JPH0143687Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an endoscope optical system, and more particularly to an endoscope optical system that prevents deterioration of the plastic elements in an optical system consisting of a combination of a glass element and a plastic element.

BACKGROUND ART Conventionally, endoscopes equipped with optical fiber bundles and the like have been inserted into the human body and used as a means for transmitting images or light for the purpose of diagnosis and treatment.

After use, a doctor or an assistant washes the endoscope with water and disinfects it with alcohol or the like, and then stores the endoscope in a sterilization case and sterilizes it by irradiating it with ultraviolet rays.

In recent years, plastic elements such as acryl have been used as endoscope optical system elements, and a phenomenon has occurred in which these plastic elements deteriorate due to the ultraviolet irradiation and the like.

That is, the wavelength range of the ultraviolet rays used in the sterilization case, that is, the wavelength range that exerts the sterilization effect, is the first wavelength range.
As shown in the figure, a relatively narrow wavelength range with the center wavelength λ = 253.7 nm is the most desirable for the bactericidal effect of ultraviolet irradiation.

As shown in Figure 1, this means that the wavelength λ=
If the sterilization effect of 253.7nm is 1, the wavelength λ=
At wavelengths below 200 nm and above 310 nm, the bactericidal effect decreases to less than 1/100, and the visible light range wavelength λ =
It is clear that at wavelengths above 400 nm, the bactericidal effect actually decreases to less than 1/1000.

Furthermore, the spectral transmission characteristics of the plastic element are as shown in FIG.
Transmits a wide range from around 250nm to infrared wavelength λ = around 2200nm.

Here, when the plastic element is irradiated with the ultraviolet rays, it changes color to brown and cracks, resulting in phenomena that are unfavorable in terms of optical performance.

As an example, FIG. 3 shows the spectral transmission characteristics of a plastic plate (1 mm thick) after being continuously irradiated with the ultraviolet rays for 120 hours.

According to the spectral transmission characteristics shown in Figure 3, the short wavelength side of the visible range is absorbed by plastic, resulting in an unnatural color characteristic with a low color temperature, which is difficult to diagnose with an endoscope due to minute color changes. This discoloration phenomenon is highly undesirable.

On the other hand, the cracking phenomenon disturbs the uniform light beam, significantly deteriorating the imaging performance especially in the imaging system, which is extremely undesirable for endoscopes that require accurate diagnosis.

One way to prevent deterioration such as discoloration and cracking due to ultraviolet rays is to attach an ultraviolet reflecting (or absorbing) film to the plastic element itself. However, this reflective (or absorbing) film deposition method generally requires very high temperatures (over 300°C).
Since the process is carried out under such conditions, the plastic itself melts and it is extremely difficult to attach the film directly to the plastic element.

On the other hand, there is a method of attaching the film at a low temperature at which the plastic does not melt, but this method is not practical because the film has low strength and lacks durability.

In view of these points, in the present invention, in an endoscope optical system consisting of a combination of a glass element and a plastic element, an ultraviolet reflecting (or absorbing) film is attached to the glass element, and this element is applied to the plastic element. An object of the present invention is to provide an endoscope optical system in which deterioration of the plastic is prevented by arranging the plastic to block ultraviolet rays.

Hereinafter, the present invention will be explained based on the embodiments shown in the accompanying drawings.

Figure 4 is an example of a spectral transmission characteristic diagram of a thin film that reflects ultraviolet rays used in the optical system of the present invention. It effectively transmits the information.

Figures 5 and 6 are main part configuration diagrams of the optical system of the present invention using the optical system to which the thin film C having the spectral transmission characteristics shown in Figure 4 is attached, and the same reference numerals indicate the same agents. , the optical elements shown with diagonal lines are plastic elements.

FIG. 5A shows an embodiment of the objective optical system at the end of the endoscope, in which the lens 3, which is an element of the objective lens for forming an image on the end surface of the image guide 1, is used as a plastic lens, and the objective lens 4 on the subject side is used as a plastic lens. The thin film C is attached to the image forming surface side of the lens 3 to protect the lens 3 from ultraviolet rays.

FIG. 5A shows an example in which the lens 4 is used as a cover glass, and FIG. 5C shows an example in which the prism 6 for changing the optical path is used as a plastic prism in a side-viewing endoscope objective lens system. .

FIG. 5D shows an embodiment of the endoscope tip illumination optical system, in which a plastic lens is used as the lens 11 for diverging the light beam from the light guide 10, and the thin film C is adhered to the cover glass 5. is protected from UV rays.

FIG. 5E shows an example in which the prism 13 for changing the optical path of the side viewing endoscope illumination optical system is used as a plastic prism, and FIG. 5F shows an example of the light guide 10 using a plastic fiber. The thin film C is attached to protect the light guide 10 from ultraviolet rays.

6A and 6B show an embodiment of the endoscope eyepiece optical system, in which plastic lenses are used as parts of the eyepieces 8 and 7 for observing images from the image guide 1, and the lenses 8 and 7 on the observation side are made of plastic lenses. An example is shown in which the thin film C is attached to a parallel plane glass 9 to prevent ultraviolet rays from the observation side.

In any of the embodiments of FIGS. 5 and 6,
The present invention is particularly effective when the plastic element is located relatively in front of the optical system, that is, in the direction of incidence of ultraviolet rays. In the embodiments of FIGS. 5 and 6, the plastic element consists of a single plastic element, but a plurality of plastic elements may be used.

This effect may be achieved by placing an ultraviolet cut filter in the optical system. For example, it is possible to replace the cover glass 5 in FIG. 5 and the parallel plane glass 9 in FIG. 6 with an ultraviolet cut filter.

It goes without saying that the present invention is effective not only for the ultraviolet rays of the sterilizing case but also for ultraviolet rays with other spectral characteristics that are harmful to plastic elements.

As explained above, according to the optical system of the present invention,
It is possible to prevent deterioration of the optical system including the plastic element even when exposed to ultraviolet rays after using the endoscope, and to effectively transmit visible light with an ultraviolet reflection or absorption film, the color characteristics of the line have been taken into account. does not have any adverse effect on the endoscope observation optical system or imaging system.

In addition, by preventing the deterioration of the plastic elements, the endoscope optical system can be easily made of plastic and can be provided at low cost, making it possible to provide an endoscope optical system that is more versatile than ever before.

[Brief explanation of drawings]

Figure 1 is a diagram showing the ratio of sterilizing effect to wavelength, Figure 2 is a diagram showing the spectral transmission characteristics of acrylic plastic, Figure 3 is a diagram showing the spectral transmission characteristics of the plastic after deterioration, and Figure 4 is a diagram showing the spectral transmission characteristics of the plastic. A diagram showing the spectral transmission characteristics of the ultraviolet reflection film used in the invention, and FIGS. 5 and 6 also show main part configuration diagrams showing an embodiment of the invention, respectively. 1... Image guide, 2 and 3... Objective lens, 4... Concave objective lens, 5... Cover glass, 6 and 13... Optical path conversion prism, 7 and 8... Eyepiece lens, 9... Parallel plane glass, 1
0...Light guide, 11...Concave lens, 14...
...Concave lens, C...UV reflective film.

Claims (1)

[Scope of utility model registration request] In an endoscope optical system consisting of a combination of a glass element and a plastic element, a glass element is arranged at the outermost side of the endoscope optical system, and a thin film that reflects or absorbs ultraviolet rays is provided on the light transmission surface of the glass element. An endoscope optical system characterized by being attached.