WO2013179962A1 - Light-source device - Google Patents

Abstract

In the present invention, the cross-section of a beam from a light-emitting element is shaped, with light-transmission losses reduced. [Solution] A light-source device (13) for an endoscope is provided with the following: a light-emitting-element part (71) that has a laser diode (LD2); and a light-source module that has a beam-shaping part (73). Said beam-shaping part (73) is a prism-shaped light-guiding rod, and the cross-section thereof perpendicular to an optical axis (A) is hexagonal. A substantially elliptical beam emitted by the laser diode (LD2) is shaped by the beam-shaping part (73) into a substantially circular shape. When a minor-axis component (RS) of the elliptical beam enters the beam-shaping part (73), said minor-axis component (RS) is guided in the direction of the optical axis (A), undergoing total internal reflection at the interior surface of a side face (73b) of the beam-shaping part (73). As the beam is being thus guided, since minor-axis components (RS) are incident upon sides of the hexagon at non-perpendicular angles, said minor-axis components (RS) are reflected at angles, causing rotation about the optical axis (A). Many of the light rays constituting the beam undergo such rotation, shaping the cross-section of the beam into a substantially circular shape.

Description

Light source device

The present invention relates to a light source device having a light emitting element.

A light source device having a light emitting element such as a laser diode is used in various fields. Patent Document 1 describes the use of a laser diode in a light source device for an endoscope.

As shown in FIG. 54, the laser diode LD is a light emitting element composed of a semiconductor and has a structure in which a P layer made of a P-type semiconductor, an active layer K, and an N layer made of an N-type semiconductor are stacked. The active layer K emits laser light. The laser light is divergent light that spreads in a substantially conical shape from the emission center OP. The laser diode LD also has a light emitting point that emits light that spreads in the horizontal direction (X direction) parallel to the active layer K and a light emitting point that emits light that spreads in the vertical direction (Y direction) perpendicular to the active layer. Since there is an astigmatism difference ΔAs in the optical axis direction, it is known that the cross-sectional shape of the light beam (beam) BM orthogonal to the optical axis becomes a vertically long substantially elliptical shape that is long in the Y direction. This means that the beams emitted from the laser diode LD have different divergence angles in the X direction corresponding to the short axis and the Y direction corresponding to the long axis.

Since the cross-sectional shape of the beam is reflected in the irradiation spot shape on the irradiated object, beam shaping is performed to shape the cross-sectional shape of the beam from a substantially elliptical shape to a substantially perfect circular shape when it is desired to make the irradiation spot shape a substantially circular shape. Done. The light source unit described in Patent Document 2 has two lenses, a coupling lens and a condenser lens. By arranging these two lenses on the optical path of the beam emitted from the laser diode LD, The beam shaping of the laser diode LD is performed.

The coupling lens is a lens that collimates and emits a beam having a divergence angle after collimating the beam once. In the coupling lens, the entrance surface and the exit surface are composed of two first and second cylindrical lens surfaces having different focal lengths. The first cylindrical lens surface has a refractive power only in the X direction corresponding to the short axis of the beam, and the second cylindrical lens surface has a refractive power only in the Y direction corresponding to the long axis of the beam. Since the first cylindrical lens surface and the second cylindrical lens surface have different focal lengths (because of their different refractive powers), they are corrected so that the divergence angles of the major axis and the minor axis of the beam coincide with each other due to the refractive action of each lens surface. Thus, the cross-sectional shape of the beam is shaped from a substantially elliptical shape to a substantially perfect circle. Since the beam emitted from the coupling lens is collimated, it is converted into a beam having a divergence angle by the condenser lens.

JP 2011-041758 A JP 2000-304993 A

However, as in the beam shaping technique described in Patent Document 2, when beam shaping is performed using the refraction action of a lens, the beam is once converted into parallel light by one lens, and another condenser lens. Therefore, there is a problem that the number of interfaces between the air and the lens increases, and the light transmission loss is large. As described in Patent Document 2, instead of using two lenses, a coupling lens having two cylindrical lens surfaces and a condensing lens that condenses parallel light emitted from the coupling lens, Even if two cylindrical lenses having a cylindrical lens surface for beam shaping formed on one surface are combined, beam shaping can be performed in the same manner. However, in this case as well, two beams are required because the beam is once collimated by one cylindrical lens and then converted into a beam having a divergence angle by another cylindrical lens. In fact, the problem of increased optical transmission loss cannot be solved. *

An object of the present invention is to provide a light source device capable of shaping the cross-sectional shape of a beam of a light emitting element while suppressing light transmission loss.

In order to achieve the above object, the light source device of the present invention includes a light emitting element and an optical element. The light emitting element emits a diverging beam, and the beam has different divergence angles in a first direction and a second direction orthogonal to the first direction in the cross section. The optical element has an incident surface on which a beam emitted from the light emitting element is incident, an exit surface that emits the incident beam, and a longitudinal axis that extends in a longitudinal direction from the incident surface toward the exit surface. It is an optical element that propagates in the longitudinal direction while being reflected internally, and has a reflective side surface that is oblique to at least one of the first and second directions of the beam on a plane orthogonal to the longitudinal axis.

The optical element twists around the optical axis by reflection at the reflection side surface with respect to at least one of the first component and the second component parallel to each of the first direction and the second direction among the light rays contained in the beam. It is preferable to make it occur.

It is preferable that the optical element is a light guide rod made of a columnar body formed of a transparent material, the reflection side surface is a boundary surface with air, and the reflection is total reflection.

In the optical element, for example, the cross-sectional shape orthogonal to the longitudinal axis is a polygon, and the reflection side surface is a flat surface. The polygon is, for example, any one of a hexagon, a quadrangle, and a triangle.

When the polygon is a hexagon, it is preferable that the optical element is arranged in a posture in which an axis connecting two opposite vertices of the hexagon is inclined with respect to the first direction or the second direction. The inclination angle of the axis with respect to the first direction or the second direction is, for example, 15 °.

In the case where the polygon is a quadrangle, the optical element is preferably arranged such that each side of the quadrangle is inclined with respect to a normal posture parallel to the first direction or the second direction. The inclination angle with respect to the normal posture is preferably 45 °.

The optical element is preferably arranged in a state where the center of the polygonal cross section coincides with the light emission center of the light emitting element.

In the optical element, the area of the incident surface may have such a size that light from a plurality of light emitting elements can enter. The optical element may have a tapered shape in which the reflection side surface is inclined with respect to the longitudinal axis.

The cross-sectional shape of the beam emitted from the light emitting element is, for example, an ellipse having a major axis and a minor axis corresponding to the first direction and the second direction, respectively, and the optical element is an elliptical beam incident on the incident surface. Is shaped into a perfect circle, for example, and emitted from the emission surface. Here, the oval shape includes a substantially oval shape in addition to a complete oval shape. Similarly, the true circle is not limited to a perfect true circle but includes a substantially perfect circle. The light emitting element is, for example, a laser diode.

A first light source unit that emits a beam having a true circular cross section without using an optical element, a light emitting element and an optical element, and emitting a beam having a true circular cross section shaped by the optical element. You may provide at least 2 types of light source parts of the 2nd light source part to do. The first light source unit includes, for example, a light emitting element and a phosphor that emits fluorescence when excited by light emitted from the light emitting element.

According to the present invention, it is possible to provide a light source device capable of shaping the cross-sectional shape of the light emitting element beam while reducing light transmission loss.

It is an external view of the endoscope system of the present invention. It is a front view of the front-end | tip part of an endoscope. It is a block diagram which shows the electric constitution of an endoscope system. It is a graph which shows the spectrum of illumination light. It is a graph which shows the absorption spectrum of hemoglobin. It is a graph which shows the scattering coefficient of a biological tissue. It is a graph which shows the spectral characteristic of the color microfilter of an image pick-up element. It is explanatory drawing which shows the irradiation timing of the illumination light in normal observation mode, and an imaging timing. It is explanatory drawing which shows the irradiation timing and imaging timing of the illumination light of the blood vessel emphasis observation mode. It is explanatory drawing which shows the irradiation timing and imaging timing of the illumination light in oxygen saturation observation mode. It is explanatory drawing which shows the image processing procedure in normal observation mode. It is explanatory drawing which shows the image processing procedure in blood-vessel emphasis observation mode. It is explanatory drawing which shows the image processing procedure in oxygen saturation observation mode. It is a perspective view of a branched light guide and a light source module. It is explanatory drawing of arrangement | positioning of the optical fiber in the output end of a branched light guide. It is explanatory drawing of a homogenizer. It is a perspective view of a 1st light source module. It is explanatory drawing of the divergence angle correction | amendment part of a 1st light source module. It is a perspective view of a 2nd light source module. It is a side view of the divergence angle correction | amendment part of a 2nd light source module. It is explanatory drawing of the irradiation spot diameter after a divergence angle correction | amendment. It is explanatory drawing of a beam shaping part and an incident beam. It is a graph which shows intensity distribution of an incident beam. It is explanatory drawing of the locus | trajectory of the short-axis component of a light ray. It is explanatory drawing of the internal reflection of the short-axis component of a light ray, and the twist around an optical axis. It is explanatory drawing of the locus | trajectory of the long-axis component of a light ray. It is explanatory drawing of the internal reflection of the major axis component of a light ray, and the twist around an optical axis. It is explanatory drawing of the internal reflection of the other component of a light ray, and the twist around an optical axis. It is explanatory drawing of the light ray which the twist around an optical axis does not produce. It is explanatory drawing of the shape of an incident beam and an emitted beam. It is a graph which shows intensity distribution of an emitted beam. It is a graph which shows intensity distribution of the outgoing beam after divergence angle correction. It is explanatory drawing of the effect by a beam shaping part. It is explanatory drawing of the beam shaping part arrange | positioned with the attitude | position different from FIG. It is explanatory drawing of the beam shaping part arrange | positioned with the attitude | position different from FIG. It is explanatory drawing of the beam shaping part arrange | positioned by offsetting the center. It is a perspective view of the beam shaping part with a square cross section. It is explanatory drawing of the incident end of the beam shaping part of FIG. It is explanatory drawing of the beam shaping part arrange | positioned with the attitude | position different from FIG. It is explanatory drawing of a comparative example. It is a perspective view of the beam shaping part whose section is a triangle. It is explanatory drawing of the incident end of the beam shaping part of FIG. It is explanatory drawing of the beam shaping part arrange | positioned with the attitude | position different from FIG. It is explanatory drawing of the beam shaping part arrange | positioned with the attitude | position different from FIG. It is a perspective view of the beam shaping part whose cross section is a perfect circle. It is explanatory drawing of the incident end of the beam shaping part of FIG. It is explanatory drawing of the comparative example of FIG. It is explanatory drawing of the beam shaping part arrange | positioned offset in the short axis direction. It is explanatory drawing of the beam shaping part arrange | positioned offset in the major axis direction. It is explanatory drawing of the beam shaping part which guides a some beam. It is a perspective view of the beam shaping part of FIG. It is explanatory drawing of the beam shaping part whose cross section is an oval. It is a perspective view of the beam shaping part whose cross section is a rectangle and whose side part is a taper shape. It is a perspective view of the beam shaping part whose cross section is a perfect circle and whose side part is a taper shape. It is a table | surface showing the evaluation result of each aspect of a beam shaping part. It is a perspective view of a mirror pipe. It is explanatory drawing of the projector apparatus using a beam shaping part. It is explanatory drawing of the beam shape of a laser diode.

“First Embodiment”
As shown in FIG. 1, an endoscope system 10 (hereinafter referred to as an endoscope system) according to a first embodiment of the present invention is obtained by imaging an endoscope 11 that images an in-vivo observation site. A processor device 12 that generates an observation image of the observation region based on the signal, a light source device 13 that supplies light irradiating the observation region to the endoscope 11, and a monitor 14 that displays the observation image are provided. The processor device 12 is provided with a console 15 that is an operation input unit such as a keyboard and a mouse.

The endoscope system 10 includes a normal observation mode for observing an observation site under white light, and a blood vessel information observation mode for observing the properties of blood vessels existing in the observation site using special light. ing. The blood vessel information observation mode is a special light observation mode for diagnosing the characteristics of blood vessels such as blood vessel pattern and oxygen saturation, and for distinguishing tumors from good to bad. As special light, the absorbance to blood hemoglobin is Narrow band light in a high wavelength range is used. The blood vessel information observation mode includes a blood vessel enhancement observation mode for displaying a blood vessel enhancement image in which blood vessels are enhanced, and an oxygen saturation observation mode for displaying an oxygen saturation image in which the oxygen saturation of blood hemoglobin is displayed.

The endoscope 11 includes an insertion portion 16 inserted into a digestive tract of a living body, an operation portion 17 provided at a proximal end portion of the insertion portion 16, and between the operation portion 17, the processor device 12, and the light source device 13. And a universal cord 18 to be connected.

The insertion portion 16 includes a distal end portion 19, a bending portion 20, and a flexible tube portion 21 that are continuously provided from the distal end. As shown in FIG. 2, on the distal end surface of the distal end portion 19, the illumination window 22 that irradiates the observation site with illumination light, the observation window 23 that receives the image light reflected by the observation site, and the observation window 23 are washed. An air supply / water supply nozzle 24 for performing air supply / water supply, a forceps outlet 25 for projecting a treatment tool such as a forceps and an electric knife, and the like are provided. An imaging element 44 (see FIG. 3) and an imaging optical system are built in the back of the observation window 23.

The bending portion 20 is composed of a plurality of connected bending pieces, and is bent in the vertical and horizontal directions by operating the angle knob 26 of the operation portion 17. By bending the bending portion 20, the direction of the distal end portion 19 is directed in a desired direction. The flexible tube portion 21 is flexible so that it can be inserted into a tortuous duct such as the esophagus or the intestine. The insertion unit 16 includes a communication cable that communicates a drive signal for driving the image sensor 44 and an image signal output from the image sensor 44, and a light guide 43 that guides illumination light supplied from the light source device 13 to the illumination window 22. (See FIG. 3) is inserted.

In addition to the amble knob 26, the operation unit 17 includes a forceps port 27 for inserting a treatment instrument, an air / water supply button for performing air / water supply operation, a release button for taking a still image, and the like. .

A communication cable and a light guide 43 extending from the insertion portion 16 are inserted into the universal cord 18. One end of the universal cord 18 is fixed to the endoscope 11, and a connector 28 is provided at the other end serving as an open end. The connector 28 is a composite type connector composed of a communication connector 28a and a light source connector 28b. One end of a communication cable is disposed in the communication connector 28a, and the communication connector 28a is detachably connected to the processor device 12. The light guide connector 28 b is provided with an incident end of the light guide 43, and the light source connector 28 b is detachably connected to the light source device 13.

As shown in FIG. 3, the light source device 13 includes three types of first to third light source modules 31 to 33 each having a different emission wavelength, and a light source control unit 34 that drives and controls them. The light source control unit 34 controls drive timing and synchronization timing of each unit of the light source device 13.

The first to third light source modules 31 to 33 have laser diodes LD1 to LD3 that respectively emit narrowband light in a specific wavelength range. The laser diodes LD1 to LD3 are light emitting elements composed of semiconductors. As shown in FIG. 4, in the blue (B color) region, the laser diode LD1 emits narrowband light N1 having a wavelength region limited to 440 ± 10 nm and a center wavelength of 445 nm, for example. In the blue (B color) region, the laser diode LD2 emits narrowband light N2, which is a narrowband light having a wavelength range limited to 410 ± 10 nm and a center wavelength of 405 nm, for example. In the blue (B color) region, the laser diode LD3 emits narrowband light N3, which is a narrowband light whose wavelength range is limited to 470 ± 10 nm and whose center wavelength is 473 nm, for example. As the laser diodes LD1, LD2, and LD3, InGaN-based, InGaNAs-based, and GaNAs-based ones can be used. The laser diodes LD1 to LD3 are preferably broad area type laser diodes having a wide stripe width (waveguide width) capable of increasing the output.

The first light source module 31 is a light source unit that emits white light for normal observation. The first light source module 31 includes a phosphor 36 in addition to the laser diode LD1. As shown in FIG. 4, the phosphor 36 is excited by the 445 nm blue-band narrow-band light N1 emitted from the laser diode LD1, and emits fluorescence FL in a wavelength region extending from the green region to the red region. The phosphor 36 absorbs a part of the narrowband light N1 to emit fluorescence FL and transmits the remaining narrowband light N1. The narrowband light N1 that passes through the phosphor 36 is diffused by the phosphor 36. White light is generated by mixing the transmitted narrow-band light N1 and the excited fluorescence FL. As the phosphor 36, for example, a YAG-based or BAM (BgMgAl ₁₀ O ₁₇ ) -based phosphor is used. Two first light source modules 31 are provided so that the amount of white light increases.

The second light source module 32 is a light source unit for blood vessel enhancement observation. In FIG. 5 showing the absorption spectrum of blood hemoglobin, the absorption coefficient μa of blood hemoglobin has a wavelength dependence, increases rapidly in the region where the wavelength is 450 nm or less, and has a peak in the vicinity of 405 nm. Yes. Further, although the wavelength is lower than that of 450 nm or less, there is also a peak at wavelengths of 530 nm to 560 nm. When the observation site is irradiated with light having a wavelength with a large extinction coefficient μa, the blood vessel has a large absorption, and an image having a large contrast between the blood vessel and its peripheral portion is obtained.

Further, as shown in FIG. 6, the light scattering characteristic of the living tissue is also wavelength-dependent, and the scattering coefficient μS increases as the wavelength becomes shorter. Scattering affects the depth of light penetration into living tissue. That is, the greater the scattering, the more light that is reflected near the mucosal surface layer of the biological tissue and the less light that reaches the mid-deep layer. Therefore, the shorter the wavelength, the lower the depth of penetration, and the longer the wavelength, the higher the depth of penetration. In view of such light absorption characteristics of hemoglobin and light scattering characteristics of living tissue, the wavelength of light for blood vessel enhancement is selected.

The 405-nm narrow-band light N2 emitted from the second light source module 32 has a low depth of penetration and is therefore absorbed by the surface blood vessels, and is therefore used as light for emphasizing the surface blood vessels. By using the narrowband light N2, the superficial blood vessel can be depicted with high contrast in the observation image. Further, the green component of white light emitted from the first light source module 31 is used as the light for emphasizing the middle deep blood vessel. In the absorption spectrum shown in FIG. 5, the light absorption coefficient gradually changes in the green region of 530 nm to 560 nm as compared with the blue region of 450 nm or less. It is not required to be. Therefore, as described later, a green component color-separated from white light by the G-color micro color filter of the image sensor 44 is used.

The third light source module 33 is a light source unit for observing oxygen saturation. In FIG. 5, an absorption spectrum Hb indicates an absorption spectrum of reduced hemoglobin not bonded to oxygen, and an absorption spectrum HbO2 indicates an absorption spectrum of oxidized hemoglobin bonded to oxygen. Thus, reduced hemoglobin and oxyhemoglobin have different light absorption characteristics, and a difference occurs in the light absorption coefficient μa except for the isosbestic point (intersection of each spectrum Hb and HbO 2) showing the same light absorption coefficient μa. If there is a difference in the extinction coefficient μa, even if the light having the same light intensity and the same wavelength is irradiated, the reflectance changes if the oxygen saturation changes. In the oxygen saturation observation mode, the oxygen saturation is measured using narrowband light N3 having a wavelength of 473 nm emitted from the third light source module 33 as a wavelength having a difference in the absorption coefficient μa.

The light source controller 34 turns on and off the laser diodes LD1 to LD3 and controls the amount of light via the driver 37. Specifically, the light source controller 34 turns on the laser diodes LD1 to LD3 by applying a drive pulse. Then, by performing PWM (Pulse Width Modulation) control for controlling the duty ratio of the drive pulse, the light emission amount is controlled by changing the drive current value. The control of the drive current value may be PAM (Pulse Amplitude Modulation) control that changes the amplitude of the drive pulse.

A branched light guide 41 is provided on the downstream side of the optical path of the first to third light source modules 31 to 33. The branching light guide 41 is an optical path integrating unit that integrates the optical paths of the first to third light source modules 31 to 33 into one optical path, as will be described in detail later. Since the light guide 43 of the endoscope 11 has one incident end, each branch light guide 41 supplies light from the first to third light source modules 31 to 33 to the endoscope 11 at each stage. The light paths of the modules 31 to 33 are integrated. The branched light guide 41 has branch portions 41a to 41d whose entrance ends are branched into a plurality of portions, and emits light incident from the respective branch portions 41a to 41d from one exit end 41e.

The two first light source modules 31 are respectively arranged so as to face the incident surfaces of the branch portions 41a and 41b of the branch light guide 41, and the second and third light source modules 32 and 33 are respectively branched portions 41c and 41d. It arrange | positions so that it may oppose with the entrance plane.

The exit end 41e of the branched light guide 41 is disposed near the receptacle connector 42 to which the connector 28b of the endoscope 11 is connected. A homogenizer 50, which will be described later, is provided at the emission end 41e, and the light of the first to third light source modules 31 to 33 incident on the branched light guide 41 is distributed to the connector 28b via the homogenizer 50. The light guide 43 of the endoscope 11 is supplied.

The endoscope 11 includes a light guide 43, an imaging device 44, an analog processing circuit 45 (AFE: Analog Front End), and an imaging control unit 46. The light guide 43 is a fiber bundle obtained by bundling a plurality of optical fibers (see reference numeral 201 in FIG. 18), and when the connector 28 is connected to the light source device 13, the incident end of the light guide 43 is the light source device 13. It faces the emission end of the homogenizer 50. The exit end of the light guide 43 branches into two at the front stage of the illumination window 22 so that light is guided to the two illumination windows 22.

In the back of the illumination window 22, an irradiation lens 48 is disposed. The light supplied from the light source device 13 is guided to the irradiation lens 48 by the light guide 43 and irradiated from the illumination window 22 toward the observation site. The irradiation lens 48 is a concave lens, and widens the divergence angle of the light emitted from the light guide 43. Thereby, illumination light can be irradiated to the wide range of an observation site | part.

In the back of the observation window 23, an objective optical system 51 and an image sensor 44 are arranged. The image light reflected by the observation site enters the objective optical system 51 through the observation window 23 and is imaged on the imaging surface 44 a of the imaging element 44 by the objective optical system 51.

The imaging device 44 is composed of a CCD image sensor, a CMOS image sensor, or the like, and has an imaging surface 44a in which a plurality of photoelectric conversion elements constituting pixels such as photodiodes are arranged in a matrix. The image sensor 44 photoelectrically converts the light received by the imaging surface 44a and accumulates signal charges corresponding to the amount of received light in each pixel. The signal charge is converted into a voltage signal by an amplifier and read out. The voltage signal is output from the image sensor 44 as an image signal, and the image signal is sent to the AFE 45.

The image sensor 44 is a color image sensor, and micro-color filters of three colors B, G, and R having spectral characteristics as shown in FIG. 7 are assigned to each pixel on the imaging surface 44a. The white light emitted from the first light source module 31 is split into three colors B, G, and R by the micro color filter. The arrangement of the micro color filter is, for example, a Bayer arrangement.

As shown in FIG. 8A, in the normal observation mode, the image sensor 44 performs an accumulation operation for accumulating signal charges and a read operation for reading the accumulated signal charges within an acquisition period of one frame. In the normal observation mode, the laser diode LD1 is turned on in accordance with the accumulation timing, white light composed of the narrowband light N1 and fluorescence FL is irradiated as illumination light to the observation site, and the reflected light is incident on the image sensor 44. . In the image sensor 44, the white light is color-separated by a micro color filter, the B pixel receives reflected light corresponding to the narrowband light N1, the G pixel in the fluorescent FL, the G pixel in the fluorescent FL, The R pixel receives reflected light corresponding to the R component. The image sensor 44 sequentially outputs the image signals B, G, and R for one frame in which the pixel values of the B, G, and R pixels are mixed according to the frame rate in accordance with the readout timing. Such an imaging operation is repeated while the normal observation mode is set.

As shown in FIG. 8B, in the blood vessel enhancement observation mode, the second light source module 32 is turned on in addition to the first light source module 31 in accordance with the accumulation timing. When the first light source module 31 is turned on, similarly to the normal observation mode, the observation site is irradiated with white light (N1 + FL) composed of the narrowband light N1 and the fluorescence FL as illumination light. When the second light source module 32 is turned on, the narrowband light N2 is added to the white light (N1 + FL), and these are irradiated to the observation site as illumination light.

The illumination light obtained by adding the narrow-band light N2 to the white light is split by the B, G, and R micro color filters of the image sensor 44 as in the normal observation mode. In the image sensor 44, the B pixel receives the narrowband light N2 in addition to the narrowband light N1. The G pixel receives the G component of the fluorescence FL. The R pixel receives the R component of the fluorescence FL. Even in the blood vessel enhancement observation mode, the image sensor 44 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the readout timing. Such an imaging operation is repeated while the blood vessel enhancement observation mode is set.

As shown in FIG. 8C, in the oxygen saturation observation mode, the first light source module 31 is turned on in accordance with the accumulation timing. When the first light source module 31 is lit, white light (N1 + FL) is irradiated to the observation site as in the normal observation mode. In the next frame, the first light source module 31 is turned off, and the third light source module 33 is turned on instead, and the narrow-band light N3 is irradiated onto the observation site. Even in the oxygen saturation observation mode, the image sensor 44 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the readout timing.

However, in the oxygen saturation observation mode, unlike the normal observation mode and the blood vessel enhancement observation mode, white light (N1 + FL) and narrowband light N3 are alternately irradiated, so that the image signal B corresponding to white light in the first frame is used. , G, R are output, and in the next frame, the image signals B, G, R corresponding to the narrowband light N3 are output, and the image signals B, G, R are carried corresponding to each illumination light. The information to be changed also changes every other frame. Such an imaging operation is repeated while the oxygen saturation mode is set.

3, the AFE 45 includes a correlated double sampling circuit (CDS), an automatic gain control circuit (AGC), and an analog / digital converter (A / D) (all not shown). The CDS performs a correlated double sampling process on the analog image signal from the image sensor 44, and removes noise caused by resetting the signal charge. AGC amplifies an image signal from which noise has been removed by CDS. The A / D converts the image signal amplified by AGC into a digital image signal having a gradation value corresponding to a predetermined number of bits and inputs the digital image signal to the processor device 12.

The imaging control unit 46 is connected to the controller 56 in the processor device 12 and inputs a drive signal to the imaging device 44 in synchronization with the base clock signal input from the controller 56. The imaging element 44 outputs an image signal to the AFE 45 at a predetermined frame rate based on the drive signal from the imaging control unit 46.

The processor device 12 includes a DSP (Digital Signal Processor) 57, an image processing unit 58, a frame memory 59, and a display control circuit 60 in addition to the controller 56. The controller 56 includes a CPU, a ROM for storing control programs and setting data necessary for control, a RAM (Random Access Memory) that loads a program and functions as a working memory, and the CPU executes the control program. Each part of the processor unit 12 is controlled.

The DSP 57 acquires an image signal output from the image sensor 44. The DSP 57 separates an image signal in which signals corresponding to B, G, and R pixels are mixed into B, G, and R image signals, and performs pixel interpolation processing on the image signals of the respective colors. In addition, the DSP 57 performs signal processing such as gamma correction and white balance correction on each of the B, G, and R image signals.

The frame memory 59 stores image data output from the DSP 57 and processed data processed by the image processing unit 58. The display control circuit 60 reads the image processed image data from the frame memory 59, converts it into a video signal such as a composite signal or a component signal, and outputs it to the monitor 14.

As shown in FIG. 9A, in the normal observation mode, the image processing unit 58 displays the display image for normal observation based on the image signals B, G, and R separated into B, G, and R colors by the DSP 57. Is generated. The display image is output to the monitor 14 as an observation image. The image processing unit 58 updates the display image every time the image signals B, G, and R in the frame memory 59 are updated.

As shown in FIG. 9B, in the blood vessel enhancement observation mode, the image processing unit 58 generates a display image for blood vessel enhancement observation based on the image signals B, G, and R. The image signal B in the blood vessel enhancement observation mode includes information on the narrow band light N2 in addition to the B component of white light (including a part of the narrow band light N1 and the fluorescence FL). It is drawn with high contrast. In lesions such as cancer, there is a tendency to increase the density of superficial blood vessels compared to normal tissues, so there is a feature in the blood vessel pattern, so in blood vessel enhancement observation for the purpose of tumor discrimination, It is preferable that the superficial blood vessel is clearly depicted.

Further, when emphasizing the superficial blood vessel, for example, the superficial blood vessel region is extracted based on the image signal B, and the extracted region is subjected to contour emphasis processing or the like. Then, the image signal B that has undergone the contour enhancement processing is combined with a full-color image generated from the image signals B, G, and R. By doing so, the superficial blood vessels are more emphasized. The same processing may be performed on the middle- and deep-layer blood vessels in addition to the surface blood vessels. When emphasizing the middle-and-deep blood vessel, the region of the middle-and-deep blood vessel is extracted from the image signal G that includes a lot of information about the middle-and-deep blood vessel, and contour enhancement processing is performed on the extracted region. The completed image signal G is combined with a full-color image generated from the image signals B, G, and R.

The display image for blood vessel enhancement observation is generated based on the three color image signals B, G, and R in the same way as for normal observation, so that the observation site can be displayed in full color. The image signal B in the mode has a higher blue density than the image signal B in the normal observation mode. For this reason, when a display image for blood vessel enhancement observation is generated, color correction may be performed so as to obtain a color similar to that of the normal observation display image. The image processing unit 58 generates a display image for blood vessel enhancement observation every time the image signals B, G, and R in the frame memory 59 are updated.

As a method for generating a display image for blood vessel enhancement observation, the image signal B is generated using only two colors of the image signals B and G without using the image signal R, and the image signal B is generated by the B channel and the G channel of the monitor 14. In addition, a method of displaying the observation region in a pseudo color, such as a method of assigning a signal corresponding to the image signal G to the R channel of the monitor 14, may be employed.

As shown in FIG. 9C, in the oxygen saturation observation mode, the image processing unit 58 uses the image signals G1 and R1 acquired under white light and the image signal acquired under narrowband light N3. Based on B2, oxygen saturation calculation processing is performed. The pixel value of the image signal B2 includes blood volume (concentration) information in addition to oxygen saturation. In order to obtain the oxygen saturation more accurately, it is necessary to separate blood volume information from the pixel value of the image signal B2. The image processing unit 58 performs an inter-image calculation with the image signal B using the image signal R showing a high correlation with the blood volume, and separates oxygen saturation and blood volume information.

Specifically, the image processing unit 58 collates pixel values at the same position of the image signals B2, G1, and R1, and calculates a signal ratio B / G between the pixel value of the image signal B2 and the pixel value of the image signal G1. The signal ratio R / G between the pixel value of the image signal R1 and the pixel value of the image signal G1 is obtained. The image signal G1 is used as a reference signal representing the brightness level of the observation region in order to normalize the pixel values of the image signal B2 and the image signal R1. Then, based on a table that stores the correlation between the signal ratios B / G and R / G, the oxygen saturation, and the blood volume, the oxygen saturation that is obtained by separating the blood volume information is calculated. . Then, the full color image generated based on the image signals B1, G1, and R1 is subjected to color conversion in accordance with the calculated oxygen saturation value to generate a display image for oxygen saturation observation.

In FIG. 10, the branched light guide 41 provided in the light source device 13 is a fiber bundle in which a plurality of optical fibers are bundled in the same manner as the light guide 43 of the endoscope 11. The branched light guide 41 has all the optical fibers bundled together at the exit end 41e, and divides all the optical fibers into four on the way to the incident end, A plurality of branch portions 41a to 41d are formed by bundling.

The thicknesses of the branch portions 41a and 41b and the branch portions 41c and 41d are changed by changing the number of bundled optical fibers, and the diameters thereof are D1 and D2. The diameter D1 of the branch portions 41a and 41b is thicker than the diameter D2 of the branch portions 41c and 41d. One reason for the difference in thickness is that the first light source module 31 that faces the branch portions 41a and 41b uses the phosphor 36, and therefore the second light source module 32 that does not use the phosphor 36. This is because the diameter of the emitted beam is larger than that of. Another reason is that the first light source module 31 emits white light for normal observation, so that a larger amount of light than the second light source modules 32 and 33 for special light observation is secured.

Specifically, the diameter of the light guide 43 of the endoscope 11 is about 2 mm, and the diameter of the exit end 41 e of the branched light guide 41 is about 2 mm accordingly. The diameter D1 of the branch portions 41a and 41b is about 1.0 to 1.4 mm, and the diameter D2 of the branch portions 41c and 41d is about 0.5 to 0.8 mm.

A homogenizer 50 is provided at the exit end 41e of the branched light guide 41. The homogenizer 50 equalizes the light quantity distribution of the light of each color emitted from the first to third light source modules 31 to 33 and emitted from the emission end 41e in the front stage of the light guide 43 of the endoscope 11. The homogenizer 50 is formed of a transparent material such as transparent glass and is a columnar body having a circular cross section perpendicular to the optical axis, and totally reflects light incident from the incident end 50a on the inner side surface 50b serving as an interface with air. Then, it propagates in the optical axis direction and exits from the exit end 50c.

As shown in FIG. 11, in the branched light guide 41, for example, an optical fiber having one end located in each of the regions a to d partitioned by a two-dot chain line at the emission end 41e is allocated to each of the branch portions 41a to 41d. Each of the optical fibers corresponding to the branch portions 41a to 41d is unevenly distributed at the exit end 41e. The light incident from the branch portions 41a to 41d is propagated in each optical fiber, and naturally there is no propagation between the optical fibers. Therefore, at the emission end 41e, white light emitted from the first light source module 31 is emitted from the upper left and upper right areas a and b, and the narrowband light N2 emitted from the second light source module 32 is emitted from the area c, and the area d Thus, the light of each color is unevenly distributed such that the narrow band light N3 emitted from the third light source module 33 is emitted. Therefore, the light quantity distribution of each color becomes non-uniform in the cross section of the beam emitted from the emission end 41e.

As shown in FIG. 12, the homogenizer 50 propagates light in the direction of the optical axis while totally reflecting light incident from the end surface of the incident end 50a on the side surface 50b. Therefore, the incident position of light in the cross section orthogonal to the optical axis. And the emission position changes. By such an action, the uneven distribution of the light of each color at the emission end 41e of the branched light guide 41 is eliminated, and the light quantity distribution of the light of each color is made uniform in the cross section of the incident beam incident on the light guide 43. The homogenizer 50 and the emission end 41e are integrated by heat-sealing with the end faces abutting each other.

As shown in FIGS. 13 and 14, the first light source module 31 includes a laser module 61, a fluorescent part 62, a single-line optical fiber 63 that guides the light of the laser module 61 to the fluorescent part 62, and a fluorescent part 62. The divergence angle correction | amendment part 64 attached to the front-end | tip of this is provided. The laser module 61 includes a light emitting element portion 66 having a laser diode LD1 and a case 67 that accommodates the light emitting element portion 66. The case 67 is provided with a connection portion 67a that connects one end of the optical fiber 63. This is a so-called receptacle type module in which a condensing lens 68 is built in a case 67.

The light emitting element portion 66 is obtained by mounting a laser diode LD1 as a light emitting element on one surface of a disk-shaped stem 66a serving as a support, and covering the laser diode LD1 with a resin-made cylindrical transparent cap 66b. . A lead wire 66c extends from the back surface of the stem 66a.

As shown in FIG. 54, the laser diode LD1 is formed by joining a P layer made of a P-type semiconductor and an N layer made of an N-type semiconductor with an active layer interposed therebetween, and emits laser light from the active layer by laser oscillation. . Laser light is highly divergent, but is divergent light whose beam shape spreads from the light emitting point in a substantially conical shape. The cross-sectional shape orthogonal to the optical axis of the beam is substantially elliptical. The laser light is condensed at the incident end of the optical fiber 63 by the condenser lens 68.

The outgoing end of the optical fiber 63 is connected to the fluorescent part 62. The fluorescent part 62 is obtained by filling a fluorescent material 36 in a cylindrical protective case 62a having a light shielding property. An insertion hole into which the optical fiber 63 is inserted is formed at the center of the phosphor 36. The optical fiber 63 is inserted into the phosphor 36 with a connection ferrule (not shown) attached to its end.

The phosphor 36 is obtained by dispersing and solidifying a powdery fluorescent material in a binder made of a resin material. Since the fluorescent material is dispersed, the emission point of the excited fluorescence FL is the entire emission end face of the phosphor 36. Further, since the laser light transmitted through the phosphor 36 is also diffused in the phosphor 36 by the light diffusing action of the binder, the entire area of the emission end face becomes a light emitting point.

Like the laser diode LD1, the light emitted from the phosphor 36 is a diverging light that spreads in a substantially conical shape from the light emitting point. However, compared with the laser diode LD1, the area of the light emitting point and the beam divergence angle are large.

A divergence angle correction unit 64 that corrects the divergence angle of light emitted from the emission end surface 36a of the phosphor 36 is provided in front of the fluorescent unit 62. The divergence angle correction unit 64 has a cylindrical shape whose diameter increases toward the tip, and is formed of a light shielding material. The divergence angle correction unit 64 reduces the divergence angle by regulating the spread of the divergent light emitted from the phosphor 36. The divergence angle correction unit 64 has a mirror surface formed by coating the inner wall surface 64a with a reflective material, and the inner wall surface 64a functions as a reflector. Therefore, the light propagates in the optical axis direction while being specularly reflected by the inner wall surface 64a. Since the light absorption is reduced by making the inner wall surface 64a a mirror surface, there is little light transmission loss.

The divergence angle correction unit 64 is set with an inclination angle with respect to the diameter and the optical axis in consideration of the diameter D1 of the branch portions 41a and 41b. The diameter and the tilt angle are changed from the first light source module 31 to the branch portions 41a and 41b. Is set so that the spot diameter of the beam incident on the beam substantially coincides with the diameter D1 of the branch portions 41a and 41b.

Also, the divergence angle is set according to the NA (numerical aperture: Numerical Aperture) of an optical fiber that is a strand of a fiber bundle such as the branched light guide 41 or the light guide 43 of the endoscope 11. As is well known, an optical fiber is composed of a core having a high refractive index and a clad having a low refractive index disposed around the core. The incident light incident from the incident end of the optical fiber is a boundary between the core and the clad. And propagates in the optical axis direction while totally reflecting. In order to propagate the light, it is necessary to make the light incident on the incident end of the optical fiber at an incident angle that satisfies the total reflection condition.

NA is an index representing how much light can be collected by the optical fiber, and is defined by sin of the maximum light receiving angle θmax (NA = sin θmax). The larger the maximum light receiving angle θmax, the larger the NA value. If the incident angle of the incident light incident on the optical fiber is less than or equal to the maximum light receiving angle θmax, total reflection occurs at the boundary between the core and the clad in the optical fiber, so that the incident light propagates in the optical axis direction and is guided. . When the incident angle exceeds the maximum light receiving angle θmax, light is not guided because it is transmitted without being totally reflected. Incident light that is not guided becomes a light transmission loss. In order to reduce the light transmission loss, the divergence angle correction unit 64 regulates the divergence angle of the beam of the first light source module 31 to be equal to or less than the maximum light receiving angle θmax.

Further, as described above, in the laser beam emitted from the laser diode LD1, the cross-sectional shape orthogonal to the optical axis is substantially elliptical. However, since the light beam contained in the laser light is diffused in the phosphor 36, it is emitted in almost all directions from almost the entire emission end face of the phosphor 36. Since the cross-sectional shape of the divergence angle correction unit 64 is substantially true circle, the cross-sectional shape of the beam BM (see FIG. 54) of the laser light emitted from the phosphor 36 is made substantially circular by the divergence angle correction unit 64. It is shaped. Similarly, the fluorescence excited by the laser light is shaped into a substantially perfect circle by the action of the divergence angle correction unit 64. Therefore, the first light source module 31 emits mixed light in which laser light (narrow band light N1) and fluorescence (FL) are mixed, and the mixed light is emitted as a beam having a substantially circular cross section. Is done.

As shown in FIG. 15, the second light source module 32 includes a light emitting element unit 71, a divergence angle correction unit 72, and a beam shaping unit 73. The light emitting element unit 71 includes a laser diode LD2, and the form thereof is the same as that of the light emitting element unit 66 of the first light source module 31. The divergence angle correction unit 72 and the beam shaping unit 73 are both light guide rods that are columnar bodies made of a transparent material such as quartz, and are also called light pipes, light tunnels, and the like.

The light emitting element unit 71 is disposed to face the end surface (incident surface) of the incident end 73 a of the beam shaping unit 73, the end surface (exit surface) of the emission end 73 c of the beam shaping unit 73, and the incident angle of the divergence angle correcting unit 72. The end surfaces of the ends 72a are arranged to face each other. In the divergence angle correction unit 72, for example, the end surface of the incident end 72 a and the end surface of the output end 73 c of the beam shaping unit 73 are thermally fused, and the end surface of the incident end 73 a of the beam shaping unit 73 is the tip of the light emitting element unit 71. It is heat-sealed with the end face. Thereby, the three components of the divergence angle correction part 72, the beam shaping part 73, and the light emitting element part 71 are integrated. Since they are integrated by heat fusion, there is less interface with air in the optical path as compared to the case where each part is not integrated and air is interposed between each part. Therefore, there is little Fresnel loss due to the boundary surface, and light transmission loss can be reduced.

As shown in FIG. 16, the divergence angle correction unit 72 and the beam shaping unit 73 are similar to the homogenizer 50, and light incident from the incident surface is formed on the inner surface (reflection side surface) of the side surface serving as a boundary surface with air. It is an optical element that propagates in the direction of the optical axis while being totally reflected and exits from the exit surface.

The divergence angle correction unit 72 has a tapered shape in which the diameter of the emission end 72c is smaller than that of the incident end 72a, and the side surface 72b has a tapered shape inclined with respect to the optical axis. Therefore, when the reflected light is repeatedly reflected on the side surface 72b so that the incident light has a second reflection angle θ2 smaller than the first reflection angle θ1, the reflection angle θ gradually decreases. A decrease in the reflection angle θ means that the divergence angle increases. Due to the action of the divergence angle correction unit 72, when the divergence angle of the light emitted from the laser diode LD2 is β1, the divergence angle at the emission end 72c of the divergence angle correction unit 72 is expanded to β2.

The longer the length of the divergence angle correction unit 72 in the optical axis direction, the greater the number of reflections on the side surface 72b, so the effect of expanding the divergence angle is greater. Moreover, the larger the inclination angle of the side surface 72b, the greater the effect of expanding the divergence angle by one reflection.

The correction amount of the divergence angle correction unit 72 is set so that the divergence angle β2 substantially coincides with the divergence angle α (see FIG. 14) emitted from the first light source module 31. The divergence angle is also preserved in the light guiding process by the homogenizer 50 or the light guide 43 of the endoscope 11. Therefore, as shown in FIG. 17, the light divergence angle α of the first light source module 31 and the light divergence angle β ( By matching β2) in FIG. 16, the light irradiation spot diameter SDα of the first light source module 31 and the light irradiation spot diameter SDβ of the second light source module 32 in the observation region SB can be made the same. If the irradiation spot diameters SDα and SDβ do not match, unevenness occurs in the way they overlap, causing color unevenness. By causing the divergence angle correction unit 72 to match the divergence angle β with the divergence angle α, the irradiation spot diameters SDα and SDβ can be made to match, so that the color unevenness is prevented.

In FIG. 15, a beam shaping unit 73 is a columnar body having a longitudinal axis extending in the longitudinal direction from the end face (incident surface) of the incident end 73a toward the end face (exiting surface) of the exit end 73c and parallel to the optical axis. The cross-sectional shape orthogonal to the longitudinal axis is a hexagonal prism having a hexagonal shape. Since the side surface portion 73b is formed along the longitudinal direction and the cross-sectional shape is a hexagonal column, the side surface portion 73b is naturally composed of six planes.

As shown in FIG. 16, the beam emitted from the laser diode LD2 enters the incident end 73a of the beam shaping unit 73. The inner surface of the side surface portion 73b becomes a boundary surface with air. Therefore, the inner surface of the side surface portion 73b becomes a reflective side surface in which the light incident on the inner surface of the side surface portion 73b at an angle satisfying the total reflection condition among the beams incident in the beam shaping portion 73 is totally reflected. The beam shaping unit 73 guides the beam incident on the incident end 73a in the optical axis direction while totally reflecting the inner surface of the side surface portion 73b.

The beam emitted from the laser diode LD2 has a substantially elliptical cross-sectional shape orthogonal to the optical axis as in the laser diode LD1 (see FIG. 54). The beam shaping unit 73 shapes the substantially elliptical cross-sectional shape of the beam into a substantially perfect circle during light guide, and emits the shaped beam from the emission end 73c.

As shown in FIG. 18, the beam shaping unit 73 is connected to the light emitting element unit 71 so that the optical axis A passing through the center of the hexagon and the light emission center OP of the incident beam BMin incident from the laser diode LD2 substantially coincide with each other. The relative position is positioned. For example, the incident beam BMin is incident on the beam shaping unit 73 in a vertically long state in which the long axis LA is positioned in the vertical direction (Y direction) and the short axis SA is positioned in the horizontal direction (X direction). Light rays included in the incident beam BMin spread radially from the emission center OP.

As shown in FIG. 19, the intensity distribution of the incident beam BMin having a substantially elliptical cross section has anisotropy, and the major axis LA direction indicated by the solid line and the minor axis SA direction indicated by the dotted line. The intensity distribution is different.

Here, the graph of the intensity distribution is a graph in which the vertical axis represents the radiation intensity and the horizontal axis represents the angle (radiation angle) of the measurement position at which the radiation intensity is measured. The intensity distribution is a distribution in which the radiation intensity at each radiation angle is measured while rotating the measurement unit around the laser diode, and the measured radiation intensity is plotted. In the measurement method, a position where the optical axis (emission center) of the measurement unit and the laser diode coincide is set as a measurement position with a radiation angle of 0 °, and the measurement unit is rotated in the positive direction and the negative direction based on the position. The radiation intensity at the measurement position (radiation angle) is measured. The radiation intensity becomes maximum at the measurement position where the radiation angle is 0 °, and the intensity distribution is a mountain-shaped distribution that decreases toward the periphery (as the radiation angle increases). The divergence angle θ of the laser diode is expressed in half-width (half width at half maximum, HWHM), which is 1/2 of the full width when the half value is shown with respect to the peak value (max) of the radiation intensity in the graph. Is done. The divergence angle θyin in the major axis LA direction is wide, and the divergence angle θxin in the minor axis SA direction is narrowed. Specifically, the divergence angle θyin in the major axis LA direction is about 11 ° to 14 °, and the divergence angle θxin in the minor axis SA direction is about 5 ° to 7 °, which is half of the divergence angle.

Further, in FIG. 18, the beam shaping unit 73 is arranged in a posture inclined by an angle φL around the optical axis A with respect to the long axis LA and the short axis SA. In the hexagonal cross section of the beam shaping unit 73, the angle φL connects two opposing vertices, an axis passing through the optical axis A is A1, a midpoint between two opposing sides S orthogonal to the axis A1 The axis A1 and the axis A2 are angles formed between the major axis LA and the minor axis SA, where A2 is an axis passing through the optical axis A. The angle φL is 15 ° in this example.

When the beam shaping unit 73 is tilted in this way, both the long axis LA and the short axis SA of the incident beam BMin are not orthogonal to the hexagonal sides S constituting the inner surface of the side surface portion 73b of the beam shaping unit 73. It becomes. In other words, the long axis LA and the short axis SA and the inner surface (reflection side surface) of the side surface portion 73b cross each other at an angle other than vertical. As a result, of the light rays included in the incident beam BMin, both the long axis component and the short axis component parallel to the major axis LA and the minor axis SA are incident on each side S at an angle other than perpendicular. become. In this way, the trajectory of the light ray when incident on each side S at an angle other than perpendicular is as follows.

20 and 21, assuming that the short axis component of the light beam of the incident beam BMin is RS, the short axis component RS is incident on the incident end 73a of the beam shaping unit 73 from the light emission center OP. Since the emission center OP and the optical axis A coincide with each other, the short axis component RS has a short axis SA with the optical axis A as a base point in a cross section orthogonal to the optical axis A (Z direction) through which the beam shaping unit 73 passes. Is emitted in the X direction parallel to the. And it injects into the one side S of the hexagon which comprises the inner surface of the side part 73b. This is the first reflection point P1, and the short axis component RS is totally reflected. Here, due to the inclination of the beam shaping unit 73 by the angle φL, the minor axis component RS has an angle other than perpendicular to the side S, that is, an incident angle of the angle φL with respect to the normal H of the side S. Therefore, the light is reflected at the reflection point P1 at the reflection angle φL. This means that a twist occurs around the optical axis A with respect to the short-axis component RS due to reflection at the reflection point P1.

The short axis component RS reflected at the reflection point P1 is incident on another side S, and this is the second reflection point P2. Due to the reflection at the reflection point P1, the short axis component RS is twisted around the optical axis A, so that the reflection point P2 also enters the side S at an angle other than perpendicular. And it reflects with the reflection angle of 0 degree or more with respect to the normal line of the edge | side S, and goes to the reflection point P3. Similarly, the short-axis component RS is incident on the reflection point P3 at an angle other than perpendicular to the side S, and twisting around the optical axis A occurs at the reflection point P3.

The short axis component RS repeats torsion around the optical axis A at each of the reflection points P1 to P3. Therefore, the short axis component RS travels in the direction of the optical axis A as if turning around the optical axis A in the beam shaping unit 73, as indicated by a two-dot chain arc-shaped arrow shown in FIG. Become. Thus, since the radiation direction of the short axis component RS changes during the light guide in the beam shaping unit 73, the minor axis component RS is emitted in a direction different from the radiation direction at the time of incidence. For example, if the torsion angle around the optical axis A due to three reflections at the reflection points P1 to P3 during light guide is 90 °, the radiation direction of the short axis component RS parallel to the X direction at the time of incidence is Is a component orthogonal to the Y direction.

On the other hand, as shown in FIG. 20, in the short axis component RS, in the plane parallel to the optical axis A, the divergence angle θx at the time of incidence is preserved even during light guiding, and the divergence angle θx is maintained. It is emitted at. This is because, unlike the divergence angle correction unit 72 (see FIG. 16), the beam shaping unit 73 has a constant thickness from the entrance end 73a to the exit end 73c, and the side surface portion 73b is parallel to the optical axis. is there.

22 and 23 show the trajectory of the long-axis component RL orthogonal to the short-axis component RS. The long axis component RL is radiated in the Y direction with the optical axis A as a base point in a cross section orthogonal to the optical axis A. The major axis component RL is an angle other than perpendicular to the side S, that is, the angle of the side S due to the inclination of the beam shaping unit 73 at the angle φL at the first reflection point P1 after entering the beam shaping unit 73. Incident with an incident angle of φL with respect to the normal H. Therefore, the long axis component RL is twisted around the optical axis A due to reflection at the reflection point P1, as with the short axis component RS.

As a result, the long axis component RL repeats torsion around the optical axis A every time it is reflected at the reflection points P2 and P3. As shown in the arc of the two-dot chain line shown in FIG. It advances while turning around the optical axis A. For this reason, the long-axis component RL also emits in a direction different from the radiation direction at the time of incidence, since the radiation direction of the long-axis component RL changes during light guide in the beam shaping unit 73, as with the short-axis component RS. For example, if the torsion angle around the optical axis A due to three reflections at the reflection points P1 to P3 during light guiding is 90 °, the long-axis component RL whose radiation direction at the time of incidence is parallel to the Y direction is Is a component parallel to the X direction.

On the other hand, as shown in FIG. 22, for the long axis component RL, the divergence angle θy at the time of incidence is preserved even during light guiding in the plane parallel to the optical axis, as in the short axis component RS. The light is emitted with the divergence angle θy maintained.

In the above description, the short axis component RS and the long axis component RL of the light rays included in the incident beam BMin have been described. However, the same applies to many of the intermediate components between the short axis component RS and the long axis component RL. Twist around the optical axis A occurs.

For example, the light ray R1 shown in FIG. 24 is an intermediate component in which the radiation direction of the incident beam BMin is between the short-axis component RS and the long-axis component RL. Like the short axis component RS and the long axis component RL, the light ray R1 is incident at an angle other than perpendicular to the side S. Therefore, the reflection at the reflection points P1 to P3 causes twisting around the optical axis A to be emitted. The direction changes. However, since the radiation direction of the light ray R1 is different from the short axis component RS and the long axis component RL, the incident angle with respect to the side S at the first reflection point P1 is different from the short axis component RS and the long axis component RL. Therefore, the magnitude of the twist angle around the optical axis A of the light ray R1 and the direction of twist (the direction in which the light ray R1 turns around the optical axis A as indicated by the arc-shaped arrow) are different.

Further, among the intermediate components, there is a light ray that is perpendicular to the side S (parallel to the normal line of the side S), such as a light ray R2 shown in FIG. In this case, the incident angle of the light ray R2 with respect to the normal of the side S is 0 °, and the reflection angle at the reflection point P1 is also 0 °. Since the base point of the light ray R2 is the optical axis A (light emission center OP), when the reflection angle is 0 °, the locus after reflection at the reflection point P1 of the light ray R2 is the same as the incident locus to the reflection point P1. It becomes. Therefore, the light ray R2 only repeats reflection between the first incident side S and the opposite side S, and no twist about the optical axis A occurs.

As described above, the light beam included in the incident beam BMin includes a light beam that does not twist around the optical axis A like the light beam R2 in the beam shaping unit 73. However, the short-axis component RS and the long-axis component RL are included. Since most of the light rays including the incident light are incident on the side S at an angle other than perpendicular, the light rays are twisted around the optical axis A. Moreover, the magnitude | size of a twist angle is various. This means that the radiation direction of each light beam included in the incident beam BMin is dispersed in a cross section orthogonal to the optical axis A by internal reflection in the beam shaping unit 73.

As a result of such dispersion action, as shown in FIG. 26, the incident beam BMin having a substantially elliptical cross-section at the time of incidence is the circular shape of the outgoing beam BMout at the time of emission emitted from the emission end 73c. Will be shaped.

FIG. 27 is a graph obtained by measuring the intensity distribution of the outgoing beam BMout under the same conditions as in FIG. As shown in FIG. 19, in the incident beam BMin, there is a difference between the two such that the divergence angle θxin in the X direction is narrow and the divergence angle θyin in the Y direction is wide. As a result of the action 73, the divergence angle θxout in the X direction is widened, while the divergence angle θyout in the Y direction is narrowed, so that both substantially coincide as shown in FIG. Thereby, it can be seen that the cross-sectional shape of the outgoing beam BMout is shaped into a substantially perfect circle. Specifically, at the time of incidence, the divergence angle θyin in the Y direction (major axis LA direction) is about 11 ° to 14 °, and the divergence angle θxin in the X direction (short axis SA direction) is about 5 ° to 7 °. The incident beam BMin is shaped into a substantially perfect output beam BMout having a divergence angle θyout = θxout of about 10 ° by the shaping action of the beam shaping unit 73.

The graph shown in FIG. 28 shows the intensity distribution of the beam after the outgoing beam BMout further enters the divergence angle correction unit 72 shown in FIG. 16 and exits from the divergence angle correction unit 72. As shown in this graph, the divergence angle θout of the outgoing beam BMout is expanded by the divergence angle correction unit 72. The correction amount of the divergence angle is determined by the size of the tilt angle with respect to the optical axis of the side surface 72b of the divergence angle correction unit 72 and the length of the side surface 72b defining the number of reflections in the optical axis direction. In this example, the divergence angle θ is expanded from about 10 ° to about 20 °, which is almost doubled.

The third light source module 33 is provided with a light emitting element part 76 (see FIG. 10) having a laser diode LD3 (see FIG. 3) instead of the light emitting element part 71 of the second light source module 32, The second light source module 32 has the same configuration. About the divergence angle correction | amendment part 72 and the beam shaping part 73, since it has the same structure and effect | action, description is abbreviate | omitted.

Hereinafter, the operation of the above configuration will be described. When performing an endoscopic diagnosis, the endoscope 11 is connected to the processor device 12 and the light source device 13, the processor device 12 and the light source device 13 are turned on, and the endoscope system 10 is activated.

The insertion part 16 of the endoscope 11 is inserted into the subject's digestive tract, and observation in the digestive tract is started. In the normal observation mode, as shown in FIG. 8A, the first light source module 31 is turned on, and the white light in which the narrow band light N1 emitted from the laser diode LD1 and the fluorescence FL emitted from the phosphor 36 are mixed is observed. Is irradiated.

The cross-sectional shape orthogonal to the optical axis of the narrow-band light N1 emitted from the laser diode LD1 has a substantially elliptical shape, but is shaped into a substantially perfect circle by being diffused in the phosphor 36. Since the fluorescence is emitted from the phosphor 36 having a circular cross section, the cross section of the beam is also substantially circular. Therefore, as shown in FIG. 29, a substantially circular white light (mixed light) beam BM is emitted from the phosphor 36 and is incident on the branch portions 41 a and 41 b of the branch light guide 41. The white light is guided to the exit end 41e of the branched light guide 41 and enters the homogenizer 50 (see FIG. 10).

As shown in FIG. 11, the white light guided from the branch portions 41a and 41b is unevenly distributed on the end face of the emission end 41e. However, as shown in FIG. 12, the light quantity distribution is uniform by the action of the homogenizer 50. It becomes. As a result, white light having no unevenness in the amount of light in the cross section of the beam enters the light guide 43 of the endoscope 11. White light is irradiated from the illumination window 22 to the observation site in the digestive tract through the light guide 43.

As shown in FIG. 8A and FIG. 9A, the observation site is imaged by the imaging device 44 during the irradiation with white light (N1 + FL), and B, G, and R image signals are generated by the DSP 57. In the normal observation mode, the image processing unit 58 generates a display image for normal observation based on the B, G, and R image signals. The display control circuit 60 converts the display image for normal observation into a video signal and displays it on the monitor 14. Such processing is repeated in the normal observation mode.

When performing blood vessel enhancement observation, a mode switching operation is performed by the console 15, and the processor device 12 is set to the blood vessel enhancement observation mode.

In the blood vessel enhancement observation mode, as shown in FIG. 8B, in addition to the first light source module 31, the second light source module 32 is turned on, and white light (N1 + FL) and narrowband light N2 are irradiated to the observation site. As shown in FIGS. 20 and 22, the beam BM of the narrowband light N2 emitted from the laser diode LD2 is incident on the incident end 73a of the beam shaping unit 73, and in the optical axis A direction by internal reflection in the beam shaping unit 73. Light is guided.

As shown in FIG. 19, at the time of incidence, the divergence angles θxin and θyin of the incident beam BMin do not coincide with each other, and the cross-sectional shape is substantially elliptical. As shown in FIG. 20 to FIG. 26, the incident beam BMin causes most of the light beams including the short axis component RS and the long axis component RL to pass through the optical axis A due to internal reflection in the beam shaping unit 73, as shown in FIGS. Twist around. Therefore, the radiation direction of each light beam included in the incident beam BMin changes during light guide and is dispersed at the time of emission. As a result, as shown in FIGS. 26 and 27, the outgoing beam BMout is shaped into a substantially perfect circle having the same divergence angles θxout and θyout, and is emitted from the beam shaping unit 73.

The shaped beam BM enters the incident end 72a of the divergence angle correction unit 72 from the beam shaping unit 73, and the divergence angle θ is widened by the action of the divergence angle correction unit 72 shown in FIG. As a result, the divergence angle θ of the beam BM is expanded from the divergence angle θ shown in FIG. 27 to the divergence angle θ shown in FIG.

As described above, the beam BM of the narrow band light N2 emitted from the laser diode LD2 is shaped into a substantially perfect circle by the beam shaping unit 73, and after the divergence angle θ is widened by the divergence angle correction unit 72, FIG. As shown, the light enters the incident end 41 c of the branched light guide 41. Similar to the white light beam BM emitted from the first light source module 31, the narrow band light N2 beam BM is shaped into a substantially circular cross section, and the divergence angle θ is also equal to the divergence angle of the white light beam BM. Correction is made so that they are almost the same.

The white light and the narrowband light N2 enter the branch portions 41a, 41b, and 41c of the branch light guide 41, are guided to the output end 41e, and enter the homogenizer 50, respectively. The white light and the narrow-band light N2 are supplied to the light guide 43 of the endoscope 11 after the light quantity distribution is made uniform by the homogenizer 50. The white light and the narrow band light N2 are irradiated from the illumination window 22 to the observation site in the digestive tract through the light guide 43.

As shown in FIG. 8B and FIG. 9B, the observation site is imaged by the imaging device 44 during irradiation with white light (N1 + FL) and narrowband light N2, and B, G, and R image signals are generated by the DSP 57. In the blood vessel enhancement observation mode, as in the normal observation mode, the image processing unit 58 generates a display image for blood vessel enhancement observation based on the B, G, and R image signals. The display control circuit 60 converts a display image for blood vessel enhancement observation into a video signal and displays it on the monitor 14. Such processing is repeated in the blood vessel enhancement observation mode. In the blood vessel enhancement observation mode, the image signal B includes a signal corresponding to the narrowband light N2 in addition to the B component of white light, so that the superficial blood vessels are depicted with high contrast in the observation image.

In the blood vessel enhancement observation mode, the white light and the narrowband light N2 emitted from the first and second light source modules 31 and 32 are used, and the light source modules 31 and 32 are respectively divergence angles by the divergence angle correction units 64 and 72. Are corrected so as to substantially match. Therefore, as shown in FIG. 17, the sizes of the irradiation spots of the white light beam and the narrow-band light N2 that are irradiated on the observation region SB substantially coincide with each other. Further, since the second light source module 32 shapes the cross-sectional shape of the beam into a substantially perfect circle shape by the beam shaping unit 73, the irradiation spot shape of the narrow band light N2 is the irradiation spot of the white light emitted from the first light source module 31. Since the shape is the same, an observation image without color unevenness can be obtained.

When performing the oxygen saturation observation, a mode switching operation is performed from the console 15 and the operation mode of the processor device 12 is set to the oxygen saturation observation mode.

In the oxygen saturation observation mode, as shown in FIG. 8C, the first light source module 31 and the third light source module 33 are alternately turned on every frame, and white light (N1 + FL) and narrowband light N3 are alternately turned on. Irradiated to the observation site.

The corrected white light and narrowband light N3 enter the branch portions 41a, 41b, and 41d of the branch light guide 41 at each irradiation timing, are guided to the exit end 41e, and enter the homogenizer 50. The white light and the narrowband light N3 are supplied to the light guide 43 of the endoscope 11 after the light amount distribution is uniformized by the homogenizer 50. The white light and the narrow band light N3 are sequentially irradiated from the illumination window 22 to the observation site in the digestive tract through the light guide 43.

As shown in FIGS. 8C and 9C, the image sensor 44 sequentially outputs image signals corresponding to white light (N1 + FL) and narrowband light N3 to the DSP 57. The DSP 57 generates an image signal of each color of B1, G1, and R1 based on the image signal acquired under the white light, and generates an image signal of B2 based on the image signal acquired under the narrowband light N3. Is generated. The image processing unit 58 calculates the oxygen saturation with the blood volume information separated by performing an inter-image calculation of the image signals B2, G1, and R1. Then, the full color image generated based on the image signals B1, G1, and R1 is subjected to color conversion in accordance with the calculated oxygen saturation value to generate a display image for oxygen saturation observation.

Thus, in the oxygen saturation observation mode, the first and third light source modules 31 and 33 are used. Similarly to the second light source module 32, the third light source module 33 shapes the cross-sectional shape of the beam BM of the narrowband light N3 into a substantially true circle by the beam shaping unit 73, and widens the divergence angle by the divergence angle correction unit 72. . For this reason, the white light and the narrow-band light N3 emitted from the light source modules 31 and 33 have the same irradiation spot size and irradiation spot shape, so that no color unevenness occurs in the observation image. In the oxygen saturation observation mode, unlike the blood vessel enhancement observation mode, the image signals corresponding to the white light and the narrowband light N3 are acquired in the frame order, but the inter-image calculation is performed based on the respective image signals. Therefore, by eliminating the color unevenness between the white light and the narrow-band light N3, the reliability of the inter-image calculation is also improved.

In the present invention, since the beam shaping is performed by the beam shaping unit 73 formed of the light guide rod, a combination of two lenses of a coupling lens and a condenser lens having two cylindrical surfaces, Compared to the prior art (Patent Document 2) that performs beam shaping by combining two lenses, such as a combination of cylindrical lenses, the number of interfaces with air is reduced, so Fresnel loss is reduced and light transmission efficiency is reduced. Can be reduced. When two lenses are used, high accuracy is required for alignment accuracy such as optical axis alignment. On the other hand, when a light guide rod is used, the accuracy is not as high as that of a lens, so that the assemblability is good. In addition, there is an advantage that the number of parts is small as compared with the case of using two lenses.

In the above example, as shown in FIG. 18, in the beam shaping unit 73 having a hexagonal cross-sectional shape, the angle φL of the hexagonal axis A1 and the axis A2 is inclined by 15 ° with respect to the X direction and the Y direction. As described above, the angle φL does not have to be 15 °, and may be any angle in the range of 0 ° to 60 °.

FIG. 30 shows an example in which the angle φL = 0 °. When the angle φL is 0 °, the short axis component RS and the axis A2 of the light beam included in the incident beam BMin coincide with the long axis component RL and the axis A1. In this case, since the short-axis component RS having the optical axis A as the base point is incident perpendicular to the hexagonal side S, the reflection angle at the first reflection point Px1 (angle with respect to the normal of the side S) is 0. It becomes °. For this reason, the short-axis component RS reciprocates between two opposing reflection points Px1, and no twist about the optical axis A occurs.

On the other hand, since the long axis component RL is incident on the hexagonal apex, the apex becomes the first reflection point Py1. Since the major axis component RL and the vertex intersect with each other at an angle other than vertical, they intersect with each other. Therefore, since the reflection angle is 0 ° or more at the reflection point Py1, the long axis component RL is twisted around the optical axis A. Further, the intermediate component between the short axis component RS and the long axis component RL is also twisted around the optical axis A because it is incident on the side S at an angle other than perpendicular. As a result, the light rays included in the incident beam BMin are dispersed in a cross section orthogonal to the optical axis A, so that the cross-sectional shape of the beam BM is shaped into a substantially perfect circle.

FIG. 31 shows an example in which the angle φL = 30 °. In this case, contrary to the example of FIG. 30, the long axis component RL is incident perpendicular to the side S, so that no twist occurs around the optical axis A, but the short axis component RS is hexagonal. Is the first reflection point Px1 and is incident at an angle other than perpendicular to the side S, so that twist about the optical axis A occurs. Further, the intermediate component between the short-axis component RS and the long-axis component RL is twisted around the optical axis A as in the example of FIG. Thereby, the cross-sectional shape of the beam BM is shaped into a substantially perfect circle.

As described above, it is known from experiments and simulations that if at least one of the short axis component RS and the long axis component RL is twisted around the optical axis A, the beam shaping effect can be obtained. Of course, as shown in FIG. 18, it is preferable that both the short-axis component RS and the long-axis component RL are incident on the side S at an angle other than perpendicular because the shaping effect is high. Among them, in the case of the beam shaping unit 73 having a hexagonal cross section, as shown in FIG. 18, it is known from experiments and simulations that the angle φL is most preferably 15 °.

32, the emission center OP of the incident beam BMin may be offset with respect to the optical axis A, which is the hexagonal center of the beam shaping unit 73. This is because one of the short axis component RS and the long axis component RL (the long axis component RL in the example of FIG. 32) can be incident on the side S at an angle other than perpendicular. Thereby, about one of the short-axis component RS and the long-axis component RL, a twist around the optical axis A is generated, so that a beam shaping effect is obtained. However, when the emission center OP is offset with respect to the optical axis A, there is a demerit that the cross-sectional area of the beam shaping unit 73 has to be increased with respect to the size of the incident beam BMin as compared with the case where there is no offset. . When the incident beam of one light emitting element portion 71 is guided, the disadvantage is large, and it is preferable that the optical axis A and the light emission center OP coincide.

“Second Embodiment”
Like the beam shaping unit 81 shown in FIGS. 33 and 34, the cross-sectional shape may be a quadrangle. The beam shaping unit 81 is the same as the beam shaping unit 73 in terms of material and light guiding function, except that the cross-sectional shape is different. The beam shaping unit 81 is a light guide rod formed of a columnar body having an incident end 81a, an emitting end 81c, and a side surface portion 81b extending in the longitudinal direction from the incident end 81a toward the emitting end 81c. The cross-sectional shape is a square. A beam incident on the incident end 81a from the light emitting element portion 71 is guided in the direction of the optical axis A by total reflection on the inner surface (reflection side surface) of the side surface portion 81b, and is emitted from the emission end 81c.

The beam shaping unit 81 is arranged so that the optical axis A and the light emission center OP of the laser diode LD2 coincide with each other. Further, in the beam shaping unit 81, two orthogonal axes connecting two opposing vertices of the quadrangle are respectively in the X direction (the short axis direction of the incident beam BMin) and the Y direction (the long axis direction of the incident beam BMin). Are arranged to match. This is a posture in which two opposite sides of the square are rotated by 45 ° around the optical axis A with respect to the normal posture (see FIG. 36) arranged so as to be parallel to the X direction and the Y direction. is there.

By setting the beam shaping unit 81 in such an attitude, the first reflection points Px1 and Py1 of the short-axis component RS and the long-axis component RL of the incident beam BMin become two opposing vertices of a square. Each of the short-axis component RS and the long-axis component RL and the quadrangular vertex intersect with each other at an angle other than vertical, so that they intersect with each other. Therefore, the short-axis component RS and the long-axis component RL radiated from the optical axis A are incident on the reflection points Py1 and Px1, respectively, and twisting around the optical axis A occurs. This produces a beam shaping effect that makes the substantially elliptical incident beam BMin substantially circular.

As shown in FIG. 35, the beam shaping unit 81 may be in a posture inclined by an angle φL around the optical axis A from the posture with reference to the posture of FIG. The angle φL is 5 °, for example. This posture is a posture inclined about 40 ° with respect to the normal posture (see FIG. 36). In this posture, the short-axis component RS and the long-axis component RL are incident on the sides S at angles other than perpendicular at the first reflection points Px1 and Py1. This produces a beam shaping effect that makes the substantially elliptical incident beam BMin substantially circular.

When the cross section of the beam shaping unit 81 is a square, as shown in FIG. 36, which is a comparative example of the present invention, in a normal posture where two opposite sides of the square are parallel to the X direction and the Y direction, respectively. It is known from the results of experiments and simulations that a good beam shaping effect cannot be obtained. This is because, as shown below, in the positive posture, both the short axis component RS and the long axis component RL are perpendicularly incident on the side S, so that no twist around the optical axis A occurs at the reflection point. The reason is considered.

As shown in FIG. 36, when the beam shaping unit 81 is in the positive posture, the short axis component RS and the long axis component RL are incident perpendicular to the side S at the first reflection points Px1 and Py1. become. Therefore, the short axis component RS and the long axis component RL are not twisted around the optical axis A. The same applies to the second and subsequent reflections. Therefore, the short axis component RS and the long axis component RL do not change in the radial direction at both the incident time and the outgoing time, and the short axis component RS is in the X direction and the long axis component RL is in the Y direction at the outgoing time. Emitted.

Of course, even in the normal posture, the intermediate component between the short axis component RS and the long axis component RL of the incident beam BMin is incident at an angle other than perpendicular to the side S. The surrounding twist occurs. However, the short-axis component RS and the long-axis component RL that define a substantially elliptical shape are not shaped into a substantially perfect circle because twisting around the optical axis A does not occur.

As described above, the beam shaping unit 81 cannot obtain a good beam shaping effect when arranged in the normal posture, but if the posture is slightly inclined from the normal posture, the short axis component RS and the long axis component RL are obtained. Both are incident at an angle other than perpendicular to the side S, so that a good beam shaping effect can be obtained. According to the results of experiments and simulations, the most preferable posture among them is a posture inclined by 45 ° with respect to the normal posture, as shown in FIG.

Further, as described in the hexagonal beam shaping unit 73, the emission center OP of the incident beam BMin may be offset with respect to the optical axis A that is the center of the quadrangle of the beam shaping unit 81. Even in this case, if the posture is other than the normal posture, one of the short axis component RS and the long axis component RL can be incident on the side S at an angle other than perpendicular. However, as compared with the case where there is no offset, there is a demerit that the cross-sectional area of the beam shaping unit 73 must be increased with respect to the size of the incident beam BMin, so that the beam of one light emitting element unit 71 is guided. In some cases, it is preferable that the optical axis A and the light emission center OP coincide.

In this example, a square is illustrated as a quadrangle, but a rectangle or a parallelogram may be used. Of course, it is considered that a square is the easiest to create. Therefore, the square is most preferable in consideration of manufacturing aptitude.

“Third Embodiment”
Like the beam shaping unit 86 shown in FIGS. 37 and 38, the cross-sectional shape may be a triangle. The beam shaping unit 86 is the same as the beam shaping units 73 and 81 in terms of material and light guiding function, except that the cross-sectional shape is different. The beam shaping unit 86 is a light guide rod formed of a columnar body having an incident end 86a, an exit end 86c, and a side surface portion 86b extending from the incident end 86a toward the exit end 86c. The cross-sectional shape is an equilateral triangle. A beam incident on the incident end 86a from the light emitting element portion 71 is guided in the direction of the optical axis A by total reflection on the inner surface (reflection side surface) of the side surface portion 86b, and is emitted from the emission end 86c.

The beam shaping unit 86 is arranged with the light emission center OP and the optical axis A aligned. Further, as shown in FIG. 38, the beam shaping unit 86 is arranged in a normal posture with one vertex upward, one side facing the vertex downward, and the lower side parallel to the X direction. .

When the beam shaping unit 86 is arranged in this way, one of the long axis components RL of the incident beam BMin is a vertex, and the other side S is the first reflection point Py1. The long axis component RL crosses the vertex. The long axis component RL is incident on the side S perpendicularly, but the major axis component RL incident perpendicularly to the side S is reflected perpendicularly on the side S and incident on the apex. The second reflection point Py2 is a vertex. Since the incident angle of the light beam is an angle other than vertical at the apex, the major axis component RL is twisted around the optical axis A. On the other hand, the short axis component RS is incident on two opposing sides S. Since the two opposing sides and the short axis component RS are obliquely crossed, the light enters the reflection point Px1 at an angle other than perpendicular. Therefore, twisting around the optical axis A occurs. In this way, twisting around the optical axis A occurs with respect to both the short axis component RS and the long axis component RL. Therefore, a beam shaping action that makes the cross-sectional shape of the incident beam BMin a substantially circular shape occurs.

Further, as shown in FIGS. 39 and 40, the beam shaping unit 86 may have a posture other than the normal posture shown in FIG. 39 shows a posture rotated by 180 ° from the normal posture around the optical axis A, and FIG. 40 shows a posture inclined by about 5 ° from the posture of FIG. Since a triangle is a point object unlike a hexagon or a quadrangle, any direction of inclination causes a twist around the optical axis A to change the radiation direction for both the short axis component RS and the long axis component RL. Can be made.

When the cross-sectional shape is a triangle like the beam shaping unit 86, the light emission center OP may be offset with respect to the optical axis A. Further, although an example of an equilateral triangle has been described in this example, it may not be an equilateral triangle, and may be a right triangle or an isosceles triangle. Of course, the equilateral triangle is considered to be most easily created, and therefore the equilateral triangle is most preferable in consideration of the suitability for manufacturing.

In the first to third embodiments, the cross-sectional shape of the beam shaping unit has been described as an example of a hexagon, a quadrangle, or a triangle, but it may be a pentagon or a polygon more than a hexagon. However, when the beam shaping portion has a diameter of several millimeters or less, it is preferable that the diameter is not more than a hexagon in consideration of manufacturability.

“Fourth Embodiment”
Further, the cross-sectional shape of the beam shaping unit may not be a polygon. For example, a perfect circle may be sufficient as a cross-sectional shape like the beam shaping part 91 shown to FIG.

The beam shaping unit 91 is the same as the beam shaping units 73, 81, and 86 in terms of material and light guiding function, except that the cross-sectional shape is different. The beam shaping unit 91 is a light guide rod formed of a columnar body having an incident end 91a, an exit end 91c, and a side surface portion 91b extending from the incident end 91a toward the exit end 91c. A beam incident on the incident end 91a from the light emitting element portion 71 is guided in the direction of the optical axis A by total reflection on the inner surface of the side surface portion 91b, and is emitted from the emission end 91c. Since the cross-sectional shape of the beam shaping unit 91 is a perfect circle, the inner surface of the side surface portion 91b that serves as a reflective side surface is configured by a curved surface.

As shown in FIG. 42, the beam shaping unit 91 is arranged with the emission center OP of the laser diode LD2 offset from the optical axis A of the beam shaping unit 91. The emission center OP is offset with respect to the optical axis A in both the X direction and the Y direction. Due to the offset, the first reflection point of the short-axis component RS is Px1, but the tangent TL of the reflection point Px1 and the short-axis component RS are not orthogonal. Therefore, at the reflection point Px1, the inner surface (reflection side surface) of the side surface portion 91 and the short axis component RS are obliquely crossed, and the short axis component RS has a reflection angle when reflected at the reflection point Px1. As a result, twisting around the optical axis A occurs, and the radiation direction of the short-axis component RS changes. Also for the long axis component RL, the first reflection point is Py1, but the tangent TL of the reflection point Py1 and the long axis component RL are not orthogonal. Therefore, the inner surface (reflection side surface) of the side surface portion 91 and the long axis component RL are obliquely crossed, and the long axis component RL has a reflection angle when reflected at the reflection point Py1. As a result, twisting around the optical axis A occurs, and the radiation direction of the long axis component RL changes. By such an operation, a beam shaping effect that makes the cross-sectional shape of the beam substantially circular is obtained.

When the cross-sectional shape is a perfect circle like the beam shaping unit 91, offsetting the emission center OP with respect to the optical axis A is an essential condition for obtaining the beam shaping effect. As shown in FIG. 43 as a comparative example, when the optical axis A of the beam shaping unit 91 and the light emission center OP coincide with each other, in Px1 and Py1 that are the first reflection points of the short axis component RS and the long axis component RL, The tangent line TL is orthogonal to the short axis component RS and the long axis component RL. Therefore, twisting around the optical axis A does not occur. Further, when the cross-sectional shape of the beam shaping unit 91 is a perfect circle, if there is no offset and the optical axis A and the light emission center OP coincide with each other, an intermediate component between the short axis component RS and the long axis component RL is obtained. Since no change in the radiation direction occurs, a beam shaping effect cannot be expected, and a substantially elliptical beam that is the same as the incident beam BMin is emitted from the emission end 91c.

In the example of FIG. 42, the emission center OP is offset in both the X direction and the Y direction with respect to the optical axis A of the beam shaping unit 91. However, as shown in FIG. It may be offset only in the parallel X direction, or may be offset only in the Y direction parallel to the long axis component RL as shown in FIG. It has been confirmed by experiments and simulations that the beam shaping effect can be obtained even when the offset is performed in only one direction. Of course, offsetting in the two directions of the X direction and the Y direction is preferable because the beam shaping effect is high.

In this example, the beam shaping unit having a true circular cross section has been described as an example, but an elliptical shape may be used. Further, an oval shape in which a part of the inner surface of the side surface portion is a flat surface may be used (see FIG. 48).

“Fifth Embodiment”
Like the beam shaping unit 94 shown in FIGS. 46 and 47, incident beams from a plurality of light emitting element units 71 may be guided. The beam shaping unit 94 has a perfect cross-sectional shape, and the incident surface has a size that can receive the incident beams BMin of the four light emitting element units 71. Other points such as the material and the light guiding function are the same as those of the beam shaping unit 91.

As described in the fourth embodiment, in the case of a beam shaping section having a perfect cross-sectional shape, it is an essential condition to offset the light emission center OP with respect to the optical axis A. In the case where a plurality of incident beams BMin are shaped by one beam shaping unit, as shown in FIG. 47, a plurality of light emitting element units 71 are arranged at one incident end. The light emission center OP of each light emitting element unit 71 is offset with respect to the optical axis A. As described above, in the case of guiding the one incident beam BMin, there is a demerit that the cross-sectional area becomes larger when the one incident beam BMin is guided. In the case where the incident beam BMin is guided, an offset is necessary due to layout restrictions, which is effective.

Further, like the beam shaping unit 96 shown in FIG. 48, the cross-sectional shape may be an oval shape in which a part of the inner surface of the side surface part is a flat surface. Moreover, although illustration is abbreviate | omitted, an ellipse may be sufficient.

“Sixth Embodiment”
Like the beam shaping part 98 shown in FIG. 49, you may provide a divergence angle correction | amendment function by tapering the side part 98b. The beam shaping unit 98 is a light guide rod having an incident end 98a, an emission end 98c, and a side surface portion 98b extending from the incidence end 98a to the emission end 98c, and is configured by a columnar body having a square cross section. The beam shaping portion 98 is tapered with respect to the optical axis A at the side surface portion 98b, and has a tapered shape in which the incident end 98a is thinner than the emission end 98c. By tapering the side surface portion 98b in this manner, the beam shaping portion 98 is provided with the same divergence angle correction function as the divergence angle correction portion 72 (see FIGS. 15 and 16).

According to this, since it is not necessary to provide the divergence angle correction unit 72 separately from the beam shaping unit, the number of parts can be reduced and the space can be saved as compared with the first to fifth embodiments. On the other hand, since it is difficult to produce a taper on the side surface portion, it is advantageous to form the side surface portion parallel to the optical axis as in the first to fifth embodiments in terms of manufacturability.

The beam shaping unit 98 has a square cross-sectional shape, but may of course be a polygon other than a quadrangle such as a hexagon or a triangle. Further, like the beam shaping unit 99 shown in FIG. 50, the cross-sectional shape may be circular. However, when the cross-sectional shape is a perfect circle, it is necessary to offset the light emission center OP with respect to the optical axis A as in the embodiment shown in FIG.

The table shown in FIG. 51 includes, in addition to the evaluation results evaluated from the two viewpoints of the suitability for manufacturing and the ease of relative alignment with the light emitting elements, for the beam shaping sections of the first to sixth embodiments. This is a summary of the evaluation results of comprehensive evaluation. As for manufacturing aptitude, the applicability of products having a light guide rod diameter on the order of several millimeters or less is evaluated. Manufacturability in the case of no taper where the side surface portion is not tapered is very good (evaluation A) and the triangle is somewhat bad (evaluation C) except for the cross section of the triangle. As for the hexagonal shape, a hexagonal prism as a light guide rod exists as an off-the-shelf product, and it can be used.

製造 Manufacturing aptitude with a taper to taper is worse than without taper regardless of the cross-sectional shape. When compared by cross-sectional shape, manufacturing is very difficult except for the cone. Therefore, the evaluation of manufacturing aptitude is good when the cross-sectional shape is circular (evaluation B), and the polygon is bad. Among polygons, quadrangles are the easiest (evaluation C), and triangles and hexagons are very difficult (evaluation D).

Regarding the evaluation of the ease of alignment, the circular shape is slightly worse (evaluation C) regardless of the presence or absence of a taper, and the others are very good (evaluation A). This is because an offset is required in the case of a circle, whereas an offset may or may not be present in the case of a polygon. Comprehensively, when there is no taper, the hexagon is very good (evaluation A), the circle and the rectangle are good (evaluation B), and the triangle is slightly bad (evaluation C). When there is a taper, the evaluation is that a square is good (evaluation B), a circle and a hexagon are slightly bad (evaluation C), and a triangle is bad (evaluation D).

In the above embodiment, the beam shaping unit, which is the optical element of the present invention, has been described in the form of a light guide rod formed of a columnar body. However, as shown in FIG. Alternatively, the mirror pipe 101 may be formed. Even in the mirror pipe 101, the incident beam can be guided in the optical axis direction by being reflected by the mirror surface 102 which is the inner surface of the side surface portion inside the hollow. Then, if the cross-sectional shape orthogonal to the optical axis is a polygon, beam shaping can be performed. Of course, the cross-sectional shape may be circular. In this case, it is necessary to offset the light emission center of the light emitting element with respect to the optical axis. In addition, since the specular reflection has a larger reflection loss than the total reflection, the light guide rod is more advantageous than the mirror pipe 101 in view of light transmission efficiency.

In the above embodiment, the second and third light source modules 32 and 33 that emit narrowband light have been described as examples of the light source unit using the beam shaping unit. However, the color of the beam and the emission wavelength are not limited to the above example. It can be changed as appropriate. Moreover, the light source part which uses beam shaping parts, such as the 2nd, 3rd light source modules 32 and 33, is used in combination with the 1st light source module 31 which emits white light as a light source part which does not use a beam shaping part. Of course, a combination with another light source unit may be used. For example, in a light source device that generates white light using three light source units that emit monochromatic light of B, G, and R, a beam shaping unit may be used for at least one light source unit of B, G, and R.

Further, the first light source module 31 has been described as an example of a light source unit that emits a substantially circular beam without using a beam shaping unit. However, a light source unit that emits a substantially circular beam is as in the first light source module 31. In addition, the phosphor and the light emitting element may not be combined. For example, a light emitting element such as an LED or an EL other than the laser diode may be used. Further, a light source such as a xenon lamp or a halogen lamp may be used.

In the above embodiment, the laser diode is described as an example of the light emitting element of the light source unit using the beam shaping unit, but the beam shaping unit may be applied to other light emitting elements such as an LED and an EL (electroluminescence). Since LEDs and EL generally emit a substantially circular beam, the need for beam shaping is low, but among light emitting elements using LEDs and EL, a substantially elliptical beam is emitted depending on the type and specification. In some cases. In such a case, the need for beam shaping arises, so the beam shaping unit of the present invention may be applied.

In the above embodiment, the optical shaping element has been described by taking the beam shaping unit for shaping a substantially elliptical beam into a substantially perfect circle as an example, but the cross-sectional shape of the incident beam as a shaping source may be other than an elliptical shape. In this case, the beams may have different divergence angles in the first direction and the second direction orthogonal to the first direction. The optical element only needs to have a reflective side surface that is oblique to at least one of the first direction and the second direction, and the cross-sectional shape after shaping may not be a perfect circle.

In the above-described embodiment, an example of a simultaneous method in which white light is color-separated by a micro color filter and a plurality of color images are simultaneously acquired using a color image sensor provided with B, G, and R micro color filters is described. However, the present invention may be applied to a frame sequential method in which images of respective colors are sequentially acquired using a monochrome imaging element not provided with a color filter.

In the above embodiment, the example in which the light source device and the processor device are configured separately is described, but the two devices may be configured integrally. In addition, the present invention can be applied to other types of endoscope systems such as a system including an ultrasonic endoscope in which an imaging element and an ultrasonic transducer are built in a distal end portion and a processor device that performs image processing. it can.

In the above embodiment, the beam shaping unit is applied to the endoscope light source device, but the beam shaping unit may be applied to a device other than the endoscope light source device. Examples of devices other than the endoscope light source device include an electron microscope light source device. Also in an electron microscope, in order to observe a living tissue in the same manner as an endoscope, a plurality of light beams that emit a plurality of lights having different wavelengths, like the first to third light source modules 31 to 33 described in the above embodiment. In some cases, a light source unit is provided. In such a case, the beam shaping unit of the present invention is effective.

“Seventh Embodiment”
In addition to the light source device for an electron microscope, the present invention may be applied to a projector device shown in FIG. The projector device 110 is a device that displays an image by projecting light carrying image information on a screen.

The projector device 110 includes a light source unit 113 having a light emitting element unit 111 having a laser diode LD and a beam shaping unit 112. An imaging lens 114 and a light modulation element 115 are arranged in front of the light source unit 113. The imaging lens 114 focuses the beam emitted from the light source unit 113 and forms an image on the light modulation element 115. The light modulation element 115 includes a liquid crystal element or a DMD (digital micromirror device) element in which cells corresponding to pixels are arranged in a matrix. The light modulation element 115 drives each pixel based on the image data, modulates the imaged light, and generates image light carrying image information. The generated image light is projected onto the screen and an image is displayed.

The beam shaping unit 112 is the beam shaping unit of any of the first to sixth embodiments, and shapes the cross-sectional shape of the incident beam from the laser diode LD from a substantially elliptical shape to a substantially perfect circular shape. By this beam shaping action, the irradiation spot shape of the light imaged on the light modulation element 115 can be made circular.

As an application example of the light source unit having the beam shaping unit 112, in addition to the projector device, for example, in an optical disc device that reads information by irradiating light on a disc on which information is recorded, light constituting a reading unit You may apply to a pick-up apparatus.

DESCRIPTION OF SYMBOLS 10 Endoscope system 11 Endoscope 12 Processor apparatus 13 Light source apparatus 28 Connector 31 1st light source module 32 2nd light source module 33 3rd light source module 36 Phosphor 41 Branch type | mold light guide 41a-41d Branch part 41e Output end 42 Receptacle Connector 43 Endoscope light guide 50 Homogenizer 61 Laser module 62 Fluorescence part 64, 72 Divergence angle correction part 66, 71, 76 Light emitting element part 73, 81, 86, 91, 94, 96, 98, 99 Beam shaping part ( Optical element)
73a Incident end 73b Side surface portion 73c Emission end A Optical axis BM Beam BMin Incident beam BMout Emission beams LD1 to LD3 Laser diodes (light emitting elements)
OP emission center

Claims (16)

1. A light-emitting element that emits a diverging beam, and the beam is a light-emitting element having different divergence angles in a first direction and a second direction perpendicular to the first direction in a cross section thereof;
   An incident surface on which a beam emitted by the light emitting element is incident; an exit surface that emits the incident beam; and a longitudinal axis that extends in a longitudinal direction from the incident surface toward the exit surface. An optical element that propagates in the longitudinal direction while being reflected internally, and has a reflective side surface that is oblique to at least one of the first and second directions of the beam in a plane perpendicular to the longitudinal axis. A light source device comprising an optical element.
2. The optical element reflects at least one of a first component and a second component parallel to each of the first direction and the second direction among the light rays included in the beam by reflection on the reflection side surface. The light source device according to claim 1, wherein twisting around an axis is generated.
3. The optical element is a light guide rod made of a columnar body made of a transparent material, the reflection side surface is a boundary surface with air, and the reflection is total reflection. The light source device according to item.
4. 4. The light source device according to claim 3, wherein in the optical element, a cross-sectional shape orthogonal to the longitudinal axis is a polygon, and the reflection side surface is a flat surface.
5. The light source device according to claim 4, wherein the polygon is any one of a hexagon, a quadrangle, and a triangle.
6. The polygon is a hexagon;
   6. The optical element according to claim 5, wherein an axis connecting two opposite vertices of the hexagon is arranged in a posture inclined with respect to the first direction or the second direction. The light source device described.
7. The light source device according to claim 6, wherein an inclination angle of the axis with respect to the first direction or the second direction is 15 °.
8. The polygon is a rectangle,
   The light source device according to claim 5, wherein the optical element is arranged such that each side of the quadrangle is inclined with respect to a normal posture parallel to the first direction or the second direction. .
9. The light source device according to claim 8, wherein an inclination angle with respect to the normal posture is 45 °.
10. The light source device according to claim 4, wherein the optical element is arranged in a state where the center of the polygonal cross section coincides with the light emission center of the light emitting element.
11. 4. The light source device according to claim 3, wherein the area of the incident surface of the optical element has a size that allows light from a plurality of the light emitting elements to be incident thereon.
12. The light source device according to claim 3, wherein the optical element has a tapered shape in which the reflection side surface is inclined with respect to the longitudinal axis.
13. The shape of the cross section of the beam emitted from the light emitting element is an ellipse having a major axis and a minor axis corresponding to the first direction and the second direction, respectively.
    The light source device according to any one of claims 1 to 12, wherein the optical element shapes the elliptical beam incident on the incident surface into a perfect circle and emits the light from the emission surface. .
14. 14. The light source device according to claim 13, wherein the light emitting element is a laser diode.
15. The first light source unit that emits a beam having a perfectly circular cross section without using the optical element, the light emitting element and the optical element, and the shape of the cross section shaped by the optical element is The light source device according to claim 14, comprising at least two types of light source parts of a second light source part that emits a perfect circular beam.
16. 16. The light source device according to claim 15, wherein the first light source unit includes the light emitting element and a phosphor that emits fluorescence when excited by light emitted from the light emitting element.

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