JP4394811B2 - Optical system device for tip of electronic endoscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is the endoscope distal end portion for observing the optical device of the electronic endoscope tip to illuminate the object to be observed in particular through the light guide, the object to be observed which is captured by the image sensor via the objective optical system This relates to the configuration of the optical system member.
[0002]
[Prior art]
In the electronic endoscope apparatus, the object to be observed (inside) is illuminated by emitting light from the distal end of the scope through a light guide made of an optical fiber bundle, and the image of the object to be observed is captured via the objective optical system. The image is picked up by the image sensor. In this type of electronic endoscope apparatus, for example, two light guides are provided up to the tip, and the objective optical system is disposed at a position sandwiched between the two light guides, whereby the object to be observed is arranged. Is designed to illuminate well.
[0003]
By the way, in the electronic endoscope apparatus, since the scope is inserted into an observation site such as a thin body cavity, the diameter of the distal end portion and the insertion portion is required to be reduced. Is made smaller, the arrangement is devised, and the like. However, bright illumination light is necessary for good observation, and it is not a good idea to make the light guide too thin.
[0004]
Moreover, with such an endoscope, it is relatively difficult to perform uniform illumination without unevenness on the imaging position captured by the objective optical system. That is, as described above, when two light guides are provided, since both lights overlap at a predetermined position, illumination unevenness occurs in the peripheral portion. Further, in the case where there is one light guide, strictly speaking, since light strikes obliquely with respect to the irradiation position, illumination unevenness similarly occurs in the peripheral portion.
Therefore, the applicant of the present application has proposed an apparatus that uses an objective optical system member that captures an object image as an illumination optical path as disclosed in Japanese Patent Laid-Open No. 10-99268.
[0005]
[Problems to be solved by the invention]
However, in this electronic endoscope optical system apparatus, a semi-transmissive film is used in the optical path coupling optical element for securing the optical path from the light source and the optical path leading to the imaging element. There is a disadvantage that the output light of the light source cannot be used effectively because it becomes about 1/4 of the light. That is, the light source light becomes 1/2 when passing through the semi-transmissive film, and becomes 1/2 when light from the object to be observed is reflected by the semi-transmissive film. 4
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a distal end portion of an electronic endoscope that can effectively use light source output light even in a configuration in which an objective optical system is used as an observation optical path and an illumination optical path. An optical system apparatus is provided.
[0007]
[Means for Solving the Problems]
To achieve the above object, the optical system device of an electronic endoscope tip according to the invention of the first aspect, wherein is arranged in the endoscope tip portion captures the object under observation image illuminated with illumination light a pair product optical member that, in this side of the objective optical system member is disposed in the distal end portion, provided with a polarizer function of separating into two orthogonal polarization components of light that is incident to one another, the one polarization component A polarization separation optical element that secures a transmission optical path to transmit and a reflection optical path to reflect the other polarization component, and a light source light that is optically connected to either the transmission optical path or the reflection optical path set by the polarization separation optical element A light guide for guiding the light to the tip, an imaging device optically connected to the other end of the optical path, and a polarization component conversion arranged on the front side of the polarization separation optical device to convert linearly polarized light and circularly polarized light includes a device, a from a light source The and outputs via the polarization separating optical element, the polarization component conversion element and an objective optical member from said light guide.
[0008]
According to a second aspect of the present invention, there is provided a total conversion type polarization component conversion element that has a polarizer function of the polarization separation optical element and converts all of the light source light into one linearly polarized light component, the light guide and the polarization separation optical. It arrange | positions between elements .
[0009]
According to the above configuration, random light guided from the light source via the light guide is separated into s-polarized light and p-polarized light by the polarizer function of the polarization separating optical element, for example, only p-polarized light is transmitted, and then It is converted into circularly polarized light by the polarization component conversion element. Then, this circularly polarized light is irradiated as illumination light to the object to be observed through the objective optical system. On the other hand, when circularly polarized reflected light reflected from the object to be observed is captured by the objective optical system, the reflected circularly polarized light is converted into s-polarized light by the polarization component conversion element and guided to the polarization separation optical element. In this polarization separation optical element, the s-polarized light is reflected by the polarizer function and supplied to the image sensor, and the observed object image is formed on the imaging surface by the s-polarized light.
[0010]
Accordingly, a uniform and efficient illumination state in which the illumination area and the observation area are matched is obtained, and the random light amount from the light source is only halved by the polarizer, so the light amount is ¼. Compared with a conventional semi-transmissive film, there is an advantage that the output light of the light source can be used effectively.
According to the configuration of the second aspect, since the all conversion type polarization component conversion element that converts all of the light source light into the linearly polarized light component is used, in this case, all of the light source output light can be used for imaging. It becomes possible.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a main configuration of an optical system device for a distal end portion of an electronic endoscope as a first example of the embodiment, and FIGS. 2 and 3 show a configuration of the distal end portion of the electronic endoscope. Yes. 2 and 3, the distal end portion 10 is provided with an objective optical system member (lens barrel portion) 12 held by a holding member 11, and the objective optical system member 12 includes only an objective lens. And a diaphragm, a filter, etc. are included. Further, a forceps port 14 is provided at the distal end surface of the distal end portion 10, and a treatment tool insertion channel 15 is connected to the forceps port 14, and various treatment tools such as forceps are passed from the forceps port 14 through the treatment tool insertion channel 15. Can be derived.
[0012]
Further, as shown in FIG. 1, on the rear side of the objective optical system member 12, a quarter wavelength plate 16 that is a polarization component conversion element and a cubic prism 17 that is a polarization separation optical element in which a polarizer is incorporated. Are connected optically, and a CCD (Charge Coupled Device) 18 as an imaging device is optically connected to the lower side of the cubic prism 17. The CCD 18 is housed and connected in a CCD package 20 sealed with a cover glass 19, and the cover glass 19 is bonded to the lower surface of the prism 17. Note that a wiring pattern is formed in the CCD package 20, and a signal line 21 for connecting to the outside is connected through the wiring pattern.
[0013]
In FIG. 1, the cubic prism 17 is composed of a polarizing prism (polarizing beam splitter) in which two right-angle prisms are joined and the joining surface (inclined surface) is a polarization separating surface 17A. An s-polarization reflection film (linear polarization reflection film) 27 for reflecting (which may be p-polarized light whose polarization direction is different by 90 degrees) is formed. According to this cubic prism 17, random light as light source light is separated into s-polarized light and p-polarized light by the polarization separation surface 17A provided with the s-polarized reflection film 27, while reflecting the s-polarized light upward in the figure, while p Pass polarized light. In addition, a transmission light path (straight forward optical path) L1 for allowing the light source light to pass to the objective optical system member 12 is set, and light incident from the objective optical system member 12 is directed to the CCD 18 which is the lower right angle direction from the polarization separation surface 17A. A reflected light path L2 to be reflected is formed.
[0014]
The quarter-wave plate 16 on the front side of the cubic prism 17 converts the p-polarized light output from the prism 17 into circularly polarized light, and converts the reflected light from the observed object by the circularly polarized light into s-polarized light. To do. Accordingly, an object image to be observed is formed on the CCD 18 through the reflected light path L2 by the s-polarized light emitted from the quarter-wave plate 16.
[0015]
Further, a light guide 25 is disposed on the rear side of the cubic prism 17 via a condenser lens 23 and a diffusion plate 24, and the light guide 25 is connected to a light emitting end of the light source device. The diffusing plate 24 forms a ground glass surface, and serves to prevent the shape of the fiber bundle on the end face of the light guide 25 from being back-projected to the CCD 18 side.
[0016]
The first example has the above configuration, and its operation will be described below. As shown in FIG. 1, the light guided from the light source device through the light guide 25 passes through the diffusion plate 24 and is incident on the rear surface of the cubic prism 17 by the condenser lens 23. This light source light is random light, but this random light is separated into linearly polarized components (s-polarized light and p-polarized light) by the cubic prism 17, one linearly polarized component is transmitted, and the other linearly polarized component is polarized and separated. Reflected upward at the surface 17A. For example, if p-polarized light travels along the transmission optical path L1 (s-polarized light is reflected), the p-polarized light becomes circularly polarized light by the quarter-wave plate 16 and is observed as illumination light through the objective optical system member 12. Since the illumination light passes through the optical path of the objective optical system member 12 that captures the image of the object to be observed, the illumination pattern is optimal for imaging.
[0017]
On the other hand, the observed object image illuminated by the circularly polarized light is captured by the objective optical system member 12, and the circularly polarized light reflected by the observed object passes through the optical path in the objective optical system member 12 and is polarized by the quarter wavelength plate 16. Are converted into s-polarized light different by 90 degrees and supplied to the cubic prism 17. In the cubic prism 17, the s-polarized light is reflected by the polarization separation surface 17A having the s-polarized reflection film 27 to the reflected light path L2 in the perpendicular direction, so that it is reflected on the imaging surface of the CCD 18 as shown in FIG. An image of the object to be observed is formed by s-polarized light.
[0018]
According to such a first example, the random light output from the light source becomes only p-polarized light by the cubic prism 17, and the amount of light is halved, compared to a conventional transflective film in which the amount of light is ¼. The light source light can be used effectively. Basically, as can be understood from FIGS. 2 and 3, the objective optical system member 12 and the light guide 25 are arranged in series instead of in parallel at the distal end portion 10. Is not required, and the tip portion 10 can be reduced in diameter, and an optimal illumination pattern can be obtained in the imaging area, so that illumination unevenness is eliminated and good imaging is possible.
[0019]
In the first example, the s-polarized reflective film 27 is formed as the linearly polarized reflective film of the cubic prism 17, but a p-polarized reflective film may be formed instead. In this case, the cubic (polarized) The prism 17 is configured to transmit s-polarized light and reflect p-polarized light.
[0020]
4 and 5 show the configuration of a second example device according to the embodiment. This second example has a polarizer function and converts all light source light into linearly polarized light. A conversion element is provided. In the second example, the configuration from the objective optical system 12 to the light guide 25 is the same as shown in FIG. 4, and a full conversion type that converts light source light into, for example, p-polarized light between the cubic prism 17 and the light source. A polarization component conversion element 28 is disposed.
[0021]
FIG. 5 shows an example of the configuration of this all-conversion-type polarization component conversion element 28, which is disclosed in Japanese Patent Laid-Open No. 5-72417. In FIG. 5, a cubic prism (polarization beam splitter) 28a that receives light from a light source has a polarization separation surface 28b that transmits, for example, p-polarized light and reflects s-polarized light. Further, a reflection plate 28c is disposed in the optical path of s-polarized light output from the cubic prism 28a, and a half-wave plate 28d is disposed in the reflection light path of the reflection plate 28c.
[0022]
According to such a configuration, random light as light source light is separated into p-polarized light and s-polarized light by the cubic prism 28a, and p-polarized light is output straight, but s-polarized light is guided upward. The s-polarized light is reflected at right angles by the reflecting plate 28c and then converted to p-polarized light by passing through the half-wave plate 28d, and the p-polarized light is guided to the output direction. Therefore, according to the total conversion type polarization component conversion element 28, all of the light source light is converted into p-polarized light and output.
[0023]
Then, the p-polarized light output from the all-conversion-type polarization component converting element 28 is supplied to the cubic prism 17 which is a polarization separation optical element through the light guide 25 and the like, and the incident p-polarized light is input to the cubic prism 17. All are guided to the objective optical system member 12 through the quarter-wave plate 16. Therefore, the second example has an advantage that an object to be observed can be formed on the CCD 18 using all of the light source light without loss.
[0024]
In the above embodiment, the CCD 18 is provided on the lower side of the cubic prism 17 and the light guide 25 is arranged on the rear surface side. However, this relationship is reversed, the light guide 25 is provided on the lower side of the prism 17, and the rear surface side is arranged. The CCD 18 may be disposed on the front side.
[0025]
【The invention's effect】
As described above, according to the present invention, in the optical system device at the distal end portion of the electronic endoscope that also uses the observation optical path of the objective optical system as an illumination optical path, it is provided with a polarizer function that separates into two polarization components, A polarization separation optical element that secures the transmission optical path and reflection optical path and a polarization component conversion element that converts linearly polarized light and circularly polarized light are provided. Light can be used effectively.
[0026]
According to the second aspect of the present invention, since the total conversion type polarization component conversion element for converting all of the light source output light into one linearly polarized light component is provided, all of the light source light is used for imaging the object to be observed. There is an advantage that you can.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a configuration of an optical system device for a distal end portion of an electronic endoscope according to a first example of an embodiment of the present invention.
FIG. 2 is a side cross-sectional view showing the configuration of the distal end portion of the electronic endoscope of the first example.
3 is a view of the front end portion of FIG. 2 as viewed from the rear side.
FIG. 4 is an explanatory diagram illustrating a configuration of an optical system device at a distal end portion of an electronic endoscope according to a second example of an embodiment.
FIG. 5 is a configuration diagram showing an example of a full conversion type polarization component conversion element of a second example.
[Explanation of symbols]
10 ... tip,
12 ... Objective optical system member,
16: 1/4 wavelength plate,
17 ... Cubic prism (polarizing prism),
18 ... CCD,
25 ... Light guide,
27 ... s-polarized reflective film,
28: All conversion type polarization component conversion element.

Claims (2)

Disposed endoscope tip portion, and a pair product optical member Ru capturing the object to be observed image illuminated by the illumination light,
A transmission optical path that transmits one polarized component and the other polarized light that is disposed in the tip portion on the rear side of the objective optical system member and has a polarizer function for separating incident light into two polarized components orthogonal to each other. A polarization separation optical element that secures a reflection optical path for reflecting the component;
A light guide that is optically connected to either the transmitted light path or the reflected light path set by the polarization separation optical element, and guides the light source light to the tip part ;
An image sensor optically connected to the other of the optical paths;
A polarization component conversion element that is disposed on the front side of the polarization separation optical element and converts linearly polarized light and circularly polarized light,
An optical system device at a distal end portion of an electronic endoscope that outputs light from a light source from the light guide via the polarization separation optical element, a polarization component conversion element, and an objective optical system member . A total conversion type polarization component conversion element that has the polarizer function of the polarization separation optical element and converts all of the light source light into one linearly polarized light component is disposed between the light guide and the polarization separation optical element. The optical system apparatus for a distal end portion of an electronic endoscope according to claim 1 .

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