JPH01319710A - Incident position adjusting device for light beam - Google Patents

Abstract

PURPOSE:To facilitate the position adjustment at the time of casting a light beam through a condenser lens to a light transmission fiber and to improve the incident efficiency by holding a lens holder in which the thick condenser lens is built oscillatably by the fulcrum at one end thereof and varying the angle of inclination. CONSTITUTION:The thick condenser lens 15 is used as the condenser lens to condense the light beam 10 by the condenser lens 15 and to cast the same to the light transmission fiber 14. This lens is built into the lens holder 16 and is held oscillatably by the fulcrum 18 at the end on the incident side. The incident light on an object side main plane H1 at an incident angle theta is emitted at an exit angle theta from an image side main plane H2 and enters the light transmission fiber 14 existing in the focal position when the lens 15 is inclined by angle theta with respect to the light beam 10. This focal position is determined by the relation between the distance delta and angle theta of the light beam 10 and the light transmission fiber 14. The incident angle can, therefore, be adjusted simply by inclining the thick condenser lens 15 around the fulcrum 18 even if the light transmission fiber 14 is installed apart from the main ray position of the light beam 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for efficiently injecting a light beam such as a gas laser or a semiconductor laser into an optical transmission fiber, and more specifically relates to a device for efficiently injecting a light beam such as a gas laser or a semiconductor laser into an optical transmission fiber. This invention relates to a light beam incident position two adjustment device in which a condenser lens is installed so that its inclination angle can be freely changed.

[Prior Art] In the prior art, as shown in FIG. 4, a light beam 10 generated from a gas laser, a semiconductor laser, etc. is condensed by a condenser lens 12 and sent to an optical transmission fiber 14. In order to efficiently input the optical beam IO into the optical transmission fiber 14, the optical transmission fiber 14 needs to be arranged with high accuracy with respect to the optical beam 10, and the assembly accuracy will affect the input efficiency. .

One of the causes of deterioration of the incidence efficiency is that the principal ray position of the light beam incident on the optical transmission fiber 14 does not match the core position of the optical transmission fiber 14. Therefore, the optical transmission fiber 14 must be precisely adjusted so that its core position is at the position where the light is focused by the condensing lens 12. Such adjustment requires that the optical fiber 14 be installed by moving the position. This will be done by

[Problem to be solved by the invention] However, when a single mode fiber is used as the optical transmission fiber 14, the core diameter (diameter) is 10
Since it is very small, less than μm, the adjustment precision of the principal ray of the optical beam IO incident on it must be made very high.

As mentioned above, when using a single mode fiber, adjustment with an accuracy of 1 μm or less is required. However, a turbulent table whose position can be adjusted with high accuracy of 1 μm or less is expensive and requires a lot of damage to the device.

In addition, the adjustment work involved is very difficult, and there is a good possibility that high incidence efficiency cannot be obtained because the assembly accuracy is insufficient.

The purpose of the present invention is to eliminate such drawbacks of the prior art,
It is an object of the present invention to provide a light beam incident position adjustment device that can easily adjust the position when the light beam is incident on an optical transmission fiber through a condensing lens, thereby increasing the incidence efficiency.

[Means for Solving the Problems] As shown in FIG. 1, the present invention, which can achieve the above object,
This is a device in which the light is focused by a condensing lens 15 and incident on the optical transmission fiber 14. A thick lens is used as the condensing lens 15, and the inclination angle of the condensing lens 15 is made variable.

Here, the thick-walled condensing lens 15 is incorporated into a lens holder, and the lens holder is swingably held at one end by a fulcrum, and at the other end, the lens holder is held substantially perpendicular to the central axis of the lens holder. It is supported by a three-point support mechanism that is adjustable in two directions. If the inclination angle of the thick condensing lens 15 is θ, then the angle θ can be changed freely.

[If the thick condensing lens 15 is arranged at an angle θ with respect to the working light beam IO, the light beam IO will be
The light enters the object-side principal plane H, at an incident angle θ, and exits from the image-side principal plane H2, located a distance d away, at an exit angle θ.

The light then enters the optical transmission fiber 14 at the focal position.

This focal point position is located at a distance δ from the principal ray of the light beam 10, and the relationship between the distance δ and the angle θ is δ=d−sinθ...+11. Therefore, even if the optical transmission fiber 14 is installed away from the position of the chief ray of the light beam 10, it is understood that the thick condensing lens 15 can be tilted so as to satisfy the above equation +11.

The reason for using a thick lens as the condensing lens 15 here is that the object-side principal plane H+ and image-side principal plane H8 must be spaced apart as described above, and a thin lens cannot be used in this way. This is because it is not possible to make a 111 arrangement.

[Example] How accurately the position of incidence on the optical transmission fiber 14 can be adjusted depends on how accurately the inclination angle θ of the lens holder 16 can be adjusted. FIGS. 2 and 3 show an example of a specific support structure for the lens holder 16. FIG.

The lens holder 16, in which the thick condensing lens is incorporated, has a generally cylindrical shape as a whole, and has notches 16a and 16b formed at right angles to each other on the outer periphery on the exit side. This lens holder I6 is swingably held by a fulcrum 18 at its end on the incident side. This fulcrum 18 has a structure similar to, for example, a gyroscope, and its output side end is
It is held so that it has degrees of freedom in the axial direction and the Y-axis direction. An adjustment point is provided on the exit side of the lens holder 16. This adjustment point is a three-point support mechanism consisting of 1lli bar screws 20a and 20b that abut the notches 16a and 16b, respectively, and a spring 22 located on the opposite side thereof. A fixing screw 24 is provided inside the spring 22.

For example, when the adjustment screw 20a is rotated, the lens holder 16 moves forward or backward by a distance, and the end of the lens holder 16 is displaced in the Y-axis direction against the force of the spring 22.

This makes it possible to vary the inclination angle of the lens holder 1G and, by extension, the inclination angle θ of the thick condensing lens 15. Once the adjustment is completed, the cap screw 24 can be rotated to bring it into contact with the outer peripheral surface of the lens holder 16. Can be fixed in position.

When the adjustment screw 20a moves by the distance, the inclination angle θ of the thick condenser lens 15 is θ=jan-' (h/a)-
・(It becomes 21.

Here, the distance a between the fulcrum 18 and the adjustment point on the lens holder 16 is 80 mm, in! Screw 20a at the node
, 20b is set at a pitch of 0.5 mm +, and the rotation angle of the adjustment screw can be adjusted in 5 degrees using a screwdriver, etc.,
The resolution in the axial direction of the screw is hc=0.5・(5/360)=6. The inclination angle θ of the lens holder 16 when the UR node changes by this resolution hC, which is 94x 100-2(+*). is θ, -tan-'
(he / a) = jan visit (6,94X 10-
"/80) = 4.97xlO-' (degrees). At that time, the resolution δ of the positional shift adjustment of the principal ray of the light beam in FIG. The distance d between the image-side principal plane H! and the image side principal plane H! is 21
1II11 is used, δc =2. OO-5in (4,97x 10-
')=1.73X10-'(m+w)=0.173 (μm), 1. Adjustment below c+m is possible. From the above description, it can be seen that the present invention allows the position of the incident light beam to be adjusted with sufficient precision against the positional deviation of the optical transmission fiber.

Although a preferred embodiment of the present invention has been described in detail above, it is not limited to such a support mechanism.In the above-mentioned structure in which the hood is supported by the hood fulcrum and the adjustment point, the distance between them is set to 101111 or more. It is desirable to do so.

[Effects of the Invention] As described above, the present invention uses a thick lens as a condensing lens, and has a structure in which the inclination angle of the lens can be adjusted. Therefore, by adjusting the angle, the position of the principal ray of the light beam is shifted, and light transmission is possible. It has the excellent effect of being able to match the position of the fiber and increasing the incidence efficiency.

In particular, we adopted a three-point support mechanism in which one end can be held swingably by a fulcrum, and the other end can be adjusted in position by adjusting screws in two axes perpendicular to the optical axis. The inclination angle of the lens holder can be finely adjusted with a high precision of 1 μm or less, and all you have to do is measure the amount of light received by the optical transmission fiber and rotate the adjustment screw to obtain the maximum amount of light. This has the effect that even an unskilled person can easily and quickly adjust the incident position without requiring any skill.

Furthermore, the structure is much simpler and smaller than that of the fine movement table, and it is very inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic configuration of a light beam incident position adjusting device according to the present invention, FIG. 2 is a side view showing an example of the support structure of the lens holder, and FIG. 3 is a front view thereof. FIG. 4 is an explanatory diagram showing the prior art. 10... Light beam, 12... Condensing lens, 14...
・Optical transmission fiber, 15... Thick condensing lens, 16
... Lens holder, 1B... Fulcrum, 20a. 20b...adjustment screw, 22...spring. Patent applicant Nippon Sheet Glass Co., Ltd.

Claims (1)

[Claims] 1. A device for condensing a light beam and making it enter an optical transmission fiber, in which a lens holder incorporating a thick condensing lens is swingably held by a fulcrum at one end, and 2, which is approximately perpendicular to the central axis of the lens holder.
A light beam incident position adjusting device characterized in that the light beam is supported by a three-point support mechanism that is adjustable in direction.