JP2833288B2 - Optical filter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter device, and more particularly to an optical filter device for adjusting a wavelength range of light to be transmitted by adjusting an incident angle of light on a filter plate.

[0002]

2. Description of the Related Art FIG. 3 shows a pigtail type optical filter as an example of a conventional optical filter. In this conventional example,
Rotating the filter plate 6 from a direction perpendicular to the optical axis to adjust the incident angle of the beam passing through the optical filter plate 6;
That technique was adopted. In the mechanism shown in FIG. 3, since the rotation angle of the adjustment portion changes the incident angle, when finely adjusting the incident angle, the rotation angle is converted using the gear 7 or the like.

[0003]

In this conventional optical filter, since the angle of incidence is adjusted from a direction perpendicular to the optical axis, the housing is box-shaped, and processing is difficult. Further, when finely adjusting the incident angle, a gear or the like is used, so that the structure is complicated and the productivity is poor.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art and to provide an optical filter device having a simple structure and capable of finely adjusting the incident angle with high accuracy. I do.

[0005]

According to the present invention, in order to adjust the angle of incidence of light on the filter plate, a female screw which is inclined with respect to the optical axis of a beam passing through the filter plate is fitted . Piece
There is a mechanism for fixing and rotating the filter plate to a hollow male screw whose one end face is not perpendicular to the central axis.

[0006]

In this adjusting mechanism, when the inclination of the central axis of the female screw and the optical axis passing through the filter plate is small, the incident angle can be adjusted from a direction substantially parallel to the optical axis. Being coaxial, processing becomes easier. The inclination between the normal line of the filter plate and the central axis of the male screw is a [degree], and the inclination between the central axis of the female screw and the optical axis passing through the filter plate is b [degree].
Then, the incident angle can be adjusted in the range of b ± a [degree], and the change of the incident angle while rotating the male screw by 360 degrees is 2 degrees.
Since the angle is a [degree], the incident angle can be finely adjusted by appropriately selecting the value of a [degree].

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The embodiment shown in FIGS. 1 and 2 has a case 3 provided with a through-hole through which a beam passes, and at least one end face having a face slightly inclined with respect to the center axis and having a light at the center. A male screw 4 having a transmitting portion, and an optical filter plate 5 fixed to the inclined surface and transmitting only light in a specific wavelength range.
And a female screw 3 </ b> A provided in a through hole of the case 3 and screwed to the male screw 4. This female thread 3A
Is set to be appropriately inclined with respect to the optical axis of the beam passing through the optical filter plate (in FIG. 1, inclined by θ degrees).

More specifically, the embodiment shown in FIGS. 1 and 2 shows an application example in which the present invention is applied to a pigtail type optical bandpass filter. The pigtail cord 1 is a dispersion-shifted fiber and is connected by a lens 2. The case 3 is a coaxial type having a diameter of 7 [mm] and has a filter plate 5.
4 degrees with the optical axis of the beam passing through
A is cut. The optical band-pass filter plate 5 has an incident angle θ
Is changed from 0 degree to 8 degrees, the pass center wavelength changes from 1.550 [μm] to 1.555 [μm]. The optical band-pass filter plate 5 is hollow, one end face of which is not perpendicular to the central axis, and is fixed to the male thread 4 of M5 at an angle of 4 degrees with respect to the central axis of the male thread. Male screw 4
By fitting and rotating the female screw 3A of the case 3, the incident angle changes from 8 degrees shown in FIG. 1 to 0 degrees shown in FIG. Therefore, the passing wavelength is set to 1.55
It can be adjusted in the range of 0 [μm] to 1.555 [μm].

The adjustment range of the incident angle can be changed depending on the angle between the optical axis and the female screw 3A and the shape of the male screw 4, whereby the adjustment range of the passing wavelength can be changed. The pass band is controlled by the optical band pass filter plate 5.
An arbitrary wavelength band such as a 1.55 [μm] band and a 1.31 [μm] band can be selected. In addition to using the male screw 4 and the female screw 3A as the rotation mechanism of the filter, application of a fitting hole can be considered.

The filter plate may be a low-pass filter plate or a high-pass filter plate in addition to the optical band-pass filter plate. The method of the present invention can be used not only as a pigtail type optical filter but also when a light emitting / receiving module incorporates an optical filter, or when a passive device such as a coupler or an isolator is combined with an optical filter. .

[0012]

As described above, according to the present invention, in order to adjust the angle of incidence of light on the filter plate, it is fitted to a female screw inclined with respect to the optical axis of the beam passing through the filter plate. At least one end face has a mechanism to fix and rotate the filter plate to a male screw that is not perpendicular to the center axis, so that the housing becomes coaxial and processing becomes easier, the structure becomes simpler, and the inclination change is continuous. In addition, it is possible to provide an unprecedented excellent optical filter device that can be set finely.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Pigtail cord 2 Lens 3 Case 4 Holder 5 Optical bandpass filter plate

Claims (2)

(57) [Claims] 1. A case having a through hole through which a beam passes
A male screw having one end face slightly inclined with respect to the central axis and having a light transmitting portion in the center, and an optical filter plate fixed to the inclined face and transmitting only light in a specific wavelength range And a female screw provided in the through hole of the case and screwed into the male screw, wherein the central axis of the female screw is appropriately inclined with respect to the optical axis of the beam passing through the optical filter plate. An optical filter device characterized by the following. 2. The optical filter device according to claim 1, wherein the light transmitting portion at the center of the male screw is formed with a through hole.