JPS5887523A - Image forming optical apparatus - Google Patents

Abstract

PURPOSE:To eliminate uneven illumination of an image forming optical system such as an endoscope, by providing a brightness distribution controller of illumination light irradiated to an object surface of a illuminating device, by an output of a detecting device for detecting a brightness distribution of the object surface by an output signal of a device for photodetecting the light from the object surface to be illuminated. CONSTITUTION:When uneven brightness has been generated on a surface to be irradiated 3, information of the uneven brightness which has formed an image on a photodetector 17 from an image guide is inputted to an electric signal processor 11 from a lead wire 18, in which it is processed, and thereafter, a control signal is sent to a driving device 10. Subsequently, a base 8 is turned, the position of a light spot P from a light source lamp 6 is varied on an incident end face of a light guide 5, and light distribution of light emitted from an illuminating optical system 2 is varied, therefore, when the base 8 is turned in the direction for eliminating the uneven brightness, the uneven brightness of an endoscope is eliminated, and a satisfactory image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging optical device such as an endoscope that eliminates uneven illumination.

For example, as shown in FIG. 1, a conventional endoscope uses an illumination optical system 2 of an endoscope distal end 1 when observing the inside of the body.
- When the distance to the object plane 3 did not change much depending on the viewing direction, a field of view that was almost uniformly illuminated could be obtained. However, as shown in Figure 2, when looking at a part shaped like the intestinal wall, the distance to the object plane 3 varies significantly depending on the direction within the field of view, so there are particularly bright and dark areas in the field of view. This bright area is not much of a problem when observing with the naked eye, but when attaching a camera to the observation optical system 4 of the endoscope and taking photographs, the exposure latitude range of the film is smaller than that of the human eye. The problem was that because the area was so narrow, the image appeared pure white, making it impossible to record. Furthermore, an image of the subject is formed in the observation optical system 4 of the endoscope using a television camera or an electronic camera (lens, etc.), and the light intensity distribution of the image is converted into a signal and subjected to appropriate processing. When taking pictures with a camera attached to an endoscope (a camera that obtains information), television cameras and electronic cameras have narrower exposure latitude ranges than film cameras, so they can quickly cause halation, making observation impossible. There was a problem with putting it away. The same problem also occurs in endoscopes that use a solid-state imaging device such as a COD instead of an image guide.

In view of the above-mentioned problems, the present invention aims to provide an imaging optical device such as an endoscope that prevents uneven illumination. To explain this based on an example, 5 is a light guide whose output end is placed behind the illumination optical system 2, 6 is a light source lamp, and 7 is a light source lamp that focuses the light from the light source lamp 6 onto the input end of the light guide 5. 8 is the light source Lanzoro and the condenser lens 7
are identified together and can be rotated in the vertical direction of the drawing, 9 is a support shaft to which the stand 8 is pivoted and can be rotated in the vertical direction of the drawing, and 10 is a support shaft 9 is a driving device that pivots and moves the table 8 in the vertical and vertical directions of the drawing; 11 is an electric signal processing device that controls the driving device 10;
An image guy 12 has an entrance end placed behind the observation optical system 4. An image guy 13 has an entrance end placed behind the output end of the image guide 12 and transfers the image of the output end to the film surface 14 of the camera.
an eyepiece lens 15 for forming an image on the film surface 14;
Reference numeral 16 denotes a refined imaging lens which images the friendly light split by the beam splitter 15 onto the image receiving element 17. Reference numeral 18 denotes a lead wire for inputting the output of the image receiving element 17 to the electrical signal processing device. .

It should be noted that the light guide 5 does not have to have the positions of the incident end and the output end of each fine line correspond perfectly like an image guide, but roughly correspond to each other like a normal light guide. (Such a light guide is called a TLG). For example, as shown in FIG. 4, several fine lines may correspond to each other as a group. In this case, the fiber clusters l and 1', 2 and 2', 3 and 3', and 4 and 4' correspond to each other, but some of the fibers included in cluster 1 correspond to each other. 77'f' whose relative position is 1'
It is not necessary to match the relative positions of the two. Also, lump 1
Some of the fibers contained inside may penetrate ID 2', 3', 4' to some extent. Alternatively, as shown in FIG. 5, several light guides may be bundled together. In this case, 1, 2.・・・・・・
, 9 are each one light guide. Further, the image receiving element 17 may be of any type as long as it can detect uneven brightness of the visual field image of the endoscope. For example, as shown in FIG. 6, the endoscope field of view 20 may be divided into four parts using four SPDs (silicon photodiodes) 19 to measure the brightness, or as shown in FIG. Alternatively, a solid-state image sensor 21 such as a COD may be used instead. Further, the image receiving element 17 may be provided inside the camera instead of inside the endoscope. What is important is to provide an element that divides the field of view 20 into two or more parts and allows the brightness of each part to be measured independently. Further, the image at the output end of the image guide 12 does not need to be completely focused on the image receiving element 17. This is because even if the image is somewhat blurred, unevenness in brightness can be detected.

Since the imaging optical device according to the present invention is constructed as described above, if a situation occurs in which uneven brightness occurs, for example as shown in FIG. An image is formed on the image, and information on the uneven brightness is inputted to the electrical signal processing device 11 via the lead wire 1.8.

The electrical signal processing device 11 analyzes this information and
0, the drive device IO rotates the stand 8, and as a result, the position of the condensing point P of the light emitted from the light source lamp 6 by the condensing lens 7 is on the incident end surface of the light guide 50. The changing position of the focal point P is the light guide 5
If the incident end face of , and a good image can be obtained. Note that the table 8 may be moved manually without using the drive device 10.

Next, the principle by which the light distribution of light emitted from the illumination optical system 2 changes when the position of the light condensing point P changes on the incident end surface of the light guide 5 will be described in detail. As shown in FIG. 8, the inside of the light guide 5 is divided into three parts A, B, and C, each of which has a corresponding input end and an output end. Generally, among the light emitted from a light guide, the light parallel to the axis of the light guide has the highest intensity, and is called the chief ray. These three parts A, B, C! The principal ray emitted from the is refracted by the illumination optical system (in this case, a concave lens) 2 and becomes a ray a.
, b, and c, and since the rays a, b, and c have different traveling directions, they illuminate different parts of the endoscopic field of view. As shown in Fig. 8, if the condensing point P is on the incident end face of part B, the light ray becomes strong and the center of the field of view becomes bright1.If the converging point P comes to the incident end face of part A, the light ray a becomes strong. The upper part of the field of vision becomes cloudy.

When the condensing point P comes to the incident end face of the portion C, the light ray C becomes stronger and the lower part of the field of view becomes brighter. Thus, the light distribution of the light emitted from the illumination optical system 2 changes. In this case, since the condensing point P has a spread, even if the condensing point P is on the incident end surface of the portion A, it is possible to enter the light into the portions B and c.

Incidentally, if the electrical signal processing device 11 knows the correspondence between the incident end and the outgoing end of the light guide 5, it is sufficient to send a signal to the drive device 1o to move the table 8 in a direction that reduces uneven brightness. If you do not know the correspondence relationship (or even if you know it), try moving the platform 8 a little and calculate whether the uneven brightness has decreased or increased as a result, and if the uneven brightness has decreased, then Continue to move the platform 8 in the direction,
On the other hand, if the ratio is increasing, it is sufficient to send a signal to move the platform 8 in the opposite direction.

Next, to show another example of the illumination image 1, FIG.
An example of changing the position of is shown. FIG. 10 shows an example in which the position of the condensing point P is changed by moving only the condensing lens 7 parallel to the incident end surface of the light guy P5. In addition, the position of the condensing point P may be changed by fixing the condensing lens 7 and moving the light sources Ran and Zoro in parallel, or by concentrating light with the light source Ran and Zoro and moving the lens 7 independently. . FIG. 11 shows an example in which a thick glass plate 22 is arranged between the condenser lens 7 and the incident end surface of the light guide 5, and the condensing point P is moved by tilting the glass plate 22 with respect to the optical axis 0. It shows. In this case, if the glass plate 22 is made of heat ray absorbing glass, the effect of suppressing the temperature rise at the incident end face of the light guide 5 can also be obtained. FIG. 12 shows an example in which the light source 6 and the condensing lens 7 are fixed and the incident end of the light guide 5 is moved. FIG. 13 shows an example using a light source 23 with a large bright spot (filament), which forms an image uniformly on the incident end face of the light guy P5, and makes the image of the bright spot on the incident end face. The light distribution is changed by partially cutting the light with a shutter 24 inserted between the light and the condenser lens 7. In this case, the shutter 24 may be inserted between the light source lamp 23 and the condenser lens 7, or two or more shutters 24 may be used.

, FIG. 14 shows another example of a light guide, in which the fiber in the center at the output end extends to a part of the periphery at the input end. This is the first
When used as shown in FIG. 5, by moving the position of the condensing point P, it is possible to brighten the center of the field of view or brighten the periphery.

FIG. 16 shows an example of another illumination device using the light guide 25. By moving the condensing lens 7 along the optical axis, the condensing point on the incident end surface of the light guide 250 is blurred and made thicker. The light distribution is changed by condensing the light or condensing it to make it smaller.

FIG. 17 shows yet another example of a light guide, in which this light guide 26 has a fiber in the center at the output end,
The fibers are located at the periphery at the input end, and the fibers located at the periphery at the output end are located at the center at the input end. If this is used as shown in FIG. When you are near the area, the center of your field of vision will be brightly illuminated.

Note that the condenser lens 7 is not limited to the direction perpendicular to the optical axis O;
It may be moved parallel to the optical axis 0.

That is, by moving parallel to the optical axis O and blurring the condensing point P on the entrance end face of the A guide 26, both the center and the periphery of the entrance end face will be illuminated, so that the field of view will be uniformly illuminated. I can do it.

FIG. 19 shows an example of another illumination device using a light guide 27 with a bifurcated entrance end, in which two light sources and two condensing lenses 7 are provided corresponding to the bifurcated entrance end. is arranged. In this case, the uneven brightness is corrected by automatically adjusting the light amount ratio of the two light source lamps 6. In addition, light guide 2
The incident end of 7 may be divided into three or more parts, and corresponding light source lamps 6 and condensing lenses 7 may be provided for each part.

Further, to change the brightness of the light source run, for example, the power supply current may be changed, the shutter 24 may be used, or a filter (not shown) may be used in place of the shutter 24. .

FIG. 20 shows an example of another lighting device using two Ichimei systems that illuminate different directions, and it is possible to eliminate unevenness in brightness by adjusting the light quantity ratio of the two light sources Lanzoro. FIG. 21 shows an example in which the light guide 27 shown in FIG. 19 is used with its incident end and output end reversed, and shows the positions of the light W Lanzoro, the condensing lens 7, and the incident end of the light guide 27. By changing the relationship and changing the position of the condensing point P on the incident end face of the light guide 27, it is possible to eliminate unevenness in brightness within the field of view. FIG. 22 shows an example in which a normal light guide 5 is used, and the light source lamp 6 and condensing lens 7 rotate approximately around the incident end of the light guide 5. The larger the angle α between the axis t and the axis m of the condensing lens 7, the larger the emission angle ω of the light from the output end of the light guide 5. Therefore, by changing the angle α according to the uneven brightness of the screen, By adjusting the light distribution, you can get a screen with even brightness.

Next, another embodiment of the imaging optical device according to the present invention will be described. FIG. 23 shows an example in which a television camera 28 is attached to an endoscope. In this case, the image receiving element 1 in FIG.
7 is not necessary, and the signal from the television camera 28 is input to the image processing device 29.
Automatic light control becomes possible by detecting unevenness in brightness and inputting a signal to the drive device 8 to move the stand 8 so as to eliminate unevenness in brightness. FIG. 24 shows an example of an endoscope using a solid-state image sensor 30 such as a COD, in which an image signal from the solid-state image sensor 30 is sent to an image processing device 29 to detect unevenness in brightness. A drive signal is sent from the image processing device 29 to the drive device 8 to remove unevenness in brightness within the field of view. This basic idea is the same as the embodiments shown in FIGS. 3 and 23.

Figure 25 shows an example of a combination of force, camera and stroke, where 3°1 is the camera lens, 32 is the film surface, and 33
34 is an imaging lens, 35 is an image receiving element, 36 is an electric signal processing device, 37 is a strobe lighting device, and 38 is two strobes facing different directions,
The electrical signal processing device 36 detects unevenness in brightness,
A signal for adjusting the light intensity ratio of the two strobes 38 is output from the electric signal processing device 36 to the strobe lighting device 37. That is, by individually changing the light emission times of the two strobe lights 380, uneven brightness can be removed. Also, unlike this embodiment, as shown in FIG. 24, the brightness is measured by two light receiving elements 39 placed near the two straws 138 facing different directions, and these output signals are converted into electrical signals. The light may be sent to the processing device 36 to control the strobe lighting device 37, and by changing the At1 time of the two strobes 38, unevenness in brightness may be removed. Alternatively, as shown in FIG. 27, two light receiving elements 39 may be mounted so as to face the film surface 32, and the uneven brightness may be detected by measuring the reflected light from the film surface 32. Further, FIG. 28 shows an image receiving lens 40 facing the subject surface and the image receiving lens 40.
An example is shown in which the brightness distribution on the object surface is detected by using the image receiving element 35 placed at the imaging position. In each of the embodiments shown in FIGS. 25, 26, 27, and 28, if the film surface 32 is replaced with a solid-state image pickup device such as an OCD or a vidicon, an electronic camera, It can also be applied to TV cameras, etc.

Figure 29 shows the light receiving element 3 for detecting unevenness in brightness.
9 is provided at the distal end portion 1 of the endoscope, and the output signal of the light receiving element 39 is inputted to the electrical signal processing device 11, and the subsequent city control is performed in accordance with the embodiment shown in FIG. The same is done. FIG. 30 shows an example in which the camera shown in FIG. 27 is attached to an endoscope, in which a plurality of light receiving elements 39 arranged facing the film surface 32 detect unevenness in the brightness of the image. The output signal of the light receiving element 39 enters the electric signal processing device 1t36, the electric signal processing device 36 sends a signal to the light source dimmer 40, and the light source dimmer 40 outputs the signal to the light source device 41.
By controlling the brightness, unevenness in brightness can be removed. The structure of the light source device 41 in this case is as follows:
A device using a plurality of light source lamps as shown in FIG. 20 is suitable because the response is quick. The uneven brightness is removed by adjusting the light amount of each of the plurality of light source lamps. Note that when the film is not exposed, instead of receiving the reflected light from the film surface 3'2, the reflected light from the shutter film 42 may be received to detect unevenness in brightness.

As mentioned above, the imaging optics according to the invention has the very important advantage of less uneven brightness within the field of view.

Note that the present invention is not limited to endoscopes, cameras with strobes, etc., but also includes rigid endoscopes, electronic cameras with strobes, and lighting devices.
It can be applied to general optical equipment with an illumination device, such as a binocular stereomicroscope with a d-equipment and a television camera. Also, depending on the purpose of use, it is possible to emphasize uneven brightness or to always illuminate only a specific area, but in that case, the electrical signal processing device can be modified in terms of hardware or software. .

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing illumination conditions by a conventional endoscope, FIG. 3 is a cross-sectional view showing an embodiment of an imaging optical device according to the present invention, and FIGS. 4 and 5, respectively. A perspective view showing an example of a light guide used in the above embodiment, FIGS. 6 and 7 are front views showing an example of an image receiving element used in the above embodiment, and FIG. 8 is a lighting device of the above embodiment. 9 to 13 are diagrams each showing examples of other lighting devices, and FIG. 12 is a perspective view showing examples of other light guides. FIG. 16 is a diagram showing an example of another illumination device using the other light guide described above, FIG. 17 is a diagram showing an example of still another light guide, and FIG. A diagram showing an example of a lighting device, FIGS. 19 to 22 are diagrams showing examples of other lighting devices, respectively.
FIGS. 23 to 30 are views showing other embodiments of the imaging optical device according to the present invention. 1... Endoscope tip, 2... Illumination optical system, 3...
Object plane, 4... Observation optical system, 5... Light guide,
6... Light source lamp, 7... Condensing lens, 8... Stand, 9... Support shaft, lO... Drive device, 11... Electric signal processing device, 12... Image guide , 13...
Contact lens, 14... Film surface, 15... Beam splitter 116... Imaging lens, 17... Image receiving element, 18... Lead wire. 115 Figure 116 Figure 17 Figure 119 Figure 24 7 6 (,・ 2nd Seal Figure 23 Figure 9 Figure 24 Figure 9 10 8 6 Procedural amendment (method) September 10, 1981 1, Patent application for indication of the case Publication No. 56-185700 - No. λ Name of the invention Person making the amendment to the imaging optical device Relationship to the case Patent applicant 5 Date of amendment order August 31, 1980 6 Drawings of the specification to be amended 7. Contents of the amendment (11 Specification, page 16, line 17, "Fig. 12-1
Figures 1 and 4” is corrected.

Claims (1)

[Claims] An imaging optical device comprising an illumination device that illuminates an object surface and an observation/photographing device that observes and photographs the illuminated object surface, the light receiving device receiving light from the illuminated object surface and the light receiving device. a detection device that detects a brightness distribution on an object surface based on an output signal of the device; and a detection device that controls a brightness distribution of illumination light irradiated onto the object from the illumination device based on the output of the detection device. An imaging optical device comprising a control device.