WO2023153146A1

WO2023153146A1 - Illumination device and illumination method

Info

Publication number: WO2023153146A1
Application number: PCT/JP2023/001038
Authority: WO
Inventors: 優太中村
Original assignee: ニデックプレシジョン株式会社
Priority date: 2022-02-08
Filing date: 2023-01-16
Publication date: 2023-08-17

Abstract

An illumination device 10 according to one embodiment of the present invention comprises: a light source 11 for emitting illumination light L; a branch unit 13 for dividing the illumination light L emitted from the light source 11 into first illumination light L1 and second illumination light L2; a diffraction unit 14 for diffracting some of the first illumination light L1, emitting the diffracted light to the exterior, and reflecting the remaining light; a first detection unit 15 for detecting the quantity of light reflected by the diffraction unit 14 within the first illumination light L1; a second detection unit 16 for detecting the quantity of second illumination light; and a control unit 17 for controlling the light source 11 on the basis of at least the quantity of light detected by the first detection unit 15, among the quantity of light detected by the first detection unit 15 and the quantity of light detected by the second detection unit 16.

Description

Lighting device and lighting method

The present invention relates to lighting devices and lighting methods.

Conventionally, moving bodies such as automobiles that are equipped with lighting devices and perform various displays by projecting light from the lighting devices have been known. The moving body of Patent Document 1 is equipped with an illumination device that irradiates a region to be illuminated with coherent light emitted from a light source via a diffractive optical element. The direction in which the moving body moves is projected onto the illuminated area according to the pattern formed on the diffractive optical element. That is, the illumination device functions as a direction display device. Although the coherent light emitted from the light source has a high intensity, it is attenuated to an intensity that does not adversely affect human eyes by passing through the diffractive optical element.

JP 2021-27014 A

If light whose intensity is not attenuated due to damage or the like is emitted and enters the human eye, there is a risk of damage to the human eye. requested. In Patent Literature 1, two terminals are electrically connected to each other when the diffractive optical element is attached to the housing, and the detachment of the diffractive optical element is detected when the connection between the terminals is broken. However, there is a problem that the apparatus of Patent Document 1 cannot detect damage other than detachment, such as opening a hole in a part of the diffractive optical element.

An illumination device according to one embodiment includes a light source that emits illumination light, a branching portion that splits the illumination light emitted from the light source into first illumination light and second illumination light, and one of the first illumination light. a diffraction portion that diffracts a portion of the light and reflects the other portion; a first detection portion that detects the amount of light reflected by the diffraction portion in the first illumination light; a second detection unit that detects the amount of illumination light; and based on at least the amount of light detected by the first detection unit out of the amount of light detected by the first detection unit and the amount of light detected by the second detection unit. and a controller for controlling the light source.

An illumination method according to one embodiment includes emitting illumination light from a light source, detecting the amount of reflected light reflected by a diffraction section in the first illumination light branched from the illumination light by a branching section, The light amount of the second illumination light branched from the illumination light is detected, and the light source is controlled based on at least the light amount of the reflected light among the light amount of the reflected light and the light amount of the second illumination light.

According to the present invention, it is possible to determine whether or not the diffraction section is damaged based on the illumination light, and control the emission of the illumination light from the light source.

FIG. 1 is a block diagram showing the main configuration of the lighting device. FIG. 2 is a flow chart explaining the operation of the lighting device. FIG. 3 is a flow chart explaining the operation of the lighting device.

A detailed description of the lighting device according to the embodiment will be given below with reference to the drawings.

<About the lighting device>
A lighting device is provided in a moving body, which is a movable device such as, for example, a railroad vehicle, automobile, truck, ship, airplane, helicopter, drone, and robot. The illumination device emits illumination light in the traveling direction of the moving body, and projects information regarding the traveling of the moving body, for example, onto a road surface. The lighting device projects, as information on progress, for example, arrows indicating the direction of travel, and characters such as "go straight", "turn right", "decelerate", and "accelerate". The illumination device is not limited to projecting the arrows and characters described above, and may project patterns, symbols, marks, illustrations, characters, pictograms, and the like. There is no limit to the number of lighting devices mounted on the moving object, and the number may be one or a plurality of two or more.

FIG. 1 is a block diagram showing the main configuration of the lighting device 10. FIG. The illumination device 10 has a light source 11 , an optical system 12 , a branching section 13 , a diffraction section 14 , a first detection section 15 , a second detection section 16 and a control section 17 . For convenience of explanation, an orthogonal coordinate system consisting of an x-axis and a y-axis is used as shown in FIG. The x-axis is set in the left-right direction of the paper surface of FIG. 1, and the y-axis is set in the vertical direction of the paper surface of FIG. 1, orthogonally crossing the x-axis.

The light source 11 is, for example, a laser diode (semiconductor laser), and receives power supply to emit illumination light L, which is laser light (coherent light), in the + direction of the x-axis. The light source 11 changes the amount of illumination light L under the control of the control unit 17 . That is, as will be described later in detail, the amount (intensity) of the illumination light L emitted by the light source 11 is controlled by changing the power (current) supplied under the control of the control unit 17 .

The optical system 12 is a collimator lens that is arranged on the + side of the x-axis with respect to the light source 11 and that shapes the illumination light L emitted from the light source 11 into parallel light. Although one lens is shown as the optical system 12 in FIG. 1, the optical system 12 may be composed of two or more lenses.

The branching unit 13 is an optical member such as a beam splitter or a half mirror, and branches the traveling direction of the incident illumination light L into the x-axis + side and the y-axis + side. That is, the branching portion 13 transmits part of the illumination light L traveling from the optical system 12 and reflects the other part (remaining portion) toward the + side of the y-axis. Light transmitted through the branching portion 13 of the illumination light L is referred to as first illumination light L1, and light reflected by the branching portion 13 is referred to as second illumination light L2. In the following description, it is assumed that the branching portion 13 transmits 50% of the illumination light L and reflects the remaining 50%.

The diffraction section 14 is arranged on the x-axis + side with respect to the branching section 13 and is illuminated by the first illumination light L1 that has passed through the branching section 13 . The diffraction section 14 is, for example, a diffraction grating such as a hologram element. As the hologram element, various known holograms such as Fourier transform type, Fresnel type, computer synthesis type, analog recording type, and relief type can be used. Information about the movement of the moving body is recorded in this hologram element. Part of the first illumination light L1 that has passed through the branching portion 13 passes through the diffraction portion 14 and is emitted to the outside of the lighting device 10 . As a result, the information recorded in the diffraction section 14 is projected outside the illumination device 10 (that is, forward in the traveling direction of the moving object).

The remaining portion of the first illumination light L1 that has passed through the branching portion 13 is reflected by the diffraction portion 14 . This reflected light (reflected light) travels to the x-axis − side and enters the branch portion 13 . This reflected light is reflected by the branching portion 13 toward the y-axis − side and enters the first detecting portion 15 .

The first detection unit 15 and the second detection unit 16 are photoelectric conversion elements such as photodiodes, for example. The first detection portion 15 is arranged on the y-axis minus side with respect to the branch portion 13 , and the second detection portion 16 is arranged on the y-axis + side with respect to the branch portion 13 . Light reflected by the branching portion 13 (that is, reflected light reflected by the diffraction portion 14 ) after being reflected by the diffraction portion 14 in the first illumination light L1 enters the first detection portion 15 . The first detection unit 15 converts this reflected light into an electric signal and outputs it to the control unit 17 as a first detection signal. This electrical signal (that is, the first detection signal) has a value (signal intensity) corresponding to the amount of reflected light incident on the first detection section 15 . Therefore, the first detector 15 detects the light intensity of the first illumination light L1. The second illumination light L2 is incident on the second detector 16 . The second detection unit 16 converts the incident second illumination light L2 into an electric signal and outputs the electric signal to the control unit 17 as a second detection signal. This electrical signal (that is, the second detection signal) has a value (signal intensity) corresponding to the amount of light incident on the second detection section 16 . Therefore, the second detector 16 detects the amount of light of the second illumination light L2.

The control unit 17 is composed of a CPU, a memory, and the like. The control unit 17 is a processor that controls each unit of the lighting device 10 by reading and executing a control program pre-recorded in a storage medium such as a flash memory. The control unit 17 controls the illumination light L emitted from the light source 11 by executing an illumination method whose details will be described later.

<About lighting method>
The amount of light detected by the first detection unit 15 (reflected light reflected by the diffraction unit 14) and the amount of the second illumination light L2 detected by the second detection unit 16 are determined by the illumination method executed by the control unit 17. The illumination light L emitted by the light source 11 is controlled based on the amount of light. Specifically, the control unit 17 performs light source control processing for stopping the emission of the illumination light L from the light source 11 based on the light amount of the first illumination light L1 detected by the first detection unit 15 . The control unit 17 performs light amount control processing for controlling the light amount of the illumination light L emitted by the light source 11 based on the light amount of the second illumination light L2 detected by the second detection unit 16 .

<About light source control processing>
The control unit 17 detects the light amount of the first illumination light L1 reaching the diffraction unit 14 based on the first detection signal output by the first detection unit 15 . As described above, the diffraction section 14 reflects part of the first illumination light L1 that has reached it, and this reflected light enters the first detection section 15 . Since the reflectance of the diffraction section 14 is a known value determined by the material of the diffraction section 14, etc., the light amount of the reflected light reflected by the diffraction section 14 and the light amount of the first illumination light L1 reaching the diffraction section 14 are has a proportional relationship. Therefore, the control unit 17 can handle (detect) the light amount of the reflected light detected by the first detection unit 15 as the light amount of the first illumination light L1.

The control unit 17 compares the detected light intensity of the first illumination light L1 with the preset first threshold Th1 and second threshold Th2. Note that the first threshold Th1 is, for example, a value obtained by multiplying the lower limit of the light amount of the first illumination light L1 by the reflectance of the diffraction section 14 . The lower limit of the amount of light of the first illumination light L1 is the amount of light necessary for making the projection pattern formed outside by the light emitted from the illumination device 10 visible when the diffraction section 14 is not damaged. value. The value of the first threshold Th1 is determined based on the results of simulation or the like, and the threshold voltage (current) corresponding to this first threshold Th1 is set in advance in the controller 17 . The control unit 17 has, for example, a comparator, and the comparator compares the threshold voltage (current) with the voltage (current) of the first detection signal output by the first detection unit 15, which is the light amount of the first illumination light L1. and outputs a signal according to the comparison result. Based on this signal, the control unit 17 performs processing according to the comparison result.

When the light amount of the first illumination light L1 is equal to or less than the first threshold value Th1, it is conceivable that damage (abnormality) such as opening of a hole occurs in the diffraction section 14 and the reflectance of the diffraction section 14 is reduced. That is, it is conceivable that the light amount of the first illumination light L1 that is transmitted without being reflected by the diffraction section 14 is increasing. In this case, since the amount of light emitted to the outside of the lighting device 10 is too large, there is a possibility that this light may have an adverse effect if it enters the eyes of an outsider. Therefore, when the calculated light amount of the first illumination light L1 is equal to or less than the first threshold value Th1, the control unit 17 stops the current supply from the power supply unit 20 to the light source 11, and the illumination light L from the light source 11 is Stop the emission.

Also, the second threshold Th2 is, for example, a value obtained by multiplying the upper limit of the light amount of the first illumination light L1 by the reflectance of the diffraction section 14 . The upper limit value of the light amount of the first illumination light L1 is a light amount value that does not adversely affect the light emitted from the lighting device 10 even if it enters the eyes of an outsider. The value of the second threshold Th2 is determined based on the result of simulation or the like, and the threshold voltage (current) corresponding to this second threshold Th2 is set in advance in the controller 17 . The comparator of the control unit 17 compares this threshold voltage (current) with the voltage (current) of the first detection signal output by the first detection unit 15, which is the light intensity of the first illumination light L1, and outputs the voltage (current) according to the comparison result. output a signal. Based on this signal, the control unit 17 performs processing according to the comparison result. If the amount of light of the first illumination light L1 calculated by the control unit 17 is equal to or greater than the second threshold value Th2, there is no abnormality in the diffraction unit 14, but if the second detection unit 16 fails, for example, the diffraction unit 14 is It is conceivable that the amount of transmitted first illumination light L1 is increasing. That is, since the amount of light emitted to the outside of the lighting device 10 is too large, there is a risk that this light will have an adverse effect if it enters the eyes of an outsider. Therefore, when the calculated light amount of the first illumination light L1 is equal to or greater than the second threshold value Th2, the control unit 17 stops the current supply from the power supply unit 20 to the light source 11, and the illumination light L from the light source 11 is Stop the emission.

Instead of the control unit 17 treating the amount of reflected light detected by the first detection unit 15 as the amount of light of the first illumination light L1, the reflectance of the diffraction unit 14 and the amount of light detected by the first detection unit 15 The light amount of the first illumination light L1 reaching the diffraction section 14 may be detected (calculated) based on the light amount of the reflected light. In this case, the first threshold Th1 is the above-described lower limit of the light amount of the first illumination light L1, and the second threshold Th2 is the above-described upper limit of the light amount of the first illumination light L1.

The light source control process described above is executed by the control unit 17 at predetermined time intervals.

The processing performed by the control unit 17 will be described with reference to the flowchart of the light amount control processing shown in FIG. Each process shown in the flowchart is performed by the control unit 17 reading a program stored in a storage medium and executing the program.

In step S10, the control unit 17 supplies specified power (current) from the power supply unit 20 to the light source 11 to cause the light source 11 to emit the illumination light L. After that, the process proceeds to step S11. In step S11 , the control unit 17 uses the first detection signal output from the first detection unit 15 to detect the value of the light amount of the first illumination light L1 . After that, the process proceeds to step S12.

In step S12, the control unit 17 compares the detected light intensity value of the first illumination light L1 with the first threshold value Th1 and the second threshold value Th2. When the value of the light quantity of the first illumination light L1 is greater than the first threshold Th1 and smaller than the second threshold Th2, the controller 17 makes an affirmative determination, and the process returns to step S11. If the value of the amount of light of the first illumination light L1 is equal to or less than the first threshold Th1 or equal to or greater than the second threshold Th2, the controller 17 makes a negative determination, and the process proceeds to step S13. In step S13, the control unit 17 stops the power supply to the light source 11, stops the emission of the illumination light L from the light source 11, and ends the process.

<Regarding light intensity control processing>
First, the control unit 17 supplies specified power (current) from the power supply unit 20 to the light source 11 to cause the light source 11 to emit illumination light L. As shown in FIG. Then, the control unit 17 detects the light amount of the second illumination light L2, that is, the light amount of the illumination light L emitted from the light source 11, based on the second detection signal output by the second detection unit 16. FIG. As described above, the second illumination light L2 is the light of the illumination light L that is reflected by the branching portion 13 toward the + side of the y-axis. As described above, the reflectance of the branching portion 13 is 50%, which is a known value. A proportional relationship exists. Therefore, the control unit 17 can handle (detect) the light amount of the second illumination light L2 detected by the second detection unit 16 as the light amount of the illumination light L.

The control unit 17 compares the detected light intensity of the illumination light L with the preset third threshold Th3 and fourth threshold Th4. Note that the third threshold Th3 is a value obtained by multiplying the lower limit value of the light amount of the illumination light L by 50%, which is the reflectance of the branch portion 13 . The lower limit value of the light intensity of the illumination light L is the value of the light intensity necessary for the light emitted from the illumination device 10 to form an external projection pattern to be visible. The value of the third threshold Th3 is determined based on the results of simulation or the like, and a threshold voltage (current) corresponding to the third threshold Th3 is set in the controller 17 in advance. The comparator of the control unit 17 compares this threshold voltage (current) with the voltage (current) of the second detection signal output by the second detection unit 16, which is the amount of light of the second illumination light L2. output a signal. Based on this signal, the control unit 17 performs processing according to the comparison result. Further, the fourth threshold Th4 is a value obtained by multiplying the upper limit value of the light amount of the illumination light L by 50%, which is the reflectance of the branch portion 13 . The upper limit value of the light amount of the illumination light L is a light amount value that does not adversely affect the light emitted from the lighting device 10 even if it enters the eyes of an outsider. The value of the fourth threshold Th4 is determined based on the results of simulation or the like, and a threshold voltage (current) corresponding to the fourth threshold Th4 is set in the controller 17 in advance. The comparator of the control unit 17 compares this threshold voltage (current) with the voltage (current) of the second detection signal output by the second detection unit 16, which is the amount of light of the second illumination light L2. output a signal. Based on this signal, the control unit 17 performs processing according to the comparison result.

The control unit 17 compares the calculated value of the light amount of the illumination light L with the third threshold Th3, and if the value of the light amount of the illumination light L is smaller than the third threshold Th3, the illumination emitted from the light source 11 The amount of light L is increased. Specifically, the control unit 17 increases the power (current) supplied from the power supply unit 20 to the light source 11 . In this case, the controller 17 increases the power supply amount by a predetermined value. Alternatively, the control unit 17 increases the power supply amount based on the difference between the calculated value of the light intensity of the illumination light L and the third threshold value Th3. As a result, the amount of illumination light L emitted from the light source 11 increases, and the projection pattern formed outside by the light emitted from the lighting device 10 becomes visible.

The control unit 17 compares the calculated value of the light amount of the illumination light L with a fourth threshold Th4, and if the value of the light amount of the illumination light L is larger than the fourth threshold Th4, the illumination emitted from the light source 11 The amount of light L is reduced. Specifically, the control unit 17 reduces the power (current) supplied from the power supply unit 20 to the light source 11 . In this case, the controller 17 reduces the power supply amount by a predetermined value. Alternatively, the control unit 17 reduces the power supply amount based on the difference between the calculated value of the light amount of the illumination light L and the fourth threshold value Th4. Accordingly, even if the light emitted from the lighting device 10 enters the eyes of an outsider, it is possible to suppress adverse effects.

Instead of the control unit 17 treating the light amount of the second illumination light L2 detected by the second detection unit 16 as the light amount of the illumination light L, the light amount of the second illumination light L2 is doubled so that the light source The amount of illumination light L emitted from 11 may be detected (calculated). In this case, the third threshold Th3 is the lower limit of the amount of illumination light L described above, and the fourth threshold Th4 is the upper limit of the amount of illumination light L described above.

It should be noted that the light amount control process described above is executed by the control unit 17 at predetermined time intervals.

In step S20, the control unit 17 detects the value of the light amount of the illumination light L using the second detection signal output from the second detection unit 16. After that, the process proceeds to step S21. In step S21, the controller 17 determines whether or not the calculated value of the light intensity of the illumination light L is smaller than the third threshold Th3. When the value of the light amount of the illumination light L is smaller than the third threshold Th3, the controller 17 makes an affirmative determination, and the process proceeds to step S22. In step S22 , the control unit 17 increases the power supplied from the power supply unit 20 to the light source 11 to increase the amount of illumination light L emitted by the light source 11 . After that, the process returns to step S20.

In step S21, when the value of the light quantity of the illumination light L is equal to or greater than the third threshold Th3, the control unit 17 makes a negative determination, and the process proceeds to step S23. In step S23, the controller 17 determines whether or not the calculated value of the light intensity of the illumination light L is greater than the fourth threshold Th4. When the value of the light quantity of the illumination light L is larger than the fourth threshold value Th4, the controller 17 makes an affirmative determination, and the process proceeds to step S24. In step S24 , the control unit 17 reduces the power supplied from the power supply unit 20 to the light source 11 to reduce the amount of illumination light L emitted by the light source 11 . After that, the process returns to step S20. Further, in step S23, when the calculated value of the light amount of the illumination light L is equal to or smaller than the fourth threshold value Th4, the controller 17 makes a negative determination, and the process returns to step S20.

By performing the above-described light amount control process, the illumination light L emitted from the light source 11 is prevented from becoming insufficient or excessive.

According to the embodiment described above, the following effects are obtained.

(1) The illumination device 10 includes a light source 11 , a branching section 13 , a diffraction section 14 , a first detection section 15 , a second detection section 16 and a control section 17 . The light source 11 emits the illumination light L, and the splitter 13 splits the illumination light L into the first illumination light L1 and the second illumination light L2. The diffraction section 14 diffracts a part of the first illumination light L1 and emits it to the outside, and reflects the rest. The first detection unit 15 detects the amount of light reflected by the diffraction unit 14 in the first illumination light L1. The second detector 16 detects the amount of light of the second illumination light L2. The control unit 17 controls the illumination light L emitted by the light source 11 based on the amount of light detected by the first detection unit 15 and the amount of light detected by the second detection unit 16 . As a result, damage such as a hole in a part of the diffraction section 14 can be detected by the first detection signal output by the first detection section 15 . In addition, since the illumination light L emitted from the light source 11 is controlled based on the first detection signal, damage to the diffraction section 14 (for example, a hole in a part of the diffraction section 14, etc.) may cause Emission of illumination light L having an intensity (amount of light) that adversely affects human eyes is suppressed. As a result, the amount of illumination light L emitted from the light source 11 is stabilized, and the safety of the illumination device 10 can be ensured.

(2) The control unit 17 causes the light source 11 to stop emitting the illumination light L based on the amount of light detected by the first detection unit 15 . As a result, the high-intensity illumination light L is emitted, and the danger of entering the human eye and having an adverse effect can be suppressed, and the safety of the illumination device 10 can be ensured.

(3) The control unit 17 stops emission of the illumination light L when the amount of light detected by the first detection unit 15 is equal to or less than the first threshold value Th1. When the light amount of the first illumination light L1 reflected by the diffraction section 14 is small, it is conceivable that the light amount of the first illumination light L1 emitted to the outside from the damaged portion of the diffraction section 14 is large. Therefore, when the amount of light detected by the first detection unit 15 is equal to or less than the first threshold value Th1, there is a high possibility that the diffraction unit 14 is damaged. Safety can be ensured.

(4) The control unit 17 stops emission of the illumination light L when the amount of light detected by the first detection unit 15 is greater than or equal to a second threshold Th2 that is greater than the first threshold Th1. As a result, when the amount of illumination light L emitted from the light source 11 is excessively large, the emission of the high-intensity illumination light L, which may enter the human eye and adversely affect the human eye, is stopped. 10 safety can be ensured.

(5) The control unit 17 increases the light amount of the illumination light L emitted by the light source 11 when the light amount detected by the second detection unit 16 is smaller than the third threshold Th3. Accordingly, the light amount of the illumination light L actually emitted from the light source 11 is detected based on the light amount of the second illumination light L2, and the light amount of the illumination light L is adjusted to provide a stable light amount. can be emitted from

(6) The control unit 17 reduces the light amount of the illumination light L emitted from the light source 11 when the amount of light detected by the second detection unit 16 is larger than the fourth threshold Th4, which is larger than the third threshold Th3. . Accordingly, the light amount of the illumination light L actually emitted from the light source 11 is detected based on the light amount of the second illumination light L2, and the light amount of the illumination light L is adjusted to provide a stable light amount. can be emitted from

The above-described embodiment can be modified as follows.

<First modification>
The light source control process is not limited to stopping emission of the illumination light L from the light source 11 when the amount of light detected by the first detection unit 15 is equal to or less than the first threshold Th1 or equal to or greater than the second threshold Th2. For example, the controller 17 may reduce the amount of illumination light L emitted from the light source 11 . In this case, the controller 17 can reduce the amount of illumination light L by reducing the power supplied to the light source 11 . The amount of illumination light L at this time may be reduced according to the difference between the amount of light detected by the first detection unit 15 and the first threshold value Th1 or the second threshold value Th2, or may be determined in advance. may be reduced by a predetermined percentage.

<Second modification>
As shown in the block diagram of FIG. 1, the branching unit 13 is arranged after the optical system 12 (on the + side of the x-axis), and the branching unit 13 branches the illumination light L that has been shaped into parallel light by the optical system 12. not limited to When the branching section 13 is configured by a beam splitter, the optical system 12 is arranged after the branching section 13 (on the + side of the x-axis), and the optical system 12 receives the first illumination light L1 branched by the branching section 13. It may be shaped into parallel light.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. For example, the control unit 17 may perform only the light source control process. In this case, the control unit 17 controls the light source 11 using only the first detection signal output from the first detection unit 15 (that is, the amount of light reflected by the diffraction unit 14 in the first illumination light L1). Illumination light L emitted from may be controlled. In other words, of the first detection signal output from the first detection unit 15 and the second detection signal output from the second detection unit 16, the control unit 17 uses at least the first detection signal to detect the light source 11. The emitted illumination light L may be controlled.

DESCRIPTION OF SYMBOLS 10... Illuminating device, 11... Light source, 12... Optical system, 13... Branch part, 14... Diffraction part, 15... First detection part, 16... Second detection part, 17... Control part, 20... Power supply part

Claims

a light source that emits illumination light;
a branching unit that branches the illumination light emitted from the light source into first illumination light and second illumination light;
a diffraction unit that diffracts a part of the first illumination light and emits it to the outside and reflects the other part;
a first detection unit that detects the amount of light reflected by the diffraction unit in the first illumination light;
a second detection unit that detects the amount of light of the second illumination light;
a control unit that controls the light source based on at least the amount of light detected by the first detection unit out of the amount of light detected by the first detection unit and the amount of light detected by the second detection unit. lighting device.
The lighting device according to claim 1,
The lighting device, wherein the controller causes the light source to stop emitting the illumination light based on the amount of light detected by the first detector.
The lighting device according to claim 2,
The lighting device, wherein the controller causes the light source to stop emitting the illumination light when the amount of light detected by the first detector is equal to or less than a first threshold.
The lighting device according to claim 3,
The lighting device, wherein the controller causes the light source to stop emitting the illumination light when the amount of light detected by the first detector is equal to or greater than a second threshold larger than the first threshold.
In the lighting device according to any one of claims 1 to 4,
The lighting device, wherein the control unit increases the amount of the illumination light emitted by the light source when the amount of light detected by the second detection unit is smaller than a third threshold.
In the lighting device according to claim 5,
The lighting device, wherein the control unit reduces the amount of the illumination light emitted from the light source when the amount of light detected by the second detection unit is larger than a fourth threshold that is larger than the third threshold.
emitting illumination light from the light source,
Detecting the amount of reflected light reflected by the diffraction section, out of the first illumination light branched from the illumination light by the branching section,
detecting the amount of second illumination light branched from the illumination light by the branching unit;
The illumination method, wherein the light source is controlled based on at least the amount of the reflected light out of the amount of the reflected light and the amount of the second illumination light.