Analysis of water leakage of medical optical fiber endoscope

Time：2020-07-26 00:13 Click：/Second

Medical optical fiber endoscopes have been widely used in hospital inspections, treatments, operations, and scientific research. Water leakage is one of the most common failures of medical fiber endoscopes, which can affect observation at a slight degree, and cause fiber endoscopes in severe cases. scrapped.

To check whether the machine is leaking, the operator must first understand the structure and function of the fiber endoscope (take the OES series fiber endoscope from Japan as an example). The fiber endoscope includes eyepieces, light guide joints, and operation Department and Insertion Department.

　　Eyepiece

　　 is used to observe images and connect camera and photography equipment.

　　 Light guide connector

　　 is used for the supply of light guide, water and steam and the connection of cold light source, suction device and auxiliary equipment.

　　Operation Department

　　 is used to adjust the direction of the image to be observed, the position of the treatment, and adjust the water, air, and suction volume.

　　 insert part

　　 is used to insert into various organs in the body. Its structure is complex, mainly including objective lens, image guide beam, light guide beam, tip, curved tube, snake tube, curved rubber, water pipe and suction pipe.

The basic structure of optical fiber endoscopes is as described above, but due to their different applications, various types of endoscopes have been produced, including upper gastrointestinal fiber endoscopes (gastroscopes), colonoscopes, enteroscopy, ten Diodenoscopy, bronchoscopy, choledochoscopy, etc. In order to facilitate the treatment, it is divided into various models, and the structure is different.

　　The following introduces the phenomena that occur when the optical fiber endoscope leaks and the reasons for these phenomena

　　

1. Blurred image

　　 Once the endoscope leaks, the image will be unclear at first. But it is not certain that the image blur is caused by water leakage. It may be that the protective glass at the tip is dirty or frayed, or the objective lens has oily fog, or there is a problem with the eyepiece itself, or it may be between the objective lens and the image guide beam. The relative position between the eyepiece and the image guide beam moves. After eliminating these problems, it can be determined that the machine is leaking. The reason for the blurring of the image is very simple, because the water adheres to the end surface of the optical part after the water enters.

　　

2. There is a crack in the guide beam, referred to as a crack (shaped like a pattern on the back of a turtle)

　　 This phenomenon often takes place for a period of time after the machine is leaking, and only appears when the moisture starts to dry. To find out the reason for this phenomenon, we must first understand the composition of fiber endoscope imaging. The imaging part of the fiber endoscope is composed of an objective lens, a guiding image bundle, and an eyepiece. The object is imaged on the end surface of the guiding image bundle through the objective lens, and then transmitted to the other end of the image bundle through the guiding image bundle, and then magnified by the eyepiece. Like what we see. The image-guided bundle is composed of many thin hair-guide fibers arranged in a certain order. Each light-guide fiber conducts an image point. The conduction of the image point is caused by total reflection inside the fiber. After the fiber endoscope leaks water , Moisture will destroy the reflective film of the light guide fiber. The image point will not be totally reflected by the light guide fiber, but will be partially refracted, which will attenuate the brightness of the light, and then a part of the image will appear shadow. After the shadow is enlarged through the eyepiece, look It looks like a turtle pattern.

　　

3. Rainbow

　　 Sometimes the machine will appear like a rainbow in the sky after being flooded. This phenomenon also occurs after the water leaks and is left to dry for a period of time. As mentioned above, the image guide beam is composed of many light guide beams arranged in a certain order. Its arrangement is shown in Figure 2.

figure 2

The operator looks like a circular image, but in fact, each light guide must be arranged in an equilateral triangle to prevent the image from changing during the transmission process. The operator will know it after careful observation, especially after camera and photographic magnification. The picture of will see more clearly. When we study the whole image bundle in three dimensions, there are countless prisms. Natural light passes through the prism and is divided into monochromatic light of various colors. The principle of rainbow appearance in the fiber endoscope is the same as that of the prism.

　　

4. Water drops appear

　　 The operator will see in the field of vision that there is a transparent substance in the middle of the black edge, and sometimes the position changes with the shaking of the machine. The reason for the formation should be too much water, and the water enters the entire machine.

　

5. No abnormalities can be observed outside the body, and a little bit of pitting appears once inside the body

(It is different from the breakage of the guide image bundle fiber). This is because the water leakage is not obvious, the water entering the machine is not too much, and the temperature and humidity difference between the body and the body are caused. This is the same as what we encounter in daily life. The difference between indoor and outdoor temperature and humidity makes the window glass adhere to moisture. The main phenomena and reasons for the leakage of fiber endoscopes are probably the above five aspects. There are also red light from the light guide, and the bending angle of the bending tube is not enough, and the insertion tube snaking may also be due to water leakage. The leakage of fiber endoscope does not necessarily have only one phenomenon, and sometimes multiple phenomena exist at the same time. Once the fiber endoscope leaks, it must be stopped and sent to the repair center as soon as possible. The following describes the method of testing whether the fiber endoscope is leaking.

　　 Endoscope manufacturers generally provide endoscope leak test equipment. For example, OLYMPUS OES series endoscopes have MB-155 leak tester. The method of use has been introduced in the manual of the standard equipment. Its principle is to use a cold light source air pump to pump air to various parts of the endoscope, then put the endoscope into water and add water to the place where the endoscope can be submerged, and observe whether there are bubbles in each part of the endoscope. (This method is necessary in our daily maintenance of fiber endoscopes, and it does not have to be used after water leakage). The specific operation is as follows

　　(1) First, prepare a basin that can be put into the endoscope when it is naturally bent, and add water to at least submerge the endoscope.

　　(2) Remove the water vapor, suction button and clamp valve on the endoscope. Connect the endoscope, cold light source and leak tester, turn on the cold light source power switch and adjust the air pump to the maximum.

　　(3) Put the endoscope flat in the water, and use a syringe to inject water into the water trachea and suction tube, and adjust the bending angle while observing whether there are any bubbles overflowing.

　　 If there are bubbles overflowing, the location of the leak should be near the pipe where the bubbles appear. Fiber endoscopes are most likely to leak water in the bent rubber, water and gas pipes and clamp pipes. Endoscopes are expensive. After a water leak occurs, maintenance costs are high, and work is delayed. Except for the replacement of main parts, the possibility of complete repair is extremely rare. Therefore, the operator must operate as required, and do daily storage and maintenance work to prevent water leakage.

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Analysis of water leakage of medical optical fiber endoscope

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