JP2019204756A - Luminaire - Google Patents

Abstract

To provide a luminaire such that up to a subject deep part can be clearly observed.SOLUTION: The present invention relates to a luminaire (100) which uses a semiconductor laser as a light source to radiate a subject, and the luminaire comprises: a plurality of light emission parts (30, 40) which emit a plurality of lights differing in wavelength band; a light emission control part (10) which controls respective light emission outputs of the plurality of light emission parts; and a mixing part (60) which mixes the outputs of the plurality of light emission parts to generate an output light. The light emission control part controls wavelengths and power densities of the respective light emission outputs of the plurality of light emission parts to obtain a reflected light from a deep part of a subject.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device including medical and industrial use.

  Conventionally, for example, a xenon light source is widely known as a light source used in an endoscope system for observing tissue in a body cavity. A xenon light source has high brightness and a very wide emission wavelength. For this reason, the xenon light source can be applied not only as a visible light source but also as a light source for fluorescent image observation, and is widely used by supporting each wavelength required in combination with an optical filter.

  In recent years, the brightness of LEDs has been increased, and LED light sources are widely used from consumer lighting to industrial applications such as flashlights, residential lighting and traffic lights. In addition to this, recently, LED light sources are also being used in the field of light sources such as experimental high-intensity light sources.

  Furthermore, recently, there is a light source using a semiconductor laser as a special application. A light source using such a semiconductor laser is a special application that takes advantage of laser light capable of emitting a specific wavelength. As a visible light source that emits stable and safe white light, a photoelectric that can replace a xenon light source is still under investigation.

  The xenon light source disclosed in Patent Document 1 uses a filter against heat rays. However, since the xenon light source according to Patent Document 1 uses an excitation light portion and includes a radiation intensity component having a wavelength of 700 to 800 nm, which is a part of the near infrared, it is not a complete measure as a visible light source. .

  Some recent LED light sources realize the visible light range with LEDs. However, natural light is reproduced.

JP 2009-140827 A

  When xenon illumination is used as the light source device, since it has a high luminance and a wide band, it is very advantageous from the viewpoint of observation, camera imaging in surgery, and the like. However, from the viewpoint of the subject, the operator, and the observer, xenon illumination includes many unnecessary wavelength band components such as near infrared light that is an unnecessary heat ray component and ultraviolet light components that have an adverse effect on the retina and skin. For this reason, xenon illumination is difficult to use for a long time. In addition, when using xenon illumination, special measures such as eyeglasses and heat ray countermeasures are required, and although the brightness is high, the advantages are not fully utilized.

  In addition, since xenon illumination has a wavelength characteristic close to that of sunlight, it is possible to reproduce natural brightness. However, xenon illumination is not suitable for observing necessary parts or characteristic parts of subjects required in the medical or industrial fields. Specifically, xenon illumination is special, for example, by irradiating only the required wavelength with the required power density and obtaining reflected light from the deep part of the subject to obtain a subject light image that could not be obtained in a wide band. The demand for the application could not be met.

  Furthermore, in the case of a light source used for fluorescent image observation in medical or industrial applications, there is a structure that transmits only a necessary wavelength with an optical filter using a wide band of xenon. However, since the light source having such a structure performs filtering from high brightness and wide band to narrow band, heat is generated in the filter portion, spectral characteristics are not stable, and light emission efficiency is poor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an illuminating device that can be observed clearly up to the deep part of a subject.

  An illuminating device according to the present invention is an illuminating device that irradiates a subject using a semiconductor laser as a light source. A light emission control unit for controlling, and a mixing unit for mixing the outputs of the plurality of light emitting units and generating output light, and the light emission control unit sets a wavelength and a power density for each light emission output of the plurality of light emitting units. The reflected light is controlled from the deep part of the subject.

  According to the present invention, a configuration is provided in which reflected light from the deep part of the subject can be obtained. As a result, it is possible to realize an illuminating device that allows clear observation up to the deep part of the subject.

It is a schematic block diagram of the illuminating device in Embodiment 1 of this invention. It is a spectral characteristic figure of the illuminating device in Embodiment 1 of this invention. It is a figure which shows an example of the light emission wavelength control characteristic by the temperature of the illuminating device which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the light emission intensity characteristic by the electric current of the illuminating device which concerns on Embodiment 1 of this invention. It is a detailed block diagram of the laser emission unit in the wavelength unit in the illuminating device which concerns on Embodiment 1 of this invention. FIG. 4 is a diagram illustrating the degree of penetration of light for each wavelength into a subject in the lighting apparatus according to Embodiment 1 of the present invention. It is explanatory drawing which shows the comparison result of the to-be-observed image by the illuminating device in Embodiment 1 of this invention, and a xenon illumination.

  Hereinafter, preferred embodiments of a lighting device of the present invention will be described with reference to the drawings.

  Embodiment 1 FIG.

  FIG. 1 is a schematic block diagram of a lighting apparatus according to Embodiment 1 of the present invention. The illuminating device 100 which concerns on this Embodiment 1 shown in FIG. 1 has shown the example which used the semiconductor laser for the light emitting element of the light source. Specifically, the illumination device 100 includes a laser emission control unit 10, a laser power supply unit 20, a plurality of laser driving units 30, a plurality of laser emission units 40, a plurality of optical fibers 50, and a rod integrator 60 for mixing laser beams. It is comprised including.

  FIG. 1 illustrates a case where the plurality of laser driving units 30 are configured by four laser driving units 30 (1) to 30 (4). Further, FIG. 1 illustrates a case where the plurality of laser light emitting units 40 are configured by four laser light emitting units 40 (1) to 40 (4). The laser driving units 30 (1) to 30 (4) and the laser light emitting units 40 (1) to 40 (4) correspond one-to-one as shown in FIG. That is, FIG. 1 illustrates a case where four sets of laser light emitting units each including one laser driving unit 30 and one laser light emitting unit 40 are provided.

  Note that the laser driving unit 30 and the laser light emitting unit 40 shown in FIG. 5 can be combined into one light emitting unit to constitute a laser light emitting unit.

  FIG. 2 is a spectral characteristic diagram of illumination apparatus 100 according to Embodiment 1 of the present invention. The outputs of the laser emission units 40 (1) to 40 (4) have laser spectral characteristics 70 (1) to 70 (4), respectively.

  The spectral characteristics 70 of the laser light emitting units 40 (1) to 40 (3) correspond to the spectral characteristics 70 (1) to 70 (3), respectively. Therefore, the light emission by the laser light emitting units 40 (1) to 40 (3) is in the range of 400 to 700 nm of the visible region 71, and the laser light emitting units 40 (1) to 40 (3) are used as normal visible light sources. Operate.

  On the other hand, the laser light emitting unit 40 (4) has a wavelength of 780 nm having a spectral characteristic 70 (4), for example, and emits light having a necessary wavelength according to the application. Thus, the laser light emission part 40 in this Embodiment 1 is the structure which light-emits one wavelength band with one light emission part.

  FIG. 3 is a diagram illustrating an example of the emission wavelength control characteristic depending on the temperature of the lighting apparatus according to Embodiment 1 of the present invention. The example of the emission wavelength control characteristic by the temperature Ta shown in FIG. 3 shows an example of the wavelength characteristic of the semiconductor laser. That is, the laser emission control unit 10 can control and limit the emission wavelength as a light source by using the emission wavelength control characteristic example 81 based on the temperature Ta.

  FIG. 4 is a diagram showing an example of the light emission intensity characteristic depending on the current of the lighting apparatus according to Embodiment 1 of the present invention. The example of the emission intensity control characteristic by the current shown in FIG. 4 shows an example of the emission characteristic of the semiconductor laser. That is, the laser light emission control unit 10 can detect the light emission state as the light source by using the light emission intensity characteristic example 82 by the forward current.

  FIG. 5 is a detailed block diagram of the laser light emitting unit in units of wavelengths in the illumination device according to Embodiment 1 of the present invention. The laser driving unit 30 includes a light emitting element driving circuit 31 and two detection circuits 32a and 32b.

  The laser light emitting unit 40 includes two light emitting elements 41a and 41b, a temperature sensor 42, and a cooling device 43. The light emitting element 41a is connected to the detection circuit 32a, and the light emitting element 41b is connected to the detection circuit 32b.

  The light emitting element 41a is optically connected to the optical fiber 51a, and the light emitting element 41b is optically connected to the optical fiber 51b. With such a configuration, light from the light emitting elements 41a and 41b is output as light source light via the respective optical fibers 51a and 51b.

  In the normal operation state of the light source, control by the laser light emission control unit 10 is performed so that the semiconductor laser on the light emitting element 41a side emits light. The light emitting element 41b is used as a spare when the light emitting element 41a deteriorates, and a specific usage will be described later.

  Next, the operation of the lighting apparatus according to the first embodiment will be described in detail with reference to FIGS. When the power is turned on, power is supplied from the laser power supply unit 20 to necessary parts such as the laser light emission control unit 10, and the lighting device 100 is operable as a light source.

  First, the laser emission control unit 10 supplies power to the laser driving unit 30 (1) and controls driving in order to emit the semiconductor laser of the laser emitting unit 40 (1).

  The laser light emitting unit 40 (1) emits light with a wavelength of 450 ± 2 nm by the rated power supply and temperature control by the laser spectral characteristic 70 (1) shown in FIG. The laser emission control unit 10 acquires the current detected by the detection circuit 32a shown in FIG. 5 in order to maintain the laser emission at 450 ± 2 nm. Further, the laser light emission control unit 10 performs drive control at the center C point between the current ranges A to B shown in the light emission intensity characteristic example 82 by the current of FIG.

  Here, the light emission of the semiconductor laser is accompanied by resonance by light, and a current equal to or higher than a certain threshold is required. The point A in FIG. 4 is the threshold current of the light emitting element 41a, and the laser light emission control unit 10 controls the light emission of the light emitting element 41a so as to be equal to or higher than the current at the point A in order to maintain light emission as described above. .

  Further, the laser emission control unit 10 performs temperature control in order to maintain laser emission at 450 ± 2 nm using the emission wavelength control characteristic example 81 by the temperature Ta in FIG. Specifically, the laser light emission control unit 10 performs temperature control so that the light emitting element 41a becomes 20 to 25 ° C. by the cooling device 43 based on the temperature detection result by the temperature sensor 42 shown in FIG.

  The emission wavelength of a semiconductor laser is determined by the physical properties of the device and its structure, but the wavelength during emission depends on the temperature. Therefore, in order to maintain the emission wavelength, temperature control is required in addition to emission control based on current. By such control, laser emission of 450 ± 2 nm is maintained. This wavelength is blue, and is later synthesized together with the red wavelength and the green wavelength to generate visible light.

  Further, the laser emission control unit 10 causes the laser emission units 40 (2), 40 (3), and 40 (4) to emit a semiconductor laser by the same control as the laser emission unit 40 (1) described above. The laser drive units 30 (2), 30 (3), and 30 (4) are supplied with power and controlled.

  The laser light emitting unit 40 (2) emits light with a wavelength of 550 ± 2 nm by the rated power supply and temperature control by the laser spectral characteristic 70 (2) shown in FIG. The laser light emitting unit 40 (3) emits light with a wavelength of 650 ± 2 nm by the rated power supply and temperature control by the laser spectral characteristic 70 (3) shown in FIG. Further, the laser light emitting unit 40 (4) emits light at a wavelength of 780 ± 2 nm by the rated power supply and temperature control by the laser spectral characteristic 70 (4) shown in FIG.

  In order to maintain each laser emission, the laser emission controller 10 detects the current by the detection circuit 32a, and at the center C point between the current ranges A to B shown in the emission intensity characteristic example 82 by the current of FIG. , Drive control.

  Here, the light emission of the semiconductor laser is accompanied by resonance due to light, and a current exceeding a certain threshold is required. The point A in FIG. 4 is the threshold current of the light emitting element 41a, and the laser light emission control unit 10 controls the light emission of the light emitting element 41a so as to be equal to or higher than the current at the point A in order to maintain light emission as described above. .

  Further, the laser emission control unit 10 performs temperature control in order to maintain the laser emission at each wavelength by using the emission wavelength control characteristic example 81 according to the temperature in FIG. Specifically, the laser light emission control unit 10 determines the temperature for each wavelength so that the light emitting element 43a becomes 20 to 25 ° C. by the cooling device 43 based on the temperature detection result by the temperature sensor 42 shown in FIG. Take control.

  As described above, by performing emission control and temperature control for each wavelength, laser emission of four wavelengths of 450 ± 2 nm, 550 ± 2 nm, 650 ± 2 nm, and 780 ± 2 nm is maintained. The three wavelengths of green at 550 ± 2 nm, red at 650 ± 2 nm, and blue at 450 ± 2 nm are combined together to generate visible light.

  These four wavelengths of light are condensed on a laser beam mixing rod integrator 60 via a laser optical fiber 50. The laser light is diffused by the rod integrator 60, so that the coherence and light condensing properties are suppressed, and the light output having the spectral characteristics shown in FIG.

  As described above, the light emitted from each laser emission unit 40 is transmitted from the laser light optical fiber 50 through the laser beam mixing rod integrator 60 for use in an external device that requires a light source. Output from the main body of the lighting device 100. The light output from the lighting device 100 is connected to an external device that requires light through a dedicated attachment so as to be used as efficiently as possible.

  As described above, the illumination device 100 according to the first embodiment has a configuration having four emission wavelengths as a light source. Furthermore, the lighting device 100 can selectively change the light emission pattern depending on the operation and purpose. For example, during operation as a normal visible light source, the laser emission control unit 10 emits light only from the laser emission units 40 (1), 40 (2), and 40 (3) and emits light from the laser emission unit 40 (4). Control is performed so that it does not occur.

  Further, the laser emission control unit 10 can emit only the wavelength necessary for fluorescence observation. For example, in the case of fluorescein, the laser light emission control unit 10 emits only a wavelength of 450 mn from the laser light emission unit 40 (1), thereby obtaining a fluorescent light image more efficiently than a broad characteristic LED or xenon. Can do.

  Further, the laser emission control unit 10 can infiltrate the light down to the surface of several millimeters of the subject by irradiating the living body with laser light at a power density in a safe area. As described above, by controlling the power density, reflected light or diffused light is generated not only from the subject surface but also from several millimeters behind the subject surface.

  For this reason, unlike a general light source, by using the illumination device 100 according to the first embodiment, it is possible to observe the subject more brightly, vividly and vividly. For example, consider the case where dry meat such as beef jerky is irradiated with light. In this case, in the xenon illumination, the surface reflection light is almost all, so that the dry state of the surface is emphasized.

  On the other hand, in the illumination device 100 according to the first embodiment, the color is developed from the back rather than the subject surface due to the influence of reflected light and diffused light that has penetrated several mm by laser illumination. For this reason, the beef jerky looks very clear, and depending on the irradiation conditions, the beef jerky may look like raw meat.

  FIG. 6 is a diagram showing the degree of penetration of light into the subject for each wavelength in the lighting apparatus according to Embodiment 1 of the present invention. The degree of light penetration varies depending on the wavelength, as shown in FIG. Each graph in FIG. 6 shows a blue graph 83, a green graph 84, and a red graph 85.

  In contrast to the blue graph 83, as the green graph 84 and the red graph 85 are obtained, there is a characteristic that the penetration degree increases as the wavelength becomes longer. Using this characteristic, the lighting device 100 uses a lower wavelength for a portion close to the subject surface, and uses a higher wavelength for a deeper portion, thereby making the subject clearer. It can be projected. Depending on the purpose of observation, only one wavelength may be used, or a plurality of wavelengths may be used in combination.

  In addition, when using a plurality of wavelengths, it is possible to further emphasize a portion to be observed in the subject by making a difference in power density and intensity of each wavelength. FIG. 7 is an explanatory diagram illustrating a comparison result of subject observation images obtained by the illumination device 100 according to Embodiment 1 of the present invention and xenon illumination.

  More specifically, a subject observation image 91 obtained by xenon illumination and a subject observation image 92 obtained by the illumination device 100 according to the first embodiment are shown in the upper part of FIG. Further, in the lower part of FIG. 7, direct light and reflected light or diffused light obtained based on the direct light in the illumination device according to the xenon illumination and the first embodiment are schematically described.

  It can be seen that the subject observation image 92 obtained by laser illumination by the illumination device 100 is an image that can be observed brightly and vividly with respect to the subject observation image 91 obtained by xenon illumination.

  That is, in the case of using xenon illumination, only the reflected light 94b with respect to the direct light 94a is observed, and the subject observation image 91 is obtained. On the other hand, when the laser illumination according to the first embodiment is used, reflected light or diffused light 93b with respect to the direct light 93a penetrating the subject is observed in addition to the reflected light 94b with respect to the direct light 94a. As a result, an image 92 is obtained.

  That is, the illumination device 100 according to the first embodiment can add three-dimensional reflected light by adding reflected light or diffused light 93b after penetrating into the subject to the reflected light 94b on the subject surface. . As a result, it is possible to obtain a subject observation image 92 that allows the subject to be observed brightly and vividly as a whole.

  Like the specific example mentioned above, the illuminating device 100 which concerns on this Embodiment 1 is equipped with the structure which can be made to light-emit a required light emission part suitably according to the operation objective. With such a configuration, it is possible to appropriately control the emission wavelength without generating unnecessary light such as an ultraviolet ray region harmful to eyes and skin, a near infrared ray region having an influence as heat rays, and the like. As a result, a light source with high accuracy and high efficiency can be realized by making it possible to selectively emit light in a wavelength band that is appropriately controlled.

  In addition, although only one light emitting element may be used for each wavelength, a configuration in which a plurality of light emitting elements 41 are provided in one laser light emitting unit 40 as illustrated in FIG. 5 may be employed. Needless to say, it can be done. In the normal state, the laser light emission control unit 10 causes the light emitting element 41a to emit light, but when the light emitting element 41a stops emitting light for some reason, it controls to switch to the light emitting element 41b.

  In order to perform such control, individual detection circuits 32a and 32b are provided for each of the light emitting elements 41a and 41b. Then, the light emitting element drive circuit 31 can determine that there is a high possibility that the light emission of the light emitting element 41a has stopped when the current detected by the detection circuit 32a is equal to or less than the point A of the threshold current characteristic example. Therefore, the light emitting element driving circuit 31 notifies the user that the life of the light emitting element 41a has come to some extent as a self-diagnosis based on this information.

  On the other hand, when the laser light emission control unit 10 receives a self-diagnosis result from the light emitting element drive circuit 31 informing that the light emitting element 41a has reached the end of its life, it performs switching control from the light emitting element 41a to the light emitting element 41b. Thus, the light emission as the light source can be continued.

  In addition, the light emitting element drive circuit 31 can also be performed based on the secular change of the electric current detected by 32 in the detection circuit as a self-diagnosis function. That is, the light emitting element drive circuit 31 determines that the light emission stop is near when the detected current gradually decreases during use of the lighting device 100, for example, when the light emitting element drive circuit 31 has dropped to a value slightly higher than the point A. As the life is approaching, an abnormality can be notified in advance.

  The light emission wavelength of the laser light emitting unit 40 may be any as long as it is a required wavelength. In other words, the laser emission unit 40 (1) does not need to have a wavelength of 450 nm, and may be 440 nm or 460 nm, for example, if it is selected so as to be capable of forming blue as visible light.

  Similarly to the emission wavelength, the wavelength bandwidth can be determined by the required range. As described above, even if the wavelength bandwidth is not ± 2 nm, for example, it may be a range that does not affect the human body. For example, it may be about ± 10 nm.

  The laser light emitting unit 40 (4) that emits the excitation light wavelength of the fluorescent angiographic agent may be in any wavelength band, similar to the laser light emitting units 40 (1) to 40 (3). That is, the wavelength of the laser light emitting unit 40 (4) may not be 780 ± 2 nm but may be, for example, 800 nm ± 5 nm near the peak of the excitation efficiency.

  Further, the wavelength of the laser emission section 40 (4) is not limited to that for indocyanine green, but may be the excitation light wavelength of other fluorescent angiography agents, for example, around 490 nm of fluorescein, around 400 nm of 5 ALA, etc. Absent.

  Furthermore, you may share the wavelength which comprises visible light, and the excitation light wavelength of a fluorescent angiography agent. For example, the blue color of the laser light emitting unit 40 (1) may be 490 nm that is around the excitation light of the fluorescein fluorescent angiographic agent. In this case, at the time of use as visible light illumination, the laser light emission control unit 10 causes the laser light emission unit 40 (1) to emit light together with the laser light emission unit 40 (2) and the laser light emission unit 40 (3). White light can be configured.

  On the other hand, at the time of fluorescent angiography observation, the laser emission control unit 10 can efficiently use the laser emission unit 40 according to the purpose by controlling only the laser emission unit 40 (1) to emit light.

  Further, the light emitting element used in the illumination device 100 according to the first embodiment is not limited to an LED or a semiconductor laser. It goes without saying that other laser elements or light emitting elements may be used as long as the wavelength and band can be controlled.

The lighting device according to the first embodiment described above has the following effects.
(Effect 1) According to the present invention, there is provided a first configuration capable of obtaining reflected light from a deep part on a subject, particularly a living body, by emitting light at a necessary power density at a necessary power density. . As a result, the entire subject becomes bright and clear. Further, by providing this first configuration, it is possible to obtain not only the object surface but also a deep observation light image.

  (Effect 2) According to the present invention, the second configuration is provided that enables light emission when a required wavelength is required. As a result, light components with unnecessary wavelengths can be suppressed, and adverse effects on the subject, the surgeon, and the observer can be suppressed. Further, by providing this second configuration, it is possible to further irradiate selectively the excitation light wavelength necessary for obtaining the fluorescence from the subject as well as improving the efficiency.

  (Effect 3) According to the present invention, there is provided a third configuration in which a semiconductor laser can be used as the light emitting means. As a result, it is possible to obtain a light source with higher output and easier wavelength limitation.

  (Effect 4) According to the present invention, there is provided a fourth configuration in which a solid state device such as a laser can be used as the light emitting means. As a result, the self-diagnosis function of the solid state device can be realized based on the detection result of the light emission state by utilizing the aging characteristics of the solid state device.

  DESCRIPTION OF SYMBOLS 10 Laser light emission control part, 30, 30 (1) -30 (4) Laser drive part, 31 Light emitting element drive circuit, 32a, 32b Detection circuit, 40, 40 (1) -40 (4) Laser light emission part, 41a, 41b Light emitting element, 42 Temperature sensor, 43 Cooling device, 60 Rod integrator for laser beam mixing (mixing part), 93a Directly penetrated light, 93b Reflected or diffused light of penetrated direct light, 94a Direct light, 94b Direct light Reflected light, 100 lighting equipment.

Claims (10)

An illumination device for irradiating a subject using a light emitting element of a semiconductor laser as a light source,
A plurality of light emitting sections for emitting a plurality of light having different wavelength bands;
A light emission control unit for controlling a light emission output of the light emitting element in each of the plurality of light emitting units;
A mixing unit that mixes light emission outputs from a plurality of light emitting units, and generates output light that irradiates the subject;
With
The light emission control unit controls a wavelength and a power density for each of the light emission outputs of the plurality of light emitting units, and obtains reflected light from a deep part of the subject. The plurality of light emitting units are:
A first light emitting unit that emits light in a first wavelength band;
A second light emitting unit that emits light in a second wavelength band not including the first wavelength band;
A third light emitting unit that emits a third wavelength band not including the first wavelength band and the second wavelength band;
A fourth light emitting unit that emits a fourth wavelength band not including the first wavelength band, the second wavelength band, and the third wavelength band;
Have
The light emission control unit controls the light emission output of each of the first light emitting unit, the second light emitting unit, the third light emitting unit, and the fourth light emitting unit,
2. The mixing unit mixes outputs of the first light emitting unit, the second light emitting unit, the third light emitting unit, and the fourth light emitting unit to generate the output light. The lighting device described in 1. The lighting device according to claim 1, wherein the light emission control unit controls the light emission output for a plurality of or a plurality of light emitting units. For each of the plurality of light emitting units, further comprising a detection circuit for measuring a forward current of the light emitting element,
The light emission control unit controls each of the light emitting units such that the forward current measured by the detection circuit falls within a predetermined current range for each light emitting unit. The illumination device according to any one of the above. The illumination according to claim 4, wherein the light emission control unit has a self-diagnosis function that determines that the corresponding light emission unit has deteriorated when the forward current measured by the detection circuit is lower than the current range. apparatus. Each of the plurality of light emitting units includes a first light emitting element and a second light emitting element,
When the light emission control unit determines that the first light emitting element has deteriorated due to the self-diagnosis function while controlling the first light emitting element, the light emitting control unit starts from the first light emitting element. The lighting device according to claim 5, wherein the control target is switched to the two light emitting elements to continue light emission. For each of the plurality of light emitting units, a temperature sensor that detects the temperature of the light emitting element;
A cooling device for cooling the light emitting element;
Further comprising
When the temperature of the light emitting element detected by the temperature sensor exceeds a predetermined temperature range for each light emitting unit, the light emission control unit causes the temperature of the light emitting element to be reduced by the cooling device. The lighting device according to any one of claims 1 to 6, wherein each light emitting unit is controlled so as to be within a range. The lighting device according to claim 1, wherein the plurality of light emitting units include a light emitting unit that emits light at an excitation wavelength of indocyanine green that is a fluorescent angiographic contrast agent. The lighting device according to any one of claims 1 to 7, wherein the plurality of light emitting units include a light emitting unit that emits light at an excitation wavelength of fluorescein that is a fluorescent angiographic contrast agent. The illuminating device according to claim 1, wherein the plurality of light emitting units include a light emitting unit that emits light at an excitation wavelength of 5 ALA that is a fluorescent angiographic contrast agent.

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