JPH0343723Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a ring laser gyroscope used for detecting rotational angular velocity.

[Technical background of the invention and its problems] In general, a ring laser gyro travels in opposite directions to a ring resonator in which three or more glass blocks are arranged to form an annular optical path. When the first and second lasers (lights) are present and the ring resonator is given an angular velocity around the direction (input axis) perpendicular to the plane created by the optical path, the Sagnac effect causes , a difference in optical path between the traveling waves of a laser traveling in two directions, that is, a difference in oscillation frequency occurs. Since the magnitude and sign of this oscillation frequency difference correspond to the magnitude and direction of the angular velocity applied around the input axis, the first and second lasers are connected at one point using an optical mixing prism. By mixing, an interference light beam having a beat frequency is extracted, and the rotational angular velocity is detected from this beat frequency.

By the way, the above-mentioned ring laser gyroscope is designed to form interference fringes by overlapping the first and second lasers at an angle of several mrad using a light mixing prism, so two detectors are set at the wavelength of the interference fringes. The direction of the input angular velocity is detected by disposing them at intervals of 1/4 of the angular velocity.

However, due to the structure of the ring laser gyroscope, the light receiving parts of the two photodetectors are placed close to each other by about 0.3 mm when the beam diameters of the first and second lasers are about 0.7 mm. Since the interference fringes 2 of the interference light beam 1 must be formed as shown in FIG. 5, the adjustment work is extremely complicated.

For this reason, in one example, a beam expander such as a concave lens is arranged on the light output side of the light mixing prism to expand the interference fringes, thereby simplifying the above adjustment work. However, the problem was that the device was large-scale and its structure was extremely complicated.

[Purpose of the invention] This invention was made in view of the above-mentioned circumstances, and the purpose is to provide a ring laser gyroscope that has a simple configuration and is capable of improving adjustment work and measurement accuracy as much as possible. With the goal.

[Summary of the invention] In other words, this invention provides a concave portion at a predetermined position of an optical mixing prism that takes out the interference light beam of the laser traveling in two directions, and uses this concave portion to enlarge the interference fringes of the interference light beam of the laser. By configuring it as follows, the intended purpose was achieved.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.

FIG. 1 shows a ring laser gyroscope according to an embodiment of this invention, and 10 in the figure is a glass block including a laser traveling path formed in an annular shape of low expansion glass, for example. This glass block 10
For example, the first and second concave reflecting mirrors 11 and 12 and the first and second flat reflecting mirrors 13 and 1 are installed at its four corners.
A ring resonator 15 is configured such that the laser (light) passes through the ring resonator 4 repeatedly.
A He-Ne mixed gas is sealed. Of these, for example, the first plane reflecting mirror 13 is provided with a light mixing prism 16 for extracting the interference light beam.
This light mixing prism 16 has a transmittance of, for example, 0.05 to
The light transmitted through the first plane reflecting mirror 13 set at 0.5% is superimposed at an angle of several mrad as shown in FIG. Concavity 17 for enlarging interference fringes
(see Figure 3) is formed. Further, first and second anodes 18 and 19 made of a glass-sealing metal (such as Kovar) and tungsten material are provided at both ends of the glass block 10 to face each other, and in the middle thereof, A cathode 20 made of copper, aluminum alloy, or the like is provided.

In the above configuration, when the ring resonator 15 is rotated around an axis perpendicular to the optical path configured within the glass block, an optical path is formed between the laser beams oscillated in opposite directions within the ring resonator 15. A difference occurs, and an interference light beam 21 having a beat frequency is output from the optical mixing prism 16. At this time, as shown in FIG. 4, the interference fringes 22 of the interference light beam 21 are enlarged and taken out by the concave portion 17 of the optical mixing prism 16, and a photodetector (not shown) detects the above-mentioned beat frequency. is read and the rotational angular velocity is detected.

In this way, the ring laser gyroscope is provided with a recess 17 at a predetermined position of the light mixing prism 16 that takes out the interference light beam 21 of the laser traveling in two directions, and this recess 17 allows the laser beam to be placed within a narrow beam diameter of, for example, about 0.7 mm. Since the structure is configured to expand the interference fringes 22 of the laser interference light beam 21 formed by the laser, adjustment of the photodetector is made as simple as possible, the workability is improved, and measurement accuracy is improved. This can be promoted.

Further, in the above embodiment, this invention has been explained in the case where the curved concave portion 17 is formed in the light mixing prism, but the present invention is not limited to this, and it is also possible to configure the concave portion 17 to be formed in a spherical shape, for example. It is.

It goes without saying that this invention is not limited to the above embodiments, and that various modifications can be made without departing from the gist of this invention.

[Effects of the invention] As detailed above, according to this invention, it is possible to provide a ring laser gyroscope that has a simple configuration and is capable of improving adjustment work and measurement accuracy as much as possible. can.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration of a ring laser gyroscope according to an embodiment of this invention, Fig. 2 is an enlarged view showing the main parts of Fig. 1, and Fig. 3 shows the light mixing prism shown in Fig. 1 taken out. Fig. 4 is an interference fringe pattern diagram shown to explain the operation of Fig. 1;
The figure is an interference fringe pattern diagram shown to explain conventional problems. 10...Glass block, 11...First concave reflecting mirror, 12...Second concave reflecting mirror, 13...First plane reflecting mirror, 14...Second plane reflecting mirror, 1
5...Ring resonator, 16...Light mixing prism,
17... recess, 18... first anode, 19...
...Second anode, 20...Cathode, 21...
Interference light beam, 22... interference fringes.

Claims (1)

[Scope of utility model registration request] First and second lasers traveling in opposite directions are present in a ring resonator in which three or more reflecting mirrors are arranged on a glass block to form an annular optical path. In a ring laser gyroscope that detects rotational angular velocity by measuring the difference in the oscillation frequency of the lasers, the interference light beams of the first and second lasers are extracted from the ring resonator, and a recess is formed at a predetermined position. A ring laser gyroscope characterized by comprising a light mixing prism having a light mixing prism.