JPH026405Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rod lens with a holder, in which a cylindrical rod lens, such as a self-focusing lens, whose lens length is large compared to its diameter is integrally fixed to a lens holder.

A transparent cylindrical self-focusing lens with a distribution in which the refractive index is maximum on the central axis and gradually decreases parabolically toward the outer periphery is attached to the tip of an optical fiber to improve efficiency between it and other optical fibers or light receiving and emitting elements. It is widely used in elements that relay transmitted light, copying machine lenses, etc. The above self-focusing lenses generally have a lens diameter of 0.3 mm to 5 mm and a lens length that is approximately twice the lens diameter, making them extremely small and extremely elongated compared to general spherical lenses, so they can be ignored by normal spherical lenses. Possible problems such as the following have been highlighted.

In other words, when fixing an elongated cylindrical rod lens such as a self-focusing lens in a watertight state through an adhesive such as solder in the hole of a lens holder, the center axis of the lens holder hole and the optical axis of the lens must be aligned at a high height. If the inner diameter of the holder hole is made to be almost the same as the outer diameter of the lens in order to match the accuracy, it becomes extremely difficult to fill the adhesive between the inner wall of the holder hole and the outer circumferential surface of the lens. In order to maintain the properties, it is preferable to join the holder and the lens with solder, but if solder is used, it is necessary to have a large gap between them.

On the other hand, if the solder filling space is provided on the outer periphery of the lens, the optical axis of the lens will be significantly tilted within the holder hole with respect to the central axis of the hole.

The object of the present invention is to solve the above-mentioned conventional problems and provide a structure of a rod lens with a holder that allows for high alignment accuracy between the holder and the rod lens and also ensures reliable sealing between the holder and the lens.

The present invention achieves the above object by providing a rod lens with a holder, in which a cylindrical rod lens with a long lens length compared to its diameter, such as a self-focusing lens, is fitted into a hole of a lens holder and fixed together.
In the lens fitting hole, an alignment hole portion whose inner diameter is approximately the same as the lens outer diameter and extends at least 40% of the total length of the lens, and a bonding material filling hole portion whose inner diameter is larger than the alignment hole. A metal thin film 6 is coated in advance on the side peripheral surface of the rod lens 1, and the lens and holder are hermetically fixed with metal solder filled in the bonding material filled portion.

According to the above structure, there is no need to fill the alignment hole with bonding material, so the inner diameter of this hole can be made almost the same as the outer diameter of the lens, so the rod lens fitted in the holder is The tilting of the optical axis is reliably prevented by regulating the inner wall of the holder in the alignment hole portion, which has a long length, and the hole portion filled with bonding material does not require a function to restrict the tilting of the rod lens. It is possible to secure a large void where the amount of water can be retained, and it is also easy to fill.

Furthermore, the side surface of the lens is coated with a metal thin film in advance, and the holder and lens are fixed with solder filled in the bonding material filling hole of the holder, so it is difficult to insert a soldering iron into the microlens. Even near the center of the lens length direction, as shown in the example below, simply by inserting a ring-shaped solder wire into the bonding material filling hole and heating it from the outside of the holder, the solder will firmly adhere to the outer periphery of the lens. , the lens can be easily and securely fixed.

A detailed description will be given below based on the embodiments shown in the drawings. FIG. 1 is a longitudinal cross-sectional view of a rod lens with a holder according to the present invention. Reference numeral 1 is a self-focusing glass rod lens whose both end surfaces are parallel planes perpendicular to the optical axis, as an example of the rod lens. This rod lens 1 is housed in a lens fitting hole 2A of a metal lens holder 2 which is formed into a cylindrical shape and whose overall length is longer than that of the lens 1.

The inner diameter of the part of the lens fitting hole 2A where the rod lens 1 is located is made to match the outer diameter of the rod lens 1 with high precision (for example, the difference between both diameters is 10μ).
m or less) and an alignment hole 3 and a bonding material filling hole 4 having an inner diameter larger than the alignment hole 3 are formed.

The bonding material filling hole 4 consists of an annular groove whose inner diameter d4 is sufficiently larger than the inner diameter d3 of the alignment hole 3, and is provided at three locations in the longitudinal direction of the rod lens 1, near both end surfaces of the lens and in the middle of the lens. There is. The above-mentioned alignment hole 3 is formed between these three grooves 4. Regarding the length of the alignment hole 3, if the length of this part is too short, there is a risk that the rod lens 1 may tilt inside the hole. The total length of the wall is at least 40 times the total length of the rod lens.
It is necessary to secure at least 60%.
% or more is preferable. Each bonding material filling hole 4 is filled with a bonding agent 5 made of low-melting metal solder in a ring shape around the entire lens circumference, and this bonding agent 5 seals the gap between the inner wall of the lens holder 2 and the side peripheral surface of the rod lens. At the same time, both 1 and 2 are fixed. Here, if the groove depth of the bonding material filling hole 4 is too shallow or the width is too small, it becomes difficult for solder to enter, so the width W of one bonding material filling hole 4 is
The groove depth must be at least 0.5 mm, preferably 0.8 mm or more, and the groove depth must be at least 0.05 mm, preferably 0.8 mm or more. Further, in order to facilitate soldering between the metal holder 2 and the glass rod lens 1, the side peripheral surface of the lens 1 is coated with two layers of metal thin film 6. There are no particular restrictions on the material of the metal thin film 6, but a combination of nickel as the base layer and gold as the surface layer, or a combination of nichrome as the base layer and gold, platinum or rhodium as the surface layer can be suitably used.

As described above, it is desirable to provide a multilayer coating on the outer periphery of the rod lens, in which a surface layer made of noble metal or the like is provided with excellent weather resistance and solderability on a base layer with good glass adhesion and solderability.

A preferred method for manufacturing a rod lens with a holder having the above structure is shown in FIG. As shown in the figure, a ribbon solder 7 formed into an extremely thin line is initially embedded in the bonding material filling hole 4 so as not to protrude inward beyond the inner surface of the alignment hole 3, and the rod lens 1 is fitted into the alignment hole 3. After mounting, the holder 2 is heated from outside with a heater 8 to melt the solder.

Another embodiment of the invention is shown in FIG. In this example, the alignment hole 3A extends from one opening side of the lens holder outer cylinder 10 to a certain depth.
A bonding material filling hole 4 with a constant inner diameter is formed from one end to the other open end of the outer cylinder 2, and this hole 4 and the alignment hole 3A
Solder 5 as a bonding material at the position in contact with the boundary wall between
Fill the entire circumference of the rod lens to seal between both 1 and 2 and fix them both, and from the open end side of the bonding material filling hole 4, align the outer diameter with the inner diameter of the hole 4,
It has a structure in which a metal inner tube 9 whose inner diameter matches the outer diameter of the lens 1 is installed.

In the structure of this example, the lens holder 2 is composed of two parts: an outer cylinder 10 and an inner cylinder 9. Both are provided with alignment holes 3A and 3B, respectively, and together form an alignment hole 3 of a predetermined length. Both cylinders 9 and 10 are connected by solder 5.

When manufacturing the above structural product, initially the inner cylinder 9
With the ring-shaped solder material 7 removed, a ring-shaped solder material 7 is inserted into the boundary wall 11 of the bonding material filling hole 4 of the outer cylinder 10, and then the inner tube 9 is inserted into the bonding material filling hole 4. Next, the rod lenses 1 whose side peripheries are coated with metal thin films are fitted into the alignment holes 3A and 3B of both cylinders 9 and 10, and then heated from the outside with a heater 8 to melt the solder material 7.

Although the present invention has been described above with reference to the embodiment shown in the drawings, the present invention is not limited to the illustrated example and can be modified in various ways. For example, in the example shown in FIG. 1, the number of bonding material filling holes 4 is arbitrary, and as long as a predetermined length of the alignment hole 4 is secured, four or more, one or two may be provided. . Furthermore, the structure may be such that the inner cylinder 9 is omitted in the example shown in FIG. Further, the bonding material 5 is filled with the bonding material filling hole 4.
It is also possible to fill not only the inside but also the inside of the alignment hole 3. Further, the rod lens 1 is not limited to a self-focusing type lens, but may be, for example, an end-face condensing type lens in which one side of a transparent cylindrical body having a uniform refractive index is spherical and the other side is flat.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing one embodiment of the present invention, Fig. 2 is a longitudinal sectional view showing a preferred method for manufacturing the product shown in Fig. 1, and Fig. 3 is a longitudinal sectional view showing another embodiment of the invention. The plan view and FIGS. 4A and 4B are longitudinal cross-sectional views showing a preferred method for manufacturing the product shown in FIG. 3. 1... Rod lens, 2... Lens holder,
3, 3A, 3B...Axis alignment hole, 4...Binding material filling hole, 5...Binding material, 7...Solder material, 8...Heater, 9...Inner cylinder, 10...Outer cylinder.

Claims (1)

[Scope of utility model registration request] A cylindrical rod lens 1 with a long lens length compared to its diameter, like a self-focusing lens, is mounted on a lens holder 2.
In the rod lens with a holder that is fitted into the hole 2A and fixed integrally, the lens fitting hole 2A
a 3 portion of the alignment hole whose inner diameter is almost the same as the outer diameter of the lens and extends at least 40% of the total length of the lens; and a 4 portion of the bonding material filling hole whose inner diameter is larger than the alignment hole 3; , and the rod lens 1
A rod lens with a holder, characterized in that a metal thin film 6 is coated in advance on the side peripheral surface of the lens, and the lens and the holder are hermetically fixed with metal solder filled in the bonding material filling hole 4.