JPH0541382Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a photodetector in which fine dust does not adhere to the surface of the photodetecting element.

[Conventional technology]

There are various materials and structures for the light absorber of a thermal conversion type photodetector. With the exception of some high-output photodetectors, the surface structure of light absorbers with high light absorption efficiency, that is, high efficiency in converting light energy into thermal energy, is extremely fine with a wavelength on the same order of magnitude or less. It has an uneven structure.

The structure of gold and black, which is one of the most excellent light absorbers, is a typical example. In this method, ultrafine gold particles in a semi-solidified state are deposited on the surface of an absorber substrate by introducing an inert gas during the gold vapor deposition process.

Such a fine structure is extremely susceptible to the adhesion of fine dust, and it is impossible to remove the fine dust once adhered by cleaning, blowing off, or the like.

Such adhesion and accumulation of fine dust on the surface of the light absorber causes deterioration in light absorption efficiency, and becomes a factor in deterioration over time of detection sensitivity as a photodetector. Therefore, in photodetectors such as standard photodetectors where minute changes in detection sensitivity are a problem, prevention of fine dust from adhering to the light absorber is an important problem in use.

The most effective measure to prevent fine dust from adhering to the light absorber is to provide a light-transmissive window 3 on the front surface of the light absorber 2 of the photodetector element 1, as shown in FIG. However, the materials that can be used for window 3 are:
It produces a reflection of at least a few percent to more than 50%. Therefore, the use of the window 3 eliminates the high light absorption efficiency characteristic of the ultrafine structure light absorber 2.

In addition, in order to prevent reflection from the window 3, an anti-reflection film may be provided on both sides of the window 3, but an anti-reflection film configured to keep the reflection low enough to match the performance of the light absorber 2. The wavelength dependence is large;
Substantially usable wavelengths are limited to a narrow range in the immediate vicinity of the specific design wavelength.

Normally, in a photodetector where particle adhesion is undesirable, the optical input part is always covered except when in use, but the same detector can be used to measure spatial beams and connect the plug. When performing both optical fiber system measurements using
Even in optical fiber measurements, when the optical input part must be replaced, such as when used for multiple connectors of different types, and for photodetectors that are connected to optical fiber connectors, countermeasures should be taken when not in use. alone is not sufficient. Below, Fig. 5 a, b, Fig. 6 a, b,
The reason will be specifically explained using FIGS. 7a, b and 8a, b, and c.

FIGS. 5a and 5b and 6a and 6b are diagrams for explaining the process of fine dust adhering to the surface of the light absorber when replacing the input section.

In these figures, the same reference numerals as in FIG. 4 indicate the same parts, 4 is a jacket, 5 is a heat insulating material, 6 is an optical input section, 7 is a receptacle for an optical fiber plug attached to the optical input section 6, 7a is a hole of the receptacle 7, and 7b is a small hole. Figure 5a
When the light input section 6 is removed from the state shown in FIG. 5B as shown in FIG. is lowered and an air flow is generated, causing the movement of fine dust inside the space and a vortex, a part of which adheres to the surface of the light absorber 2.
Further, as the internal pressure decreases, air also flows in from the outside, so some of the fine dust carried by this also reaches the surface of the light absorber 2.

Furthermore, when the optical input section 6 is attached as shown in FIGS. 6a and 6b, the flow shown in FIG. 6a is generated, and as the internal pressure increases, the flow shown in FIG. A part of the internal air flows out from the hole 7a, and in this process, fine dust adheres to the surface of the light absorber 2.

Furthermore, FIGS. 7a, b, and 8a, b, and c are diagrams for explaining the process of attaching and detaching the ferrule 8 with the optical input section 6 having the receptacle 7 attached.

That is, as shown in FIG. 7a, the ferrule 8
As the tip of the receptacle 7 enters, the volume of the space formed by the ferrule 8 and the hole 7a of the receptacle 7 decreases. Furthermore, since the distance between the outer wall of the ferrule 8 and the hole 7a is extremely small (approximately 2 μm) in order to maintain the accuracy of the center position of the optical fiber, when the insertion speed of the ferrule 8 is high, the distance shown in FIG. As shown, air blows out toward the surface of the light absorber 2 through the small holes 7b, causing fine dust to adhere thereto.

Furthermore, when the ferrule 8 is pulled out from the inserted state as shown in FIG. 8a, as shown in FIG.
As shown in FIG. c, external air is absorbed into the receptacle 7 and causes fine dust to adhere to the light absorber 2.

[Problem that the invention attempts to solve]

In the conventional photodetector as described above, the optical input section 6
When replacing the light absorber 2 and attaching/detaching the connector,
There was a problem that the detection sensitivity deteriorated due to fine dust adhering to the surface of the sensor.

This invention has been made in order to solve such problems, and has as its object to provide a photodetector which can effectively reduce deterioration over time of detection sensitivity caused by the adhesion of fine particles.

[Means for solving problems]

The photodetector according to this invention has a shutter part that protects the surface of the photodetecting element, and a light input part that is attached to the connection part when the shutter part is in an open state that does not protect the surface of the photodetecting element. engages with the joint,
Alternatively, the connecting portion is provided with an attachment/detachment restriction mechanism including a blocking portion that prevents the optical input portion from being attached to or removed from the connecting portion.

[Effect]

In this invention, when the shutter part of the attachment/detachment restriction mechanism is in the open state where the surface of the photodetector element is not protected, the engagement part of the attached light input part is engaged by the blocking part of the attachment/detachment restriction mechanism. and its removal is prevented. Furthermore, attachment of the optical input section is also prevented by the blocking section.

〔Example〕

Figures 1a and 1b are diagrams for explaining the configuration of the first embodiment of the photodetector of this invention, and Figure 1a
Figure 1b shows a state in which the surface of the photodetector element is closed and the light input part can be replaced, and Figure 1b shows a state in which the surface of the photodetector element is open and can be measured, but the light input part cannot be replaced. shows.

In these figures, 9 is a photodetecting element, 10 is a mount for the photodetecting element 9, 11 is a light input section that guides input light, and 11a is an engagement formed on the side surface of the tip of the light input section 11. Groove as part, 1
Reference numeral 2 denotes an attachment/detachment restriction mechanism, which includes a plate-shaped shutter section 13 pivoted to open and close the surface of the photodetecting element 9 in close contact with the mount 10; It is composed of a stopper 14 as a blocking part that engages with the groove 11a, and is operated by scanning the knob part 15.

That is, in the photodetector of this invention, as shown in FIG.
Only when the surface of the photodetecting element 9 is protected by the groove 11a, the engagement between the groove 11a and the stopper 14 is released, and the optical input section 11 can be attached and removed. Therefore, as shown in FIG. 1b, when the surface of the photodetecting element 9 is not protected by the shutter section 13 and the groove 11a and the stopper 14 are engaged, the optical input section 11
Operate the knob 15 to remove the first
It is necessary to release the engagement as shown in Figure a.
On the other hand, since the shutter section 13 is also rotated with this operation and the surface of the photodetecting element 9 is also protected, the photodetecting element 9 is always protected when the optical input section 11 is attached or removed.

Furthermore, by using a click-stop mechanism or the like to configure the knob 15 so that it does not stop in the middle of opening and closing the shutter section 13, the light input section 11
Accidents that occur can be prevented by attaching and detaching.

FIG. 2 is a diagram for explaining the configuration of a second embodiment of this invention.

In this figure, the same reference numerals as in FIGS. 1a and 1b indicate the same parts, 16 is a receptacle for the optical fiber plug attached to the optical input section 11, 17 is a jacket, and 18 is an attachment/detachment restriction mechanism, all of which are integrated into one body. It is comprised of a shutter portion 19, a stopper 20, and a knob portion 21, and is rotatably held by a rotating shaft 22.

The main operation of this embodiment is almost the same as that of the first embodiment, but the structure is different from that of the knob 21.
The difference is that it is operated from the side of the photodetector.

Further, FIGS. 3a and 3b are diagrams for explaining the configuration of a third embodiment of this invention.

In these figures, the same reference numerals as in FIGS. 1a and 1b indicate the same parts, and 23 is an attachment/detachment limiting mechanism, which is composed of a shutter portion 24, a stopper 25, and a knob portion 26 that are integrally molded.

In the first and second embodiments described above, the shutter parts 13 and 19 are opened, closed and engaged by rotation, but in this embodiment, the knob part 22 is moved up and down. Accordingly, the shutter portion 24 is opened, closed, and engaged.

In addition, in the above embodiment, the stoppers 14, 20,
25 is shown as a plate-shaped one, but it goes without saying that it may also be a rod-shaped (pin-shaped) one.

Further, in the above embodiments, an example in which a thermal conversion type photodetection element is used has been described, but the present invention can be similarly applied to a photoelectric conversion type photodetection element.

In addition, the mechanism of this invention is a single mechanism that can handle both optical input part replacement and fiber attachment/detachment. Therefore, it is also possible to protect the photodetector.

[Effect of idea]

As explained above, this invention consists of a shutter part that protects the surface of the photodetecting element, and an engaging part of the optical input part that is attached to the connection part when the shutter part is in the open state and does not protect the surface of the photodetecting element. Since the connection part is equipped with an attachment/detachment restriction mechanism that is comprised of a blocking part that engages with the optical input part or prevents the optical input part from being connected to or removed from the connection part, it is possible to prevent optical detection by inadvertently attaching or disconnecting the optical input part. This has the effect of preventing fine dust from adhering to the surface of the element and reducing performance.

[Brief explanation of the drawing]

Figures 1a and b are diagrams for explaining the configuration of the first embodiment of the photodetector of this invention, and Figure 2 is a diagram for explaining the configuration of the second embodiment of this invention. Figures 3a and 3b are diagrams for explaining the configuration of the third embodiment of this invention, Figure 4 is a diagram for explaining an example of the configuration of the photodetecting element, Figures 5a and b, and 6 FIGS. a, b, FIGS. 7 a, b, and FIGS. 8 a, b, c are diagrams for explaining conventional photodetectors. In the figure, 9 is a photodetecting element, 10 is a mount, and 11
11a is the optical input part, 11a is the groove, 12, 18, 23 is the attachment/detachment restriction mechanism, 13, 19, 24 is the shutter part, 1
4, 20, 25 are stoppers, 15, 21, 26 are knobs, 16 is a receptacle, and 17 is a jacket.

Claims (1)

[Scope of utility model registration request] It has a connecting part to which a light input part for guiding input light having an engagement part formed at its tip is attached and detached, and the input light guided by the light input part is detected by a light detection element having therein. A photodetector comprising: a shutter portion that protects the surface of the photodetecting element; and the optical input attached to the connection portion when the shutter portion is in an open state not protecting the surface of the photodetecting element. A photodetector characterized in that the connecting portion is provided with an attachment/detachment restricting mechanism configured to engage with an engaging portion of the portion or to prevent attachment/detachment of the optical input portion to/from the connecting portion.