JP2010042153A - Illumination device and endoscope using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device for stably obtaining illumination light without a noise of speckle interference at any time and an endoscope using this. <P>SOLUTION: In the illumination device which includes a light source 65 for emitting light of a first wavelength band and a fluorescent body 69 which excites and emits light of a second wavelength band by the light of the first wavelength band and obtains the illumination light by mixing the light of the first and second wavelength bands, the light source 65 is a laser diode of a broad area type, and a high-frequency wave superimposing means 59 for making the laser diode undergo multimode oscillations by superimposing a high-frequency signal on a driving current supplied to the laser diode is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an illumination device that uses a broad area semiconductor laser as a light source and excites a phosphor to emit light and an endoscope using the same.

An endoscope apparatus that has been widely used conventionally guides light from a lamp in a light source device by a light guide provided along an endoscope insertion portion, and the illumination light guided by the light guide. It is configured to illuminate the inspection target site by emitting from the illumination window at the tip of the endoscope insertion portion. On the other hand, there is one that performs illumination using a laser light source instead of a lamp. For example, the illumination device of Patent Document 1 guides light emitted from a blue semiconductor laser to the tip of an endoscope insertion portion by an optical fiber, excites a phosphor disposed at the tip of the optical fiber, and inspects white illumination light obtained thereby. It is the structure which irradiates a target part. According to this illuminating device, the thinness of the light guide path required for the endoscope and the brightness of the illumination light can both be achieved.
However, it is known that mode hopping noise, return light noise, and speckle noise on the irradiated surface are generated as intensity noise in a semiconductor laser. When a semiconductor laser is used, a phenomenon in which a spot-like noise pattern is oscillated on the irradiated surface particularly occurs according to the uneven shape of the irradiated surface. This is due to speckle interference, and this minute fluctuation can hinder the observation of the affected area when illumination light is used for an endoscope or the like. Since speckle interference is caused by oscillation at a single wavelength, in order to weaken this, the longitudinal mode is changed to multimode (multimode) and the coherence of the laser light is weakened (Cited document 2). reference).
JP 2005-205195 A JP 2002-95634 A

However, when a transverse mode single mode laser with a narrow emission width is used as in Cited Document 2, since the original coherence is high, noise due to speckle interference is sufficiently reduced even if the longitudinal mode is changed to multimode. Can not. Further, in order to obtain white light, a laser light source corresponding to the number of primary colors is required, which increases the cost and inevitably increases the size of the apparatus.
In order to suppress speckle interference, there is a method using a self-excited oscillation type (self-pulsation) laser. However, when it is used for general purpose or an endoscope illumination device such as an upper or lower digestive tract, The demand for high output is high, and it is difficult to cope with semiconductor laser elements. Furthermore, laser light that has been converted to multimode by a gain-guided multimode laser can also be used, but the operating current is larger than that of single-mode lasers and self-excited light-emitting lasers. There is a disadvantage that competition noise between a plurality of transverse modes becomes high.
In addition, there is a method using a refractive index guided multimode laser, but since the number of transverse modes is reduced compared to the gain guided type, the transverse mode competitive noise is reduced, which is preferable, but conversely, the transverse modes are limited. As a result, the number of longitudinal modes also decreases, and there arises a problem that speckle noise increases due to improved spectral purity.
The present invention has been made in view of such a situation, and an object of the present invention is to provide an illuminating device that can stably obtain illuminating light without speckle interference and an endoscope using the illuminating device.

The present invention has the following configuration.
(1) a light source that emits light in the first wavelength band; and a phosphor that excites and emits light in the second wavelength band with the light in the first wavelength band, and the first wavelength band and An illumination device that obtains illumination light by mixing light of the second wavelength band,
The light source is a broad area type semiconductor laser;
An illumination device comprising high-frequency superimposing means for superimposing a high-frequency signal on a drive current supplied to the semiconductor laser to oscillate the semiconductor laser in a multimode.

  According to this illuminating device, a longitudinal mode is converted into a multimode by applying a driving current superimposed with a high-frequency signal to a broad area type semiconductor laser having a plurality of transverse modes. However, since the transverse mode changes with respect to the time axis, it is possible to always stably emit light that is unlikely to cause speckle interference. This can prevent speckle noise from occurring in the illumination area.

(2) The lighting device according to (1),
A condensing lens that condenses the light in the first wavelength band;
The light collected by the condenser lens is incident on one end side and is emitted from the other end side, and
An illuminating device in which the phosphor is disposed on a light emitting side of the optical fiber.

  According to this illumination device, laser light is introduced from one end of an optical fiber by a condensing lens and irradiated to a phosphor disposed on the other end of the optical fiber, thereby suppressing diffusion of high-intensity light with high efficiency. Can be propagated. In addition, since the light guide path can be formed of a thin optical fiber, it is easy to reduce the diameter of the light guide path, and the configuration of the lighting device can be simplified.

(3) The illumination device according to (1) or (2),
A lighting device comprising a changeover switch for controlling whether or not the high frequency signal is superimposed on a drive current by the high frequency superimposing means.

  According to this illumination device, the type of illumination light can be manually switched at an arbitrary timing, and usability can be improved.

(4) The illumination device according to any one of (1) to (3),
An illumination device in which the light source emits blue light as light in the first wavelength band.

  According to this illumination device, by emitting blue laser light, a general down-conversion phosphor can be used, and the degree of freedom in selecting the phosphor material is increased.

(5) The illumination device according to any one of (1) to (4),
The phosphor mixes the light in the first wavelength band and the light in the second wavelength band by transmitting a part of the light in the first wavelength band while diffusing in the phosphor. Lighting device.

  According to this illuminating device, illumination light with a more uniform distribution can be obtained by diffusing the laser light in the first wavelength band with high straightness by the phosphor.

(6) An endoscope for observing the inside of a subject by inserting an endoscope insertion portion into the subject,
The illumination device according to any one of (1) to (5), which illuminates the inside of the subject;
An endoscope having imaging means for imaging the illuminated subject and generating image information.

  According to this endoscope, it is possible to irradiate the subject with illumination light that is always stable and free of speckle interference. Therefore, it is possible to obtain a picked-up image with less noise for an observation site in the subject.

(7) The endoscope according to (6),
First imaging information obtained by imaging an observation image with illumination light when the high-frequency signal is superimposed on the driving current and illumination light when the high-frequency signal is not superimposed on the driving current. An endoscope that outputs second image information obtained by capturing an observation image.

  According to this endoscope, image information when the high-frequency signal is superimposed and not superimposed on the drive current is output, the state of the observation site can be grasped more accurately from both images, and the diagnostic accuracy is improved.

(8) The endoscope according to (7),
An endoscope comprising image display means for simultaneously displaying the first image information and the second image information in different display areas.

  According to this endoscope, both pieces of image information can be observed simultaneously, and the state of the observation site can be grasped quickly and easily.

(9) The endoscope according to (8),
An endoscope in which the image display means alternately displays the first image information and the second image information at an imaging frame period of the imaging means.

  According to this endoscope, the image information can be confirmed in real time by alternately switching and displaying both pieces of image information.

  According to the illumination device of the present invention and the endoscope using the same, the longitudinal mode is changed to the multimode by applying the driving current superimposed with the high frequency signal to the broad area type semiconductor laser having a plurality of transverse modes. In addition, since each of the plurality of transverse modes has a wavelength spread, and the transverse mode changes with respect to the time axis, it is possible to always stably emit light that is unlikely to cause speckle interference. . This can prevent speckle noise from occurring in the illumination area.

Hereinafter, a preferred embodiment of an illumination device and an endoscope using the same will be described in detail with reference to the drawings.
First, the configuration of the endoscope will be described.
FIG. 1 is a configuration diagram of an endoscope system representing an endoscope and devices to which the endoscope is connected, and FIG. 2 is a block configuration diagram of the endoscope system of FIG.
As shown in FIG. 1, the endoscope system 11 mainly includes an endoscope 100, a light source device 13, a processor 15 that performs imaging signal processing, and a monitor 17. The endoscope 100 includes a main body operation unit 19 and an insertion unit 21 that is connected to the main body operation unit 19 and is inserted into a subject (body cavity). A universal cable 23 is connected to the main body operation unit 19, and a distal end of the universal cable 23 is connected to the light source device 13 via a light guide (LG) connector 25. The imaging signal is input to the processor 15 via the video connector 31.

The main body operation unit 19 of the endoscope 100 is provided with buttons for performing suction, air supply, and water supply on the distal end side of the insertion unit 21 and various operation buttons 27 such as a shutter button during imaging. A pair of angle knobs 29A and 29B are provided.
The insertion portion 21 is composed of a flexible portion 33, a bending portion 35, and a distal end portion 37 in order from the main body operation portion 19 side. The bending portion 35 is remotely controlled by rotating the angle knobs 29A and 29B of the main body operation portion 19. Bending operation. Thereby, the front-end | tip part 37 can be orient | assigned to a desired direction.

As shown in FIG. 2, an observation window 41 of the imaging optical system and a light irradiation window 43 of the illumination optical system are disposed at the distal end portion 37 of the endoscope 100, and illumination irradiated from the light irradiation window 43. The reflected light from the subject by light is imaged through the observation window 41. The captured observation image is displayed on a monitor 17 connected to the processor 15.
Here, the imaging optical system includes an imaging element 45 such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and an optical member such as an imaging lens 47. An observation image captured by the image pickup optical system is formed on the light receiving surface of the image pickup device 45 and converted into an electric signal, and the electric signal is input to the image pickup signal processing unit 51 of the processor 15 through the signal cable 49, where the image is displayed. Converted to a signal.

On the other hand, the illumination optical system includes a light source device 13 having a laser light source unit 55, an optical fiber 53 connected thereto, and a wavelength conversion unit 57 disposed on the light emitting side of the optical fiber 53. The optical fiber 53 is an optical fiber cable having a central core layer and an outer cladding layer. The optical fiber 53 guides laser light to the distal end portion 37 of the endoscope 100, and emits white illumination light from the wavelength converting portion 57 of the distal end portion 37. Is generated. The wavelength converter 57 includes a phosphor that emits light by excitation with laser light. The laser light source unit 55 receives a drive signal from the light source drive circuit 59 based on a command from the control unit 61 and emits laser light.
The control unit 61 is also connected to a memory 63 that stores an image pickup signal, and displays image data output from the image pickup signal processing unit 51 on the monitor 17 or is connected to a network such as a LAN (not shown) and includes image data. The entire endoscope system 11 is controlled such as distributing information.

As shown in the block diagram schematically showing the illumination optical system in FIG. 3, the laser light source unit 55 includes a blue-emitting broad area semiconductor laser (hereinafter referred to as a blue laser light source) 65 having a central wavelength of 445 nm, And a condensing lens 67 that condenses the laser light from the blue laser light source 65. In the semiconductor laser, the shorter the wavelength of the emitted light, the smaller the active region (stripe) width that becomes a single mode. In the case of a blue semiconductor laser, the active region width is a single mode condition of 1 to 2 μm. Accordingly, a laser having an active region width of 3-6 μm or more, which is several times the width, can be called a broad area type semiconductor laser. In other words, the broad area type semiconductor laser in this specification is defined as having an active region width of, for example, 3 to 6 μm or more (for example, 5 μm or more, 50 μm or less), as distinguished from a narrow stripe semiconductor laser having a narrow active region width. To do.
If the wavelength of the emitted light is on the order of 400 nm (405 nm, 445 nm, etc.), it can be set to 50 μm or less as described above from a practical viewpoint. However, the upper limit of this active region width is the current nitride crystal growth About 50 μm means the limit because of the technology and the high non-uniformity in the selected substrate surface orientation, and not the theoretical limit. For example, some arsenic phosphorous laser diodes having a wavelength of 780 nm used for blood vessel navigation have an active region width of 200 μm.

The blue laser light source 65 emits blue laser light while controlling the amount of emitted light, and this emitted light is irradiated to the wavelength conversion unit 57 of the endoscope insertion unit 21 through the optical fiber 53.
The wavelength converter 57 absorbs a part of the laser light from the blue laser light source 65 and emits a plurality of types of phosphors 69 (for example, YAG phosphors, BMA (BaMgAl ₁₀ O ₃₇ ), etc. that emit light in green to yellow. Etc.). Thereby, the laser light from the blue laser light source 65 and the green to yellow excitation light converted from the laser light are combined to generate white light.

  As the blue laser light source 65, a broad area type InGaN laser diode can be used. Further, although not shown, the optical fiber 53 is fixed to the distal end hard portion (metal block) of the endoscope insertion portion 21 with the optical axis aligned through a fixing jig. The fixing jig fixes the phosphor 69 on the light emitting side of the optical fiber 53, and emits the excited light emitted by receiving the light emitted from the optical fiber 53 to the front of the optical path. At this time, the blue laser light component transmitted through the phosphor 69 without wavelength conversion is diffused by the phosphor 69 and has a diffusion angle of 60 ° to 70 ° with respect to the optical axis from the laser beam having high straightness. It is emitted as diffused light.

FIG. 4 is a graph showing the spectral distribution of light after blue laser light has been wavelength-converted by the phosphor.
The blue laser light from the blue laser light source 65 is represented by a bright line having a central wavelength of 445 nm, and the emission intensity is increased in a wavelength band of approximately 450 nm to 700 nm by light emitted from the phosphor 69 by the laser light. White light is formed by the light of this wavelength band and the blue laser light.

Next, a drive circuit for the blue laser light source of the illumination optical system having the above configuration will be described.
The blue laser light source 65 is connected to a direct current source 71 that supplies a direct current drive current via an inductor 73, and an oscillator 75 that superimposes a sinusoidal high frequency signal on the drive current from the direct current source 71. They are connected via a coupling capacitor 77. This high-frequency signal is a sine wave signal that can be set arbitrarily in the range of several hundred to several thousand MHz, and the vertical mode of the blue laser light source 65 is converted into a multimode by being superimposed on the drive current. In the above configuration, the inductor 73 exhibits a high impedance for a high-frequency signal from the transmitter 75 and a low impedance for a drive current. Further, the coupling capacitor 77 removes a direct current component from the high frequency signal from the transmitter 75. That is, the transmitter 75 functions as a high-frequency superimposing unit that superimposes the high-frequency signal on the drive current to cause the blue laser light source 65 to oscillate in multiple modes.

FIG. 5 is a graph showing an example of the drive current by the light source drive circuit shown in FIG. 3, and FIG. 6 is a graph showing the relationship between the light output intensity with respect to the drive current of the blue laser light source.
As shown in FIG. 5, the drive current is obtained by superimposing the high-frequency signal from the transmitter 75 on the bias current from the DC current source 71. When this drive current is applied to the blue laser light source 65, as shown in FIG. 6, when the drive current changes, multimode (relaxation oscillation) occurs during the transient response of the laser oscillation, thereby increasing the light output intensity. Change. Such a disturbance with respect to the time axis reduces the coherence and can reduce the occurrence of speckle interference in the laser light irradiation region. This method is effective regardless of whether the blue laser light source 65 is the horizontal single mode or the multi mode.

In addition, the broad area semiconductor laser has a wide emission width and a plurality of transverse modes. Each of the plurality of transverse modes has different wavelength band components of higher order modes centered on the fundamental oscillation frequency f ₀ , as shown in FIG. It has a predetermined wavelength spread. The increase in the transverse mode and the spread of the emission wavelength can reduce the occurrence of speckle interference in the laser light irradiation region.

In other words, the blue light emitted from the blue laser light source 65 disturbs a plurality of transverse modes with respect to the time axis by superimposing high-frequency signals, and generates white noise. As a result, the wavelength also changes in the transverse mode. In response to the change, the coherence of the laser beam is lowered. Thereby, generation | occurrence | production of a speckle interference can be reduced.
In addition, the lateral mode of the broad area type semiconductor laser has different optical coupling efficiency for each mode when the optical fiber 53 is condensed by the condenser lens 67. Transverse mode variations may occur. At that time, the output fluctuation of the laser beam occurs, but in this configuration, since each mode is used in a state of being excited uniformly, even if the transverse mode fluctuation occurs, the output fluctuation of the laser beam can be suppressed to a small level.
In addition, when a phosphor is excited, a broad area type semiconductor laser can modulate the transverse mode by superposition of a high frequency signal, so that the output is stabilized with respect to time, and occurs at a relatively slow number of several kHz. The intensity noise that has been reduced is reduced, and a stable image can be acquired.

  In this way, by applying a driving current superimposed with a high frequency signal to the broad area type blue laser light source 65 having a plurality of transverse modes, the longitudinal mode is converted into a multimode, and each of the plurality of transverse modes is Since it has a broadened wavelength and the transverse mode changes with respect to the time axis, it is possible to always stably emit light that is unlikely to cause speckle interference. This can prevent speckle noise from occurring in the illumination area.

Next, an effect of reducing speckle interference when the modulation frequency of the blue laser light source 65 is changed by the light source driving circuit 59 will be described.
FIG. 8 shows a graph showing the state of speckle noise with respect to the modulation frequency when photographing the white color of the Macbeth chart. In the figure, the horizontal axis represents the modulation frequency by the light source drive circuit 59, and the vertical axis represents the root mean square value (RMS value) of the pixel value of the acquired image. Here, the amplitude of the modulation is in the range of 0 to 100%, and the duty ratio is 50%. The pixel value is a 16-bit value for each color of RGB, and the QL maximum value (maximum quantization level) is 65416.

In a full color image captured without modulating the blue laser light source 65, speckle noise of about 4000 is generated as an RMS value, and easily visible random noise is superimposed. The generation of speckle noise is caused by blue laser light as excitation light. When only a blue component is extracted from a full-color image, speckle noise appears remarkably.
On the other hand, when the blue laser light source 65 is modulated at 1 kHz, the RMS value of the captured full-color image is reduced to about 3500, and the light quantity distribution is uniform in terms of time and space. Will not be visible. When the modulation frequency is 1 kHz or more, the change in the RMS value with respect to the modulation frequency tends to decrease and converge to a predetermined value (3500 in the illustrated example), and about 1 kHz is sufficient to reduce speckle noise. An effect is obtained.

  The speckle noise starts to decrease from 100 Hz, but the imaging cycle of the endoscope image sensor is, for example, 1/30 to 1/60 seconds. Therefore, when the modulation frequency is about 100 Hz, Appears as "flicker". If the modulation amplitude is reduced, “flickering” can be prevented, but in that case, speckle noise appears. For example, when the modulation amplitude is 100%, an image having no flicker and no speckle noise is obtained when the modulation frequency is 500 Hz or higher. When the modulation frequency is 1 kHz or more, the effect is further increased. Even when the modulation amplitude is lowered by about 10 to 20%, the generation of speckle noise is suppressed, and a more stable noise reduction effect can be obtained.

  Further, when increasing the amount of light of the light source, for example, in an examination endoscope, it is necessary to increase the output of the laser diode. In this case, the drive current increases. However, in order to drive a large drive current with a modulation amplitude of 100%, the requirement for matching accuracy of the circuit increases, and the cost of the power supply increases. In such a case, it is effective to further increase the modulation frequency or decrease the modulation amplitude. In the above items, the pulse waveform is not limited to a square pulse, and may be a sine wave, a sawtooth wave, or a triangular wave. Further, the same effect can be obtained by sweeping the pulse frequency from 100 Hz to several hundreds and several kHz within the charge accumulation time of the imaging period (1/30 to 1/60 seconds) of the endoscope.

Next, a usage example of the endoscope system 11 in which the illumination optical system having the above configuration is incorporated in the endoscope 100 will be described.
When inserting the insertion part 21 of the endoscope 100 shown in FIGS. 1 and 2 into a subject (body cavity) and emitting white illumination light from the distal end of the insertion part 21, high-frequency signal superposition and high-frequency superposition are performed. The imaging signal obtained by imaging in each case can be switched to the case where it is not performed, and is captured in the memory 63 shown in FIG. 2 and subjected to appropriate image processing by the imaging signal processing unit 51 and displayed on the monitor 17. Alternatively, it is stored in a recording medium.

For example, in the case where observation is performed by irradiating white illumination light in the subject with the endoscope 100, at the time of normal endoscope diagnosis, the control unit 61 uses the light source drive circuit 59 shown in FIG. A drive current superimposed with a high frequency signal is applied to 65 to emit blue laser light. This blue laser light has low coherence, and the white light with less speckle noise is generated by mixing the fluorescence converted in wavelength by the phosphor 69 and the diffused light diffused and passed by the phosphor 69. To do.
When the controller 61 stops superimposing the high-frequency signal from the transmitter 75 of the light source driving circuit 59 on the driving current, illumination light with speckle noise is generated. The illumination light in this case can be obtained as an image in which the concavo-convex shape of the imaged observation surface is further emphasized by performing image enhancement processing especially on the blue component (blue laser light component) of the captured image data.

Therefore, the control unit 61 can selectively obtain image information suitable for the observation purpose from the subject by controlling whether or not the high-frequency signal is superimposed on the drive current at an appropriate timing.
FIG. 9 is an explanatory diagram conceptually showing a plurality of frame images (a) obtained in time series by imaging with the imaging optical system and a state (b) of classifying these frame images. Here, control is performed to display an observation image under illumination light with white light with little speckle noise and an observation image under illumination light with a lot of speckle noise at different display positions on the monitor 17, respectively. .
As shown in FIG. 9A, the control unit 61 controls the emission of the illumination light of the illumination optical system, and in the first frame at the time of moving image capturing, the drive current superimposed with the high-frequency signal is applied to the blue laser light source. Applying to 65, blue laser light having a central wavelength of 445 nm is emitted, and the subject is irradiated with white light with little speckle noise. The imaging element 45 images the subject illuminated with the white light and stores the imaging signal in the memory 63 (see FIG. 1).

  Next, the control unit 61 controls the emitted light by the illumination optical system, and in the second frame, applies a drive signal on which the high-frequency signal is not superimposed to the blue laser light source 65 to include a lot of speckle noise. An object is irradiated with white light. The subject illuminated with the white light is imaged, and the imaging signal is stored in the memory 63. This imaging signal is subjected to a blue component enhancement process.

  Thereafter, similarly, the third frame (odd frame) repeats the processing of illumination / imaging / image signal storage in the same manner as the first frame in the third frame (odd frame) and the second frame in the fourth frame (even frame). . That is, the illumination of white light with little speckle noise and the illumination of white light with much speckle noise are switched alternately for each imaging frame of the imaging device 45.

  Then, as illustrated in FIG. 9B, the memory 63 stores an illumination image with white light with little speckle noise and an enhancement processing image of the illumination image with white light with much speckle noise. Image information based on these two types of imaging signals is displayed in different display areas 78 and 79 in the display surface of the monitor 17, as shown in FIG. The sizes of the display areas 78 and 79 are the same in the illustrated example, but either one is displayed larger than the other, or the other image is overlapped and displayed smaller in either image display area. Etc., can be set arbitrarily.

  As described above, the normal image by normal white illumination and the enhanced image with the concavo-convex shape enhanced are simultaneously displayed on the same screen, so that the state of the observation site can be grasped quickly and easily. In addition, since each piece of image information can be observed in real time, accurate image information can be recognized, and diagnostic accuracy can be further improved.

  Further, white illumination light with little speckle noise and white illumination light with a lot of speckle noise can be switched by a simple hand operation by the changeover switch 81 provided on the main body operation unit 19 of the endoscope 100. It is good also as composition to do. In this case, the illumination light can be manually switched at an arbitrary timing, and usability can be improved.

According to the endoscope 100 described above, by using laser light as a white light source of the illumination optical system, the endoscope 100 can be guided by the optical fiber 53, and high-intensity light can be inserted with high efficiency while suppressing diffusion. It can be propagated to the tip of the part 21. Further, since the white light guide path can be constituted by an optical fiber, it is easy to reduce the diameter of the endoscope insertion portion without requiring a conventional large-diameter light guide (optical fiber bundle). That is, in order to guide the amount of light required for the illumination of the endoscope to the distal end of the insertion portion 21 of the endoscope 100, the diameter of the light guide is required to be at least about 1 mm. In the configuration of the embodiment, the outer diameter including the protective material for the outer skin can be as small as about 0.3 mm.
In addition, said illuminating device and the endoscope 100 using the same are not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. For example, the illumination may be performed by merging laser light that does not excite the phosphor into the optical path. Moreover, it is good also as a structure which provided the diffuser plate in the light emission part of the front-end | tip part of the endoscope 100, and strengthened the diffusibility of illumination light.

It is a lineblock diagram of an endoscope system showing each apparatus to which an endoscope and an endoscope are connected. It is a block block diagram of the endoscope system of FIG. It is a block diagram showing the illumination optical system schematically. It is a graph which shows the spectrum distribution of the light after blue laser light is wavelength-converted by fluorescent substance. It is a graph showing an example of the drive current by the light source drive circuit shown in FIG. It is a graph showing the relationship with the optical output intensity with respect to the drive current of a blue laser light source. It is a graph which shows the oscillation waveform with respect to a wavelength. It is a graph which shows the state of the speckle noise with respect to the modulation frequency when image | photographing the white of a Macbeth chart. It is explanatory drawing which shows notionally the several frame image (a) obtained in time series by the imaging by an imaging optical system, and a mode (b) which classifies these frame images. It is explanatory drawing which shows a mode that the illumination image by the white light with few speckle noises and the enhancement process image of the illumination image by the white light with many speckle noises were each displayed on the different display area in the display surface of a monitor. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Endoscope system 13 Light source device 15 Processor 17 Monitor 19 Main body operation part 21 Insertion part 27 Operation button 41 Observation window 43 Light irradiation window 45 Imaging element 47 Imaging lens 49 Signal cable 51 Imaging signal processing part 53 Optical fiber 55 Laser light source part 57 wavelength conversion unit 59 light source drive circuit 61 control unit 65 blue laser light source 67 condenser lens 69 phosphor 71 direct current source 73 inductor 75 transmitter 78, 79 display area 81 changeover switch 100 endoscope

Claims (9)

A light source that emits light in the first wavelength band; and a phosphor that excites and emits light in the second wavelength band by the light in the first wavelength band, the first wavelength band and the second wavelength band. An illumination device that obtains illumination light by mixing light in the wavelength band of
The light source is a broad area type semiconductor laser;
An illumination device comprising high-frequency superimposing means for superimposing a high-frequency signal on a drive current supplied to the semiconductor laser to oscillate the semiconductor laser in a multimode. The lighting device according to claim 1,
A condensing lens that condenses the light in the first wavelength band;
The light collected by the condenser lens is incident on one end side and is emitted from the other end side, and
An illuminating device in which the phosphor is disposed on a light emitting side of the optical fiber. The lighting device according to claim 1 or 2,
A lighting device comprising a changeover switch for controlling whether or not the high frequency signal is superimposed on a drive current by the high frequency superimposing means. It is an illuminating device of any one of Claims 1-3, Comprising:
An illumination device in which the light source emits blue light as light in the first wavelength band. It is an illuminating device of any one of Claims 1-4, Comprising:
The phosphor mixes the light in the first wavelength band and the light in the second wavelength band by transmitting a part of the light in the first wavelength band while diffusing in the phosphor. Lighting device. An endoscope for observing the inside of a subject by inserting an endoscope insertion portion into the subject,
The illumination device according to any one of claims 1 to 5, which illuminates the inside of the subject;
An endoscope having imaging means for imaging the illuminated subject and generating image information. The endoscope according to claim 6, wherein
First imaging information obtained by imaging an observation image with illumination light when the high-frequency signal is superimposed on the driving current and illumination light when the high-frequency signal is not superimposed on the driving current. An endoscope that outputs second image information obtained by capturing an observation image. The endoscope according to claim 7, wherein
An endoscope comprising image display means for simultaneously displaying the first image information and the second image information in different display areas. The endoscope according to claim 8, wherein
An endoscope in which the image display means alternately displays the first image information and the second image information at an imaging frame period of the imaging means.