JP2000210247A - Medical endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regular medical endoscope improved in the measured ratio between the background light and fluorescence. SOLUTION: This medical endoscope has illumination devices 7, 8 with a transmitting filter 11 on the short wavelength side for irradiating an area 6 to be examined partly emitting fluorescence, and observation devices 2, 3 and 4 with a transmitting filter 5 on the long wavelength side. One side of rims of the filters 5 and 11 is formed as an interference filter, and the filters are constituted so that they cross each other with the transmittance of the filters 5 and 11 is smaller than the maximum transmittance of each filter in the range of (blue) fluorescence wavelength shorter than the red fluorescence wavelength. The interference filter is constituted so that the angle to the light proceeding direction is adjustable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The invention relates to an endoscope of the kind mentioned in the preamble of claim 1.

[0002]

2. Description of the Prior Art The fluorescent effect is very useful for endoscopic observation of body regions, for example the bladder wall. The tissue contains a trace amount of a fluorescent light-emitting substance that is irradiated and excited by the illumination device of the endoscope. Since the state of fluorescence emission differs depending on the type of tissue, the difference between tissues can be identified, and for example, cancer can be recognized. However, in the case of this autofluorescence, the fluorescent light-emitting substance in the tissue usually has a very weak fluorescence, and can hardly be confirmed with strong irradiation light. In order to enhance the fluorescence effect, it can be achieved by adding a material that induces fluorescence, such as 5-ALA in the case of bladder cancer, from outside the body. One method that has been proven is to treat the tissue with the substance to be identified or converted into a fluorescent material in, for example, cancerous tissue.
As a result, a strong good-looking fluorescent effect is obtained.

[0003] However, in the case of all the fluorescent tests, there arises a problem that very strong light of the lighting device overlaps the fluorescent light. By inserting an appropriate narrow-band filter into the observation device so that only the fluorescence can be seen, ordinary observation light can be suppressed. Therefore, only the fluorescent light can be seen, but the non-fluorescent light, that is, the normal observation light cannot be seen, making it difficult to give an orientation in the body. The best solution in this case is to make the non-fluorescent wavelength region near the visible fluorescent wavelength region visible and to use another colored light different from the fluorescent light so that it can be better discriminated.

[0004] Therefore, German Patent Publication No. 196,396 describes
In an endoscope system of a type known from No. 53, an illumination light path for irradiating an object with illumination light for exciting fluorescent light is provided for cutting light on a longer wavelength side than a wavelength for exciting fluorescent light. A first filter, and an observation optical system for observing the fluorescence, further comprising a second filter for cutting light having a wavelength shorter than the wavelength of the fluorescence, and a long wavelength side edge of the first filter. The section and the short-wavelength side edge of the second filter are crossed so that observation light having a wavelength different from that of the fluorescence can be obtained. Thus, when observing the marked area, for example, a blue background and a red fluorescent light will be seen. The background light is weakened in a narrow band by properly crossing the filter edges, so that the area marked with fluorescence can be seen well while recognizing sufficient background.

[0005]

In the case of the above-mentioned known arrangement, the filter has a fixed edge which is within the range of manufacturing errors, and the edge cannot be adjusted arbitrarily. Therefore, the intensity of the passed background light cannot be adjusted, and depending on the device, a strong background light that weakens the identification of the fluorescent light or a weak background light that weakens the arrangement of the background may be obtained.

A different type of fluorescence microscope is known from US Pat. No. 5,371,624, in which a band-pass interference filter adjusts the angle with respect to the light direction in order to displace the fluorescent light to be observed. Provided to be able.

The present invention has been made in view of the prior art as described above, and has as its object the provision of a conventional medical endoscope with improved measured ratio of background light to fluorescence. What you want to do.

[0008]

SUMMARY OF THE INVENTION The above object is attained by a structure according to the present invention. According to the present invention, the first filter disposed in the illumination optical system that cuts a wavelength longer than the wavelength of the illumination light that excites desired fluorescence, and the observation optical system that cuts a wavelength shorter than the wavelength of the fluorescence, are provided. At least one of the arranged second filters is formed as an interference filter, and the first filter is arranged so that an angle with respect to a traveling direction of light can be adjusted. Therefore, the wavelength position of the edge of the filter can be moved. In the case of an endoscope, this moves the intersection of the two edges. Therefore, at the intersection, the transmittance decreases, increases, or changes, and accordingly, the background light passing through the intersection area of the edge increases or decreases. Therefore, the intensity of the fluorescence can be adjusted optimally during the preparation immediately before the observation. In some cases, it can also be adjusted by the operating handle during the observation, e.g. to brighten the background during the first general observation, to clarify the orientation in the area of interest, and to make the fluorescence range very accurate later The background can be darkened for observation. Since the endoscope according to the present invention can extremely weaken the background light to observe weak autofluorescence,
Particularly suitable for observing autofluorescence. The adjustability of the intensity of the background light can also solve other problems, such as different color sensitivities of the eye on the one hand and the video camera on the other hand. Therefore, for example, in the case of observation with an eye having substantially the same sensitivity for a blue background and red fluorescence, the background light is adjusted to the same intensity as the fluorescence. In the case of a CCD camera with low sensitivity to blue, the background light is enhanced, and in the case of a vidicon camera, the sensitivity to red is reduced.

[0009] The features of claim 2 and especially the arrangement of claim 3 are provided as being suitable. In luminaires with bright light intensities, interference filters with low absorption are preferred for thermal use. Placing the interference filter in the light source is basically advantageous, since it is possible to place a suitable rotating arrangement there.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a diagram schematically showing an endoscope according to the present invention, and FIG. 2 is a graph showing a filter transmittance curve and light intensity with respect to wavelength.

FIG. 1 shows a simplified view of an endoscope having an elongated housing 1 with an objective lens 2 at its distal end and an eyepiece 3 at its proximal end. For example,
The image is transmitted by the rod-shaped lens device or the image guide 4 in the meantime. In the image transmission path, a long-wavelength-side transmission filter 5, which is usually formed as a color glass filter, is disposed at an appropriate position.

For example, an observation area 6 which is a part of a wall of a human bladder into which a long elongated housing 1 of an endoscope is inserted is illuminated with light passing through a light guide fiber bundle 7. You. A light guide fiber bundle 7 extends into the housing 1, penetrates its wall and has an external light source 8.
Lamp 9 in the light source 8 in the illustrated embodiment.
However, an end of the light guide fiber bundle 7 is irradiated by a condenser device having a lens.

In the embodiment, a short wavelength side transmission filter 11 formed as an interference filter is provided in the lens system 10. In this case, light of a predetermined wavelength or less is transmitted,
It is provided in the form of a glass plate with an optical thin film so that no more light is transmitted, in which case the intersection edges are as steep as possible.

As can be seen from FIG. 1, the short-wavelength-side transmission filter 11 is supported so as to be pivotable about an axis 12 in the direction of the arrow, and is provided with an adjusting device (not shown) such as a rotary knob provided outside the housing of the light source 8. Alternatively, the angle position can be adjusted with respect to the traveling direction of the passing light by a foot switch or a switch provided on the hand side of a camera head or the like (not shown) linked to the rotation axis.

FIG. 2 shows filters 5 and 1 in FIG.
The transmittance curve and light intensity for one wavelength are shown.
The short-wavelength-side transmission filter 11 transmits light in a wavelength range equal to or less than the wavelength range characteristic of “blue”, and blocks light having a wavelength longer than that. Conversely, the transmittance curve (5) of the long-wavelength side transmission filter 5 provided in the observation devices 2, 4, and 3 passes only light above this wavelength range. The transmittance curves (5) and (1)
1) crosses at an intersection 13. Accordingly, only light in the wavelength range (blue light) that should be the background light 14 indicated by the broken line out of the light from the broadband light source 8 is passed. The observer sees only the light in the narrow wavelength region to be the background light 14 of the broadband light emitted from the lamp 9 in consideration of both the filters 5 and 11.

The short-wavelength light illuminating the observation area 6 through the short-wavelength side transmission filter 11 excites the fluorescence in a range marked by the fluorescent light, and a fluorescent image indicated by a broken line in the long-wavelength red range. Yields 15. The fluorescent image 15 and the background light 14 can be clearly distinguished by color.

The slopes and intersections 13 of the edges of the filters 5 and 11 determine the height and width of the rays of background light 14. The slope or cutoff wavelength of the edges of both filters is
This means that very high precision is required to set 4 appropriately. The transmission at the intersection 13 is thereby increased or decreased. Thus, a strong or weak background light 14 results. However, the background light 14
It should be as much as possible without exceeding 5.

By rotating the short-wavelength side transmission filter 11 formed as an interference filter around the axis 12, the angular position is changed, and the edge of the transmittance curve (11) in FIG. 2 is indicated by a broken line. Is moved in the light direction. At the same time, the intersection 13 is displaced to increase or decrease the transmittance, and the background image is strengthened or weakened. The intensity ratio between the background light 14 and the fluorescence image 15 can be adjusted to a predetermined intensity ratio by an appropriate angular position of the short-wavelength side transmission filter 11.

FIG. 3 shows how the transmittance characteristic changes with a change in the rotation angle of the short wavelength transmission filter 11. Filter 11, for example, a dielectric multilayer film made of SiO ₂ and TiO _2, the cut-off wavelength at the incident angle of 0 degrees is about 450nm. Incident angle from 0 degree to 10,20,
As the angle changes to 30 degrees, the cutoff wavelength shifts to the shorter wavelength side in proportion to approximately sin θ.
nm. As described above, generally, by tilting the interference filter, the cutoff wavelength is shifted only to the short wavelength side. Therefore, when an interference filter is used as the short-wavelength side transmission filter 11, the transmittance at the point where the filter 11 intersects the filter 12 at an incident angle of 0 degree is set high in consideration of the manufacturing error and the manufacturing error of the filter 12. It is desirable to keep. Further, as described above, since the rate of change of the wavelength shift increases as the inclination angle of the filter increases,
When the change rate of the filter rotation angle and the wavelength shift accompanying the operation of the adjustment knob is substantially constant, adjustment during observation is easy. Further, taking into account the characteristics of the filter 12, the amount of transmitted light in the crossed area is an element that receives observation light (eye, CCD, etc.).
Is desirably set so as to linearly change according to the sensitivity. In addition, it is desirable that the filter 11 can be selected in order to cope with autofluorescence having different excitation characteristics and fluorescence wavelengths of various portions and fluorescence requiring a marker.

As described above, the medical endoscope of the present invention has the following features in addition to the features described in the claims. (1) The transmittance at the point where the filter 11 intersects with the filter 12 at an incident angle of 0 degree is determined by the filter 11
The medical endoscope according to any one of claims 1 to 3, wherein the medical endoscope can be adjusted in a lower direction by tilting.

(2) The inclination angle of the filter 11 is 0 to 3
The medical endoscope according to any one of claims 1 to 3, or (1), which can change within a range of 0 degrees.

(3) The filter according to any one of (1) to (3) or (3), wherein an adjustment amount of a knob for rotating the filter 11 and a change in transmittance due to the rotation of the filter 11 are substantially proportional. The medical endoscope according to 1) or (2).

(4) The apparatus according to any one of claims 1 to 3, wherein an adjustment amount of a knob for rotating the filter 11 is substantially proportional to an amount of transmitted light in an area where the filters 11 and 12 intersect. Either or the above (1) or (2)
4. The medical endoscope according to claim 1.

[0024]

As described above, according to the present invention, it is possible to provide a medical endoscope which always enables good fluorescence observation through an eye or an imaging device such as a CCD.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an endoscope according to the present invention.

FIG. 2 is a graph showing a filter transmittance curve and light intensity with respect to wavelength.

FIG. 3 is a graph showing a change in transmittance characteristic with respect to a change in a rotation angle of a short wavelength transmission filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Objective lens 3 Eyepiece 4 Rod lens device (image guide) 5 Long wavelength transmission filter (5) Transmittance curve of filter 5 6 Observation area 7 Light guide fiber bundle 8 Light source 9 Lamp 10 Lens system 11 Short wavelength side Transmission filter (11) Transmittance curve of filter 11 12 axis 13 intersection 14 background light 15 fluorescent image

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Andreas Mutskner 22045 Hamburg Kiyun Schuttraße 61 Olympus Winter und Ive

Claims (3)

[Claims] 1. Partially fluorescent region 6 to be observed
Illumination devices 7 and 8 having a short wavelength transmission filter 11 for irradiating light, and observation devices 2, 3 and 4 having a long wavelength transmission filter 5, and one of the two filters 5 and 11. Is formed as an interference filter, and is configured such that, in a fluorescence wavelength region (blue) shorter than the red fluorescence wavelength band, the transmittances of the two filters intersect at a value smaller than the maximum transmittance of each filter. In the medical endoscope, the interference filter is configured to be adjustable in angle with respect to a traveling direction of light. 2. The interference filter 11 includes: a lighting device 7;
The medical endoscope according to claim 1, wherein the medical endoscope is provided inside the medical endoscope. 3. The lighting device according to claim 2, wherein the lighting devices have a light source connected by a light guide cable, and the interference filter is provided in the light source. The medical endoscope according to claim 1.