JPH0535804B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a cylindrical laser gyroscope using a cylindrical gyroscope body, and more specifically, a cylindrical laser gyroscope that processes the outer peripheral surface of the cylinder to form a confocal mirror. ,
This invention relates to a cylindrical laser gyroscope which prevents the beam diameter from expanding infinitely even after repeated reflections.

(Prior art) A laser gyro has a Sagnac interferometer configuration as shown in Fig. 5, and the light emitted from the light source A is divided by C into a clockwise and counterclockwise optical path, and when the laser gyro system rotates, An optical path difference occurs between clockwise and counterclockwise rotations depending on the angular velocity. Due to the optical path difference, the interference fringes caused by the two light waves move, and the angular velocity can be detected.

FIG. 6 is a perspective view showing a conventional example of a cylindrical laser gyro.

In FIG. 6, 1 is a gyro body, 2 is a beam splitter, 3 is a laser light source, 4 is a clockwise emission light detector, 5 is a counterclockwise emission light detector, and 6 is an arithmetic unit.

The gyro main body 1 is made of transparent quartz. On the outside of the cylindrical outer periphery of the gyro main body 1, a reflective film 1a made of, for example, aluminum vapor deposition is provided so as to reflect light efficiently. The gyro body 1 also has a clockwise entrance surface (counterclockwise exit surface).
1b, and a counterclockwise entrance surface (clockwise exit surface) 1c are provided.

A beam splitter 2 is arranged at a position that bisects the angle between each side of the gyro body 1, and makes incident light from a laser light source 3 enter the gyro body 1. The light enters the gyro body 1 from the clockwise entrance surface (counterclockwise exit surface) 1b, is reflected many times, and exits from the counterclockwise entrance surface (clockwise exit surface) 1c.
It is detected by the clockwise emission light detector 4.

Similarly, light enters the gyro body 1 from the counterclockwise entrance surface (clockwise exit surface) 1c, is reflected many times, and is emitted from the clockwise entrance surface (counterclockwise exit surface) 1b. Detected by 5.

The detection results are compared by a calculator 6, and the angular velocity applied to the gyro can be output.

FIG. 7 is a schematic diagram showing an example of an optical path within the gyro body.

In Figure 7, the clockwise light is a → 2 (reflection)
→1b→M ₃ →M ₄ ~M ₁₁ → Follows the path of 1c and emits. The counterclockwise light is a → 2 (transmission) → M ₁₁ ~ _{M 3} →
It emits by following the path 1b.

Assuming that the gyro body 1 is placed in a stationary system, there should be no difference in optical path length between the clockwise and counterclockwise directions. If the gyro main body 1 is placed in a rotating system centered on the center of a cylinder, an optical path difference will occur due to the aforementioned Sagnac effect, but detection is possible even if the center of the cylinder is not necessarily at the center of the rotating system. Therefore, an optical path difference occurs in the laser beam,
The rotational angular velocity of the system can be detected.

(Problems to be Solved by the Invention) The aforementioned cylindrical laser gyroscope employs a cylinder as its basic shape. In this case, when reflection is repeated on the circumference or when a beam of light that is slightly diverging or converging is reflected, the light beam gradually spreads out on the reflecting surface. As a result, the beam diameter increases and optical loss increases, resulting in a problem that the function as a gyro deteriorates.

An object of the present invention is to provide a cylindrical laser gyroscope whose outer circumferential surface is processed to form a confocal mirror, and whose beam diameter is prevented from increasing infinitely even after repeated reflections.

(Means for Solving the Problems) In order to achieve the above object, the cylindrical laser gyroscope according to the present invention is a gyroscope in which a cylindrical optical reflection surface and a laser light input and output surface are provided on the outer periphery of a transparent optical material. a main body; a beam splitter disposed corresponding to the incident and exit surfaces; a laser oscillator that projects laser light into the gyro main body in clockwise and counterclockwise directions via the beam splitter; A cylindrical laser gyroscope comprising a detector that detects a phase difference between a laser beam reflected and rotated clockwise and emitted within the gyroscope body and a laser beam emitted after multiple reflections in the counterclockwise direction. The outer peripheral reflective surface is a concave surface facing the central axis, and its focal length is configured to be approximately equal to the distance to the next outer peripheral reflective surface at which the reflected light of the laser beam reaches.

The outer circumferential reflective surface of the gyro main body can have a cross-sectional shape including its central axis in a quadratic curve, a straight line, or a combination of quadratic curves.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a perspective view showing an embodiment of a cylindrical laser gyro according to the present invention, and FIG. 2 is a diagram showing an embodiment of a gyro body used in the cylindrical laser gyro according to the present invention.

It should be noted that the parts that perform the same functions as those of the conventional example shown in FIG.

In this embodiment, an example will be described in which the cross section of the circumferential reflecting surface of the gyro main body 1 is a part of a circle (quadratic curve) (FIG. 2).

In Figure 2, a ₁ is the outer circumference of the cylinder, l ₁ is the central axis of the cylinder, r ₁ is the radius of curvature of the circle presented by the outer circumference a ₁ , and f ₁ is the focal length of the light reflected by the part a ₁ . . At this time, if the dimensions are set in a relationship such as r ₁ =2f ₁ , the focus will be on opposite circumferences in a homogeneous medium.

FIG. 3 is a diagram showing another embodiment of the gyro body used in the cylindrical laser gyro according to the present invention.

In this embodiment, the circumferential reflecting surface of the gyro main body 1 has a parabolic cross section. In the case of a paraboloid, the focal length f ₂ is determined so that the outer peripheral portion a ₂ becomes a paraboloid so that the image is formed on the parabolic reflection surface at the opposite position of the medium.

FIG. 4 is a diagram showing still another embodiment of the gyro body used in the cylindrical laser gyro according to the present invention.

The same idea can be applied to a polygon formed by a combination of straight lines or other quadratic curves, and the shape of the outer peripheral reflective surface may be selected so that the image is formed on the opposing surface.

As a result, the reflected light generated on a certain surface is condensed onto the opposing surface, and the reflected light becomes parallel light again, successively reaching near the opposing surface and repeating reflection.

Strictly speaking, these multiple reflected lights do not pass through the center of the gyroscope body 1, but instead pass as a chord shorter than its diameter, so they do not completely coincide with the focal point on the opposing surface, but they do not pass through the center of the gyroscope body 1, but at an approximate position. By concentrating the light on the light, a practically sufficient effect can be obtained.

(Effects of the Invention) As explained in detail above, according to the present invention,
Since the outer circumferential surface of the cylinder is processed to form a confocal mirror of the gyro body, the inconvenience of the beam diameter expanding infinitely even after repeated reflections is eliminated.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a cylindrical laser gyro according to the present invention, and FIG. 2 is a diagram showing an embodiment of a gyro body used in the cylindrical laser gyro according to the present invention. FIG. 3 is a diagram showing another embodiment of the gyro body used in the cylindrical laser gyro according to the present invention. FIG. 4 is a diagram showing still another embodiment of the gyro body used in the cylindrical laser gyro according to the present invention. FIG. 5 is a schematic diagram for explaining the principle of the Sagnac interferometer. FIG. 6 is a perspective view showing a conventional example of a cylindrical laser gyro. FIG. 7 is a schematic diagram showing an example of an optical path within the gyro body. 1... Gyro body, 2... Beam splitter, 3... Laser light source, 4... Clockwise emission light detector, 5... Counterclockwise emission light detector, 6... Arithmetic unit,
a ₁ to a ₃ ...outer peripheral portion of the cylinder, l ₁ to _{l 3} ... central axis of the cylinder, r ₁ to r ₃ ... radius of curvature of the circle exhibited by the outer peripheral portion a ₁ to a ₃ , f ₁ to f ₃ ...The focal length of the reflected light from _a1 to _a3 .

Claims (1)

[Scope of Claims] 1. A gyro main body having a cylindrical optical reflection surface and a laser beam input and output surface provided on the outer periphery of a transparent optical material, and a beam splitter disposed corresponding to the input and output surfaces. a laser oscillator that projects a laser beam clockwise and counterclockwise into the gyro body via the beam splitter; and a laser beam reflected and rotated clockwise within the gyro body and emitted. In a cylindrical laser gyroscope consisting of a detector that detects the phase difference of laser beams emitted after being reflected many times in a counterclockwise direction, the outer peripheral reflective surface of the gyroscope body is a concave surface facing the central axis, and its focal length is: A cylindrical laser gyroscope characterized in that the distance is approximately equal to the distance to the next outer peripheral reflective surface that the reflected light of the laser light reaches. 2. The cylindrical laser gyro according to claim 1, wherein the outer peripheral reflective surface of the gyro main body has a cross-sectional shape including a central axis that is a quadratic curve, a straight line, or a combination of quadratic curves.