JPS58176613A - Feedthrough device for optical fiber - Google Patents

Abstract

PURPOSE:To align the axes of both connector receptacles only when the receptacles are mounted mechanically to a hermetic wall and to assure the axial alignment between both optical fibers with the accuracy of the connector after the above-mentioned alignment. CONSTITUTION:The parts near the opening ends of respective optical fibers are disposed and fixed in connector jacks or connector pins 6a, 6b which are male connector elements among the male and female connector elements of an optical fiber connector and the connectors pins are received by respective receptacles 7a, 7b as female connector elements. The receptacles 7a, 7b are fixed mechanically by means of screws or the like to a hermetic wall 1 as shown by virtual lines 8a, 8b. Optical passages 9a, 9b leading to the respective planes of a window 4 are formed to the receptacles 7a, 7b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber feed-through device for transmitting and receiving optical signals through an airtight wall.

It is often desirable to send and receive information signals through an airtight wall that keeps the spaces on both sides spatially separated. for example,
Various types of vacuum equipment have electronic circuit systems such as digital circuits sealed inside to perform the required functions.Of course, when communicating between this internal electronic circuit system and the outside, Such a request is made. Therefore, previously,
This was done by a feed-through device for electrical signals through electrical wires. A feed-through device is a device that passes a signal through an obstacle, as in the example above, but in conventional electrical feed-through devices, the signal-to-noise ratio (S, m) is There were cases where there was no good harvest, which caused problems.

Therefore, conventionally, electrical signal 0 is converted into optical signal,
There have been requests to perform feed-through using this optical signal, but a feed-through device that is easy to handle and has high performance has not been developed for the optical 7-eyeper as a transmission medium for such optical signals. There wasn't.

In view of this point, the present invention aims to provide an optical fiber feed-through device that can satisfactorily transmit and receive optical signals through an airtight wall. .

FIG. 1 shows a first embodiment of the invention.

For convenience, in this ζ, it is assumed that the airtight wall l in several vacuum devices is a metal wall such as stainless steel, and separates the external environment on the left hand from the vacuum environment on the right hand in the drawing.

A through hole is bored in the airtight wall l, and a sleeve 3 is fitted into the inner wall surface of the through hole. The sleeve 3Fi is brazed to the through hole as shown by the point PI -3%, for example. This sleeve is a holding member that holds an optical window made of light-transmitting forest material that allows optical signals to pass through while blocking the interior and exterior space.

The window ≠ is also fixed to the holding member or sleeve 30 step portion by brazing as illustrated at points P, , P,.

An optical fiber jα for an external circuit and an optical fiber j6 for an internal circuit of the device are arranged with the ginseng in between, with their end faces or open ends facing each other, but in this device, these pair of opposing optical fibers j.

In order to facilitate the removal and reattachment of j6 and to avoid the trouble of axial alignment each time, each optical fiber is detachably fixed in a predetermined position using a commercially available optical fiber connector.

That is, the portion near the open end of each optical fiber is arranged and fixed in the connector jack or connector pin a, g of the male connector element in the male and female connector elements of the optical fiber connector, and this connector pin is used as the female connector element. each receptacle 7a.

7b is set as a trap to accept the receptacle 7.
g, 7b are mechanically fixed to the airtight wall lK using screws (not shown) or the like as shown by virtual lines 1a, 1rl). Of course, each receptacle'a
In +7b, optical paths 2G and 2b leading to each side of the ginseng are formed.

According to such a configuration, if the axis alignment is initially achieved only when mechanically attaching both connector receptacles 7a and 7b to the airtight wall l, then the axis alignment between the two party fibers jGejh can be achieved with connector precision. Considering that current connectors have very high axis alignment accuracy and therefore low loss, the feed-through device of the present invention does not significantly increase loss due to the use of connectors. This will not be considered a problem, and people will buy it for its ease of use.

However, as schematically shown in FIG. 1, when the distance between the end faces of both optical fibers or the opening end faces becomes large, loss may become a problem. In such cases,
As in this embodiment, if one collimator lens to(z, tab is placed in each optical path α, b that sandwich one window lens),
Losses can be limited.

In this example, a lens holder //cL, /II) that holds a collimator lens ioα, 107) is used, one holder 1o (z is fixed by one receptacle 7a and sleeve J, and the other The retainer//b is rather large, and the receptacle 7b is fixed to the airtight wall/by a screw RB via this retainer/lb.

On the other hand, if the ends of both fibers are placed in extremely close proximity to each other, there is no problem in omitting the collimator lens. FIG. 2 shows such an embodiment, in which the same reference numerals as in FIG. 1 indicate components that are the same or similar to those in the previous embodiment, and include a ginseng holding member 3 that blocks and separates the spaces on both sides.
was changed from a sleeve-shaped member to a disc-shaped member, and this disc-shaped holding member was attached to the stepped portion formed on the inner surface of the through-hole of the airtight wall l, as shown by point R-Pa. ing. The connector includes connector pins 6a,
6b is each receptacle 7a.

A type that penetrates deeply into the 7b is used. There is.

By the way, in this device, the reason why the window is not attached directly to the airtight wall and is attached via the holding member 3 has the following practical meaning.

Generally, the airtight walls of vacuum equipment and the like are often made of stainless steel. On the other hand, since it is better for ginseng to have a small transmission loss, it is desirable to use highly pure quartz glass if possible, and to make the wall thickness sufficiently thin within the range that mechanical strength allows. However, when quartz glass is attached directly to stainless steel, due to the difference in coefficient of thermal expansion, cracks may appear in the window due to changes in the temperature environment, brazing may damage the part due to stress, and the airtightness may be compromised. There is a risk of it breaking.

Therefore, after attaching the window to a holding member 3 such as a metal member whose coefficient of thermal expansion is the same or very similar to that of the window,
This holding member was attached to the airtight wall l.

In fact, the best combination of materials for the ginseng and the holding member J is not quartz glass but sapphire for the ginseng and kovar for the holding member 3.

Compared to quartz glass, sapphire has a large transmission loss at the same thickness, but this combination has much higher mechanical strength and excellent airtightness, so the wall thickness is lower than when using quartz glass. Since the window can also be made sufficiently thin, the result is a sapphire window with comparable low-loss characteristics, and even superior low-loss characteristics.

Of course, other combinations can be freely designed by balancing both intensity and optical loss.

As described above, according to the present invention, it is possible to provide a feed-through device that allows easy attachment and detachment of optical fibers, can easily be expected to reduce loss, is resistant to electromagnetic disturbances, and can handle large amounts of data. This allows the advantage of optical signal communication, which is transportable, to be fully utilized.

[Brief explanation of drawings]

1 and 2 are schematic configuration diagrams of first and second embodiments of the apparatus of the present invention, respectively. In the figure, l is an airtight wall, 3 is a window holding member, da is an optical window, and j
α, zb are optical fibers, tα, 66 are connector pins = y,
7a, 7bu connector receptacle, /θa. 10b is a collimator lens.

Claims (1)

[Claims] An optical fiber feed-through device for transmitting and receiving optical signals between a pair of optical fibers with their end faces facing each other with an airtight wall in between, the device being held in a through hole bored in the airtight wall. an optical window that is fixed via a member to maintain airtightness and is optically transparent; and an optical path that faces each other with the optical window in between and that is axially aligned with each other toward each surface of the skeleton optical window; An optical fiber feed-through device comprising: a connector receptacle fixed to each corresponding surface of the airtight wall; and a connector pin having the optical fiber inside and being received in the connector receptacle.