WO2018011986A1

WO2018011986A1 - Scanning endoscope

Info

Publication number: WO2018011986A1
Application number: PCT/JP2016/071024
Authority: WO
Inventors: 祐平高田
Original assignee: オリンパス株式会社
Priority date: 2016-07-15
Filing date: 2016-07-15
Publication date: 2018-01-18

Abstract

For the purpose of acquiring an image having good image quality even when deterioration of a laser light source causes a reduction in the amount of light, a scanning endoscope (1) according to the present invention is equipped with: a laser light source unit (10); a current control unit (12) that controls a drive current for the laser light source unit (10); an optical fiber (5) that guides the laser light output from the laser light source unit (10); a scanner (6) that vibrates an emission end (5a) of the optical fiber (5) and two-dimensionally scans the laser light emitted from the emission end (5a); a light amount detection unit (11) that detects the amount of laser light output from the laser light source unit (10); and a characteristic generation unit (17) that generates light-amount-and-current characteristics in which are associated the amount of laser light detected by the light amount detection unit (11) and the drive current input into the laser light source unit (10) by the current control unit (12), said current control unit (12) controlling the driving current on the basis of the light-amount-and-current characteristics generated by the characteristic generation unit (17) so that the target light amount is emitted.

Description

Scanning endoscope

The present invention relates to a scanning endoscope.

Vibrating the exit end of the optical fiber that guides the laser light from the laser light source, scanning the laser light emitted from the exit end two-dimensionally on the subject, and receiving the light returning from each scanning position of the subject There is known a scanning endoscope that acquires an image by the method (for example, see Patent Document 1).
This scanning endoscope adjusts the brightness of an observation image without performing image processing by adjusting the amount of illumination light according to the scanning position for an arbitrary area in the observation image.

JP 2010-115391 A

In order to obtain an observation image with good image quality by a scanning endoscope, it is desirable to output a sufficient amount of light, but if the laser light source is used for a long time, the laser light source deteriorates and the light amount decreases. As a result, the image quality is degraded.
The present invention has been made in view of the above-described circumstances, and provides a scanning endoscope capable of acquiring an image with good image quality even when the amount of light is reduced due to deterioration of a laser light source. It is aimed.

One embodiment of the present invention includes a laser light source unit, a current control unit that controls a drive current of the laser light source unit, an optical fiber that guides laser light emitted from the laser light source unit, and an emission of the optical fiber. A scanner that vibrates an end and scans the laser light emitted from the emission end in a two-dimensional manner, a light amount detection unit that detects a light amount of the laser light emitted from the laser light source unit, and the light amount detection unit A characteristic generation unit that generates a current light amount characteristic that associates the light amount detected by the current control unit with the drive current input to the laser light source unit, and the current control unit includes the characteristic In the scanning endoscope, the driving current is controlled so as to be a target light amount based on the current light amount characteristic generated by the generation unit.

According to this aspect, when the drive current controlled by the current control unit is applied to the laser light source unit, the laser light source having a light amount determined based on the current light amount characteristic is emitted from the laser light source unit and guided by the optical fiber. It is emitted and ejected from the exit end. By oscillating the exit end by the operation of the scanner, the laser light emitted from the exit end is scanned two-dimensionally on the subject, so that return light from each scanning position of the subject is detected and associated with the scanning position. Thus, an image of the subject can be acquired.

In this case, the light amount of the laser light emitted from the laser light source unit is detected by the light amount detection unit, and a current light amount characteristic in which the detected light amount is associated with the drive current is generated and generated by the characteristic generation unit. Based on the current light quantity characteristics, the drive current is controlled by the current control unit so as to achieve the target light quantity.

If the laser light source part deteriorates over time, the light quantity decreases even if a constant drive current is input to the laser light source part, so the current light quantity characteristic fluctuates, and if the same current light quantity characteristic is used, the target light quantity It becomes impossible to obtain a drive current for achieving the above. According to this aspect, since the drive current for achieving the target light amount is calculated based on the current light amount characteristic generated by detecting the light amount of the laser light from the laser light source unit, the target light amount can be achieved with high accuracy. Thus, it is possible to acquire an image with good image quality.

In the above aspect, the laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges, and the characteristic generation unit generates the current light amount characteristic for each of the laser light sources, The target light amount of the laser light source may be a fixed value having a predetermined light amount ratio.
By doing so, laser beams having different wavelength ranges are emitted from a plurality of laser light sources with a target light amount having a predetermined light amount ratio, and illumination light of a predetermined color is emitted from the laser light source unit. In this state, even if any of the laser light sources deteriorates, the drive current is controlled based on the current light amount characteristics generated for each laser light source. Therefore, a target light amount that is a fixed value is set for each laser light source. The image can be recovered with high accuracy and an image with good image quality can be acquired.

Further, in the above aspect, the laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges, and the characteristic generation unit generates the current light amount characteristic for each of the laser light sources. Update the target light quantity of each laser light source with a predetermined light quantity ratio and the laser light source with the greatest decrease in the light quantity detected by the light quantity detection unit, before the update A target light amount setting unit that sets the light amount that can be achieved by the current light amount characteristic after the update by the drive current that achieves the target light amount before the update by the current light amount characteristic may be provided.

In this way, when the laser light source unit deteriorates with time, the light amount detected by the light amount detection unit decreases. For laser light sources with the greatest decrease in light amount, the amount of light that can be achieved when a drive current that achieves the target light amount before update is input is set as a new target light amount. Since the target light amount is set by the target light amount setting unit so as to be the light amount ratio, the light amount ratio is kept constant so as not to fluctuate. By reducing the target light amount when the laser light source is deteriorated, an excessive increase in the current input to the deteriorated laser light source can be prevented, and the laser light source can be prevented from being acceleratedly deteriorated.

Further, in the above aspect, the laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges, and the characteristic generation unit generates the current light amount characteristic for each of the laser light sources. When the drive current that is updated and has the predetermined light quantity ratio as the target light quantity of each laser light source and achieves the target light quantity before update by the updated current light quantity characteristic is equal to or less than a predetermined threshold value Is a fixed value, and when the value exceeds the threshold, the laser light source detected by the light amount detection unit has the greatest decrease in light amount before the update due to the current light amount characteristic before the update. A target light amount setting unit that sets the light amount that can be achieved by the updated current light amount characteristic by the drive current that achieves the target light amount may be provided.

By doing so, the target light quantity setting unit fixes the constant light quantity until the drive current exceeding the predetermined threshold is required to obtain the target light quantity as the deterioration of the laser light source progresses. When the laser beam is emitted and the predetermined threshold value is exceeded, the target light amount setting unit reduces the target light amount to prevent an excessive increase in the current input to the deteriorated laser light source. Can be prevented from being accelerated.

Further, in the above aspect, the laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges, and the characteristic generation unit generates the current light amount characteristic for each of the laser light sources. A target light amount setting unit that is updated and has a predetermined light amount ratio as a target light amount of each laser light source and is set by a predetermined function that decreases with time may be provided.

In this way, the drive current is controlled so that the target light amount decreases with time according to a predetermined function, so that an excessive increase in the current input to the deteriorated laser light source is prevented, and the laser light source Can be prevented from being accelerated.

Further, in the above aspect, the target light amount setting unit is configured to use the drive current that achieves the target light amount before the update by the current light amount characteristic before the update. A large target light amount may be set.
In this way, the target light quantity is lower than the target light quantity before the update, but cannot be achieved without increasing the drive current, so that the target light quantity can be lowered gradually without affecting the image quality. The lifetime of the light source can be extended.
In the above aspect, the characteristic generation unit may generate the current light quantity characteristic at a predetermined timing.

According to the present invention, it is possible to obtain an image with good image quality even when the light amount is reduced due to deterioration of the laser light source.

1 is an overall configuration diagram showing a scanning endoscope according to an embodiment of the present invention. It is a figure which shows the time change of the light quantity of the laser beam inject | emitted from the laser light source of the scanning endoscope of FIG. It is a figure explaining the calculation method of the drive current of the laser light source in the scanning endoscope of FIG. 4 is a flowchart illustrating a method for adjusting a drive current of the laser light source of FIG. 3. It is a figure which shows the modification of the calculation method of the drive current of FIG. 6 is a flowchart illustrating a method for adjusting a drive current of the laser light source of FIG. 5. It is a figure which shows an example of the measurement timing of the electric current light quantity characteristic in the scanning endoscope of FIG. It is a figure which shows the other example of the measurement timing of the current light quantity characteristic in the scanning endoscope of FIG. It is a figure which shows the time change of the light quantity of the laser beam inject | emitted from the laser light source in the modification of the scanning endoscope of FIG. 10 is a flowchart illustrating a method for adjusting the drive current of the laser light source of FIG. 9. 10 is a flowchart for explaining a method for adjusting a drive current of a laser light source in another modification of the scanning endoscope of FIG. It is a figure which shows the time change of the light quantity of the laser beam inject | emitted from the laser light source in the other modification of the scanning endoscope of FIG.

Hereinafter, a scanning endoscope 1 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the scanning endoscope 1 according to the present embodiment includes an endoscope body 2, a control device 3, and a display 4.

The endoscope body 2 includes a single mode fiber (optical fiber) 5 that guides laser light, and a scanner 6 that vibrates the exit end 5a of the single mode fiber 5 in a direction perpendicular to the longitudinal axis of the single mode fiber 5. And a light receiving fiber 7 for receiving the return light from the subject A.
The scanner 6 includes piezoelectric elements (not shown) arranged at equal intervals in the circumferential direction on the side surface of the single mode fiber 5 at a position spaced apart from the exit end 5 a of the single mode fiber 5.

The control device 3 causes a plurality of

laser light sources

8 a, 8 b, and 8 c that respectively emit laser beams in the respective RGB wavelength regions and the laser light emitted from the

laser light sources

8 a, 8 b, and 8 c to enter the single mode fiber 5. A light source unit (laser light source unit) 10 having a coupler 9 is provided. A light amount detector 11 is connected to the coupler 9. The light quantity detection unit 11 branches and detects a part of the light quantity of the laser light emitted from each

laser light source

8a, 8b, 8c, for example, 1% to 5%.

Further, the control device 3 includes a current control unit 12 that controls each of the

laser light sources

8a, 8b, and 8c, an actuator driver 13 that controls the scanner 6, and a photodetector that detects return light received by the light receiving fiber 7. 14, the AD converter (ADC) 15 that AD converts the return light detected by the photodetector 14, the intensity of the return light converted into a digital signal by the AD converter 15, and the scanning position In addition, a signal processing unit 16 that generates an image of the return light and a control unit (characteristic generation unit, target light amount setting unit) 17 that controls them are provided.

A storage unit 18 is connected to the control unit 17. The control unit 17 generates a current light amount characteristic based on the light amount detected by the light amount detection unit 11 and stores the generated current light amount characteristic in the storage unit 18 to update it.
The control unit 17 reads the latest current light amount characteristic stored in the storage unit 18 and calculates a drive current for achieving the target light amount. In the present embodiment, the target light amount is a fixed value.

The current controller 12 drives the

laser light sources

8a, 8b, and 8c in the order of RGB. The light amount detection unit 11 constantly monitors the light amount in order to monitor a sudden light amount abnormality during use of the endoscope, and the detected light amount data is stored in the storage unit 18.

Since the laser light emitted from the emission end 5a of the single mode fiber 5 is non-diffused light, light energy that is limited to such an extent that it can be avoided by blinking or the like even when directly incident on the eyes is emitted. Designed to. For example, the amount of emitted laser light is set to an average of 5 mW or less for the entire RGB so that a sufficient amount of light can be irradiated within the range of laser safety.

Here, a method for generating the current light quantity characteristic will be described below.
In order to generate the current light amount characteristic, for example, the current light amount characteristic is generated by using a process of gradually decreasing the laser light amount after the use of the endoscope and before the emission of the laser light is completely stopped. That is, as shown in FIG. 2, a data set in which the drive currents input from the current control unit 12 to the

laser light sources

8 a, 8 b, and 8 c in the above process are associated with the light amounts detected by the light amount detection unit 11. By storing a plurality of sets, it is possible to generate a current light quantity characteristic. The generated current light quantity characteristic is stored in the storage unit 18.

Next, a method for adjusting the drive current using the generated current light quantity characteristic will be described below.
Multiple sets of current and light quantity data sets are stored in the process until the laser beam emission is completely stopped. After the laser beam emission is completely stopped, the power is turned on again and the laser beam is emitted. When this is done, as shown in FIG. 4, the data set stored in the storage unit 18 is read (step S1), and the current light quantity characteristic is calculated.

Here, when oscillates laser light exceeds the threshold current I _th as shown in FIG. 3, by utilizing the fact that light intensity is proportional to the current increment, as a current light amount characteristics are shown in the following formula (1) A linear function is used.
L = a × (I−I _th ) (1)
Here, L is the amount of light, a is the slope, and I is the drive current.

In this function, the inclination a and the threshold current I _th is the unknown can be determined by the least square method using the read out from the storage unit 18, a data set of the drive current I and light intensity L at a plurality of points (Step S2).
Then, by using the inclination a and the threshold current I _th determined by the equation (1), so that the laser beam of the target light quantity L ₀ is emitted, the current value I _{0 'is} calculated (step S3).

That is, according to the current light quantity characteristic indicated by the two-dot chain line in FIG. 3, the scanning endoscope 1 is used by controlling the drive current to a value I ₀ that can emit the laser light having the target light quantity L ₀ . a

laser light source

8a, 8b, the deterioration over time of 8c, was reduced to the amount of light L ₁ at the time of endoscope use ends. In this case, since the current light quantity characteristic changes as indicated by a solid line in FIG. 3, the current light quantity characteristic represented by the formula (1) is obtained by the above method, and the target light quantity L is obtained at the next power-on. A drive current I ₀ ′ capable of emitting _zero laser light is calculated.

If at least two locations measurement data for generating the current light quantity characteristic enough, for example, be a point-to-point threshold current I _th and the endoscope during use amount.
Then, when prompted the gradient a and the threshold current _{I th,} by fitting the equation (1), the laser light source 8a after deterioration, 8b, by 8c, a drive current _{I 0} for achieving the target light quantity _{L 0} ' Can be calculated.

After the power is turned on again, the

laser light sources

8a, 8b, and 8c are driven by the drive current I ₀ ′ (step S4), so that the laser light with the target light amount can always be output and the deterioration of the image quality can be prevented. it can.
The amount of laser light emitted from a plurality of

laser light sources

8a, 8b, and 8c having different wavelength ranges has a constant light amount ratio in order to obtain illumination light of a desired color, but the

laser light sources

8a, 8b, By determining a target light amount for each laser source 8c, generating a current light amount characteristic for each of the

laser light sources

8a, 8b, and 8c, and obtaining a drive current that can achieve the target light amount for each of the

laser light sources

8a, 8b, and 8c, The ratio can be kept constant.

In this embodiment, in FIG. 2, the current control unit 12 is used by using a process of gradually decreasing the laser light amount after the use of the endoscope and before the laser light emission is completely stopped. Thus, the current light quantity characteristic is generated by storing the drive current input to each of the

laser light sources

8a, 8b, and 8c and the light quantity detected by the light quantity detector 11 in association with each other. Instead, the amount of light change when the drive current is decreased by one step (for example, 10 mA step) is equal to the amount of light change when the drive current is increased by one step, as shown in FIGS. As shown in the figure, after the endoscope is used, only the amount of change in the amount of light when the drive current is decreased by one step is measured and stored, and the drive current is increased by one step when the endoscope is used next time. The light amount may be increased within a range not exceeding the initial target light amount.

That is, when the endoscope is used next time, the control unit 17 uses the data sets (I ₀ , L ₀ ), (I ₁ , L ₁ ) and (I ₂ , L ₂₎ reads (step S1), and calculates a light amount change amount [Delta] L ₌ L 1 -L ₂ when the driving current was reduced by 1 step [Delta] I ₌ I 1 -I ₂ (step S5), and the driving current 1 It is determined whether or not the light amount L ₁ ′ = L ₁ + ΔL when increased by step ΔI does not exceed the initial target light amount L ₀ (step S6), and if not, the light amount L ₁ ′ is achieved. The drive current may be set to a possible current I ₀ ′ = I ₁ + ΔI (step S3), and the new target light amount L ₀ may be updated (step S7). Thereby, the calculation load in the control part 17 can be reduced.

Further, the current light quantity characteristic may be measured in the process of gradually increasing the light quantity immediately before the emission of laser light for use with an endoscope. Thereby, there is an advantage that the drive current can be controlled based on the immediately preceding light amount, and the light amount can be adjusted more accurately.

Further, the current light quantity characteristic may be measured when the light quantity falls below a predetermined level, for example, when it is reduced by 10%. If the fluctuation is within the range, an appropriate image quality can be obtained, and the current change frequency is low, so that the deterioration of the

laser light sources

8a, 8b, and 8c can be further reduced. Alternatively, the measurement may be performed periodically at regular intervals, for example, every 500 hours.

Further, when the exit end 5a of the single mode fiber 5 is spirally moved from the center toward the outer periphery (outward path) and moved from the outer periphery toward the center (return path) at the photographing frame rate, FIG. 7 and FIG. As shown in FIG. 8, when photographing is performed using one of the forward and return periods, and the

laser light sources

8 a, 8 b, and 8 c are turned off during the other period, the

laser light sources

8 a, 8 b, and 8 c that are being photographed are used. The current light quantity characteristic may be measured either when the

laser light source

8a, 8b, or 8c is changed from the OFF state to the ON state. The amount of light can be adjusted with high frequency, and fluctuations in the amount of light can be suppressed.

In the present embodiment, in all the

laser light sources

8a, 8b, and 8c, the drive current is increased so as to return to the initial target light amount, so that the light amount and the light amount even if the

laser light sources

8a, 8b, and 8c deteriorate. Although the case where both of the ratios are continuously maintained has been described, instead of this, as shown in FIG. 9, the change of the target light amount may be allowed and only the light amount ratio may be maintained constant.

That is, if the light amount is kept constant even if the

laser light sources

8a, 8b, and 8c are deteriorated, the drive current input to the

laser light sources

8a, 8b, and 8c becomes excessive when the deterioration becomes large. , 8b, 8c may be accelerated. Therefore, keeping the light quantity constant is effective when the degree of deterioration is relatively slow and small.

Instead, when the

laser light sources

8a, 8b, and 8c are turned off, the

laser light sources

8a, 8b, and 8c in which the light amount detected by the light amount detection unit 11 has been reduced most greatly are used as a reference. For the

light sources

8a, 8b, and 8c, the drive current may be set so that the light quantity ratio is constant.

As shown in FIG. 9 and FIG. 10, the amount of laser light from the laser light source 8b in the G wavelength region is greatly reduced, so that the light from the laser light source 8b in the G wavelength region at the end of use of the endoscope is reduced. The amount of laser light is stored. Further, the light quantity ratio of RGB and the current light quantity characteristic of each

laser light source

8a, 8b, 8c are stored.

When the use of the endoscope is resumed, the control unit 17 reads the stored data (step S1), and the stored laser light source 8b in the G wavelength range at the end of the use of the endoscope. Based on the stored RGB light quantity ratio, the target light quantity of the laser light from the

laser light sources

8a and 8c in the RB wavelength region is calculated (step S8). Thereafter, based on the obtained RGB target light amount and the stored current light amount characteristic, a drive current that can achieve the light amount of the laser light from each of the

laser light sources

8a, 8b, and 8c is calculated. Good (step S9).

In this way, by setting the target light quantity when resuming the use of the endoscope to be low in accordance with the

laser light sources

8a, 8b, 8c having the greatest deterioration, the drive current is kept low, and the

laser light sources

8a, 8b, It is possible to prevent the progressive deterioration of 8c. Further, since the light quantity ratio is kept constant, there is an advantage that the hue of the image can be kept unchanged.

In addition, as described above, the amount of light is kept constant until the deterioration becomes large and the drive current exceeds a predetermined threshold value. May be held constant.
That is, as shown in FIG. 11, when the use of the endoscope is resumed, the control unit 17 reads the stored data (step S1), calculates the coefficient of equation (1), and calculates the target light amount. A drive current I ₀ ′ capable of achieving L ₀ is calculated (steps S2 and S3). It is determined whether or not the calculated drive current I ₀ ′ exceeds a predetermined threshold (step S10).

If the calculated drive current I ₀ ′ does not exceed the predetermined threshold, the

laser light sources

8a, 8b, and 8c are driven with the calculated drive current I ₀ ′ (step S4), and the drive current I ₀ When ′ exceeds a predetermined threshold, the control unit 17 stores the light amount of the laser light from the laser light source 8b in the G wavelength region at the end of use of the stored endoscope as a reference. Based on the RGB light quantity ratio, the target light quantity of the laser light from the

laser light sources

8a, 8b, and 8c is calculated. Good (step S9).

In this embodiment, instead of setting the target light amount to a fixed value as shown in FIG. 2, the target light amount is set by a function that decreases with time as shown in FIG. Also good. The process is performed in the same manner as in FIG. 4, and the target light amount reduction line is used in the process of calculating the drive current I ₀ ′ in step S3.

That is, the target light quantity reduction line is defined as a function in which the target light quantity decreases with time. In the example shown in FIG. 12, it is a linear function in which the light quantity reduction rate is constant. The function of the target light quantity reduction line is a function that allows light quantity degradation within a range that does not significantly affect the image quality, for example, 30% light quantity reduction after 5000 hours.

In the present embodiment, the function is a function that gradually decreases rather than a decrease in light amount due to actual deterioration of the

laser light sources

8a, 8b, and 8c, and the target light amount is not returned to the initial value, but slightly lower than that. By returning to the value, it is possible to prevent an excessive increase in the drive current input to the

laser light sources

8a, 8b, and 8c and to prevent the deterioration from being accelerated. As a result, there is an advantage that the lifetime of the

laser light sources

8a, 8b, and 8c can be extended without affecting the image quality.

1 Scanning endoscope 5 Single mode fiber (optical fiber)
5a Ejection end 6

Scanner

8a, 8b, 8c Laser light source 10 Light source part (laser light source part)
11 Light quantity detection part 12 Current control part 17 Control part (characteristic generation part, target light quantity setting part)

Claims

A laser light source unit;
A current control unit for controlling the drive current of the laser light source unit;
An optical fiber that guides laser light emitted from the laser light source unit;
A scanner that vibrates the emission end of the optical fiber and scans the laser light emitted from the emission end in a two-dimensional manner;
A light amount detection unit for detecting a light amount of the laser light emitted from the laser light source unit;
A characteristic generation unit that generates a current light amount characteristic that associates the light amount detected by the light amount detection unit with the drive current input to the laser light source unit by the current control unit;
The scanning endoscope in which the current control unit controls the drive current so as to obtain a target light amount based on the current light amount characteristic generated by the characteristic generation unit.
The laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges,
The characteristic generation unit generates the current light quantity characteristic for each laser light source,
The scanning endoscope according to claim 1, wherein the target light amount of each laser light source is a fixed value having a predetermined light amount ratio.
The laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges,
The characteristic generation unit generates and updates the current light quantity characteristic for each laser light source,
The current light quantity characteristic before update with respect to any one of the laser light sources having a predetermined light quantity ratio as the target light quantity of each of the laser light sources and having the greatest decrease in the light quantity detected by the light quantity detection unit The scanning endoscope according to claim 1, further comprising: a target light amount setting unit configured to set the light amount achievable by the current light amount characteristic after the update by the driving current that achieves the target light amount before the update.
The laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges,
The characteristic generation unit generates and updates the current light quantity characteristic for each laser light source,
The target light amount of each laser light source has a predetermined light amount ratio and is fixed when the drive current that achieves the target light amount before update by the updated current light amount characteristic is equal to or less than a predetermined threshold. When the value exceeds the threshold value, the target before update is updated by the current light quantity characteristic before update for any one of the laser light sources detected by the light quantity detection unit with the greatest decrease in the light quantity. The scanning endoscope according to claim 1, further comprising a target light amount setting unit configured to set the light amount that can be achieved by the updated current light amount characteristic by the driving current that achieves the light amount.
The laser light source unit includes a plurality of laser light sources that respectively emit the laser beams having different wavelength ranges,
The characteristic generation unit generates and updates the current light quantity characteristic for each laser light source,
2. The scanning endoscope according to claim 1, further comprising a target light amount setting unit that has a predetermined light amount ratio as a target light amount of each of the laser light sources and sets a predetermined function that decreases with time.
The target light quantity setting unit sets a target light quantity that is larger than the light quantity that can be achieved by the updated current light quantity characteristic by the drive current that achieves the target light quantity before update by the current light quantity characteristic before update. Item 6. The scanning endoscope according to Item 5.
The scanning endoscope according to any one of claims 2 to 6, wherein the characteristic generation unit generates the current light quantity characteristic at a predetermined timing.