8, wherein the control device inputs captured image data generated by the imaging device capturing an image of the object to be measured into a machine learning model, and sets the angle output from the machine learning model as the specified angle.

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