JP2792129B2 - Optical angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention receives an optical signal transmitted from an optical transmission unit at an optical reception unit and transmits the optical signal at an angle opposite to the optical transmission unit, that is, transmitted from the optical transmission unit. The present invention relates to a device for detecting a rotation angle of a light receiving unit in a plane orthogonal to an optical axis of light to be transmitted.

[Conventional technology]

Conventionally, this type of optical angle detection device outputs a light beam from an optical transmission unit, receives the light beam at an optical reception unit, and measures the intensity distribution and the like of the received light to obtain an optical angle. It is configured to detect the beam direction, in other words, the angle at which the optical receiving unit faces the optical transmitting unit. In this case, a configuration in which the light beam direction is measured by mechanical means is also employed.

[Problems to be Solved by the Invention] The above-described conventional detection device measures the angle by measuring the direction in which the light beam is input to the light receiving unit, and therefore detects the distance between the light transmitting unit and the light receiving unit. Is large, it is necessary to detect a small angle. For this reason, there is a problem in that extremely high accuracy is required for the angle detection in the light receiving unit, the configuration of the detection device is complicated, or a high technology is required for the detection operation.

An object of the present invention is to provide an apparatus that can easily and accurately detect an angle even when a distance between an optical transmitting unit and an optical receiving unit is large.

[Means for solving the problem]

The optical angle detection device according to the present invention is configured such that light output from the light transmitting unit is received by the light receiving unit, and the facing angle of the light receiving unit with respect to the light transmitting unit is detected based on the received signal. ing.

Here, the light transmission unit outputs a non-polarized light signal,
A modulator for modulating the non-polarized optical signal and adding a synchronization signal to the optical signal; and a polarization unit for polarizing the modulated non-polarized optical signal and periodically changing the polarization direction. .

Further, the optical receiving unit includes an analyzing unit that receives the optical signal from the optical transmitting unit in a fixed polarization direction, detects a synchronization signal and a polarization cycle from the received signal, and determines the synchronization signal and the polarization cycle. And an arithmetic processing unit for calculating a phase difference of the optical signal from the optical signal to calculate an angle with respect to the optical transmitting unit.

[Action]

In this configuration, the synchronization signal is included in the non-polarized optical signal, and the optical signal is output as periodically changed polarization. Further, by detecting this light, calculating the phase difference of the optical signal from the periodic signal and the polarization period, and calculating the angle with respect to the optical transmission unit, it is possible to detect the facing angle between the two.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.
In the figure, reference numeral 1 denotes an optical transmitting unit, and 2 denotes an optical receiving unit. The optical receiving unit 2 receives light output from the optical transmitting unit 1, and the angle of opposition of the optical receiving unit 2 to the optical transmitting unit 1, ie, light The rotation angle of the optical receiver 2 in a plane orthogonal to the optical axis of the light transmitted from the transmitter 1 is detected.

The optical transmitter 1 has a non-polarized light source 11 for outputting a non-polarized optical signal. The non-polarized optical signal is modulated by a modulator 12 at a frequency f ₁ (H _Z ), and The synchronization pulse P is inserted at an interval of / f ₂ (second). Thus, the optical signal output from the unpolarized light source 11 is as shown in FIG. Note that f ₁ ≫f ₂ is set.

The modulated optical signal output from the unpolarized light source 11 is
The light is branched by an optical path constituted by the half mirror 14, a part of which is polarized by the polarizer 13, and the other is passed as it is. Then, the two are combined by the half mirror 14 and output as a light beam X.

Further, a rotator 15 is attached to the polarizer 13, and the rotator 15 corresponds to a synchronization pulse from the modulator 12 within a range of −45 degrees to +135 degrees with respect to the rotation direction from the reference position. It is rotated fast. The rotational speed is f _2/2 (times / second). As a result, the light beam X output from the light output unit 1 has a waveform shown in FIG.

On the other hand, the light receiving section 2 has a light receiving lens 21, an analyzer 22, and an optical receiver 23, and outputs an electric signal corresponding to the received light beam X. Then, the electric signal is input to the arithmetic processing unit 24, where the angle of the light receiving unit 2 with respect to the light transmitting unit 1 is detected. That is, the arithmetic processing unit 24 detects a synchronization pulse in the synchronization pulse detector 25 from the output signal of the optical receiver 23, and after passing through a low-pass filter 26, compares the synchronization pulse with a reference level in a comparator 27. A period is detected. Then, the synchronization pulse and the polarization cycle are input to the calculator 28, where necessary calculations are performed, and the angle of the optical receiver 2 is detected.

This will be described in detail. Now, the polarizer 13 of the optical transmission unit 1 will be described.
And the position of the analyzer 22 of the optical receiver 2 are directly opposite, the output signal of the optical receiver 23 is a polarizer that rotates at a constant speed.
FIG. 2 (b) shows the relationship between 13 and the fixed analyzer 22.
Is received as an electrical signal as it is.

However, when the analyzer 22 has an angle shift with respect to the polarizer 13, the output signal of the optical receiver 23 becomes as shown in FIG. 2 (c) due to the shift in both polarization directions. Then, based on this output signal, the synchronization pulse detector 25 detects the synchronization pulse P as shown in FIG. 2 (d), and the comparator 27 shows the envelope as shown by the envelope in FIG. 2 (c). The polarization period is detected, and the periodic signal shown in FIG. These signals are compared, and the time difference t between the rises of the two, that is, the phase difference of the polarization cycle between the light beam X and the received light signal is measured by the calculator 28.
By performing the calculation using f ₁ and f _2, it is possible to detect the angle shift of the analyzer 22 with respect to the polarizer 13, that is, the angle at which the light receiving unit 2 faces the light transmitting unit 1.

Therefore, in this detection device, the angle can be detected without detecting the direction of the light beam, and a mechanical structure for detecting the direction of the light beam is not required. In addition, even when the distance between the optical transmitting unit 1 and the optical receiving unit 2 is large, it is possible to perform the detection with high accuracy.

〔The invention's effect〕

As described above, the present invention includes a synchronization signal included in an unpolarized optical signal, and outputs the optical signal as a periodically changed polarization. Since the rotation angle of the optical receiver relative to the optical transmitter in the plane orthogonal to the optical axis of the light transmitted from the optical transmitter is calculated by calculating the phase difference of the optical signal from The rotation angle can be detected without using
Eliminates the need for a mechanical configuration to detect the light beam direction,
In addition, even when the distance between the light transmitting unit and the light receiving unit is large, the rotation angle can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 (a) to 2 (e) are signal waveform diagrams of respective parts a to e of FIG. 1 ... light transmitting section, 2 ... light receiving section, 11 ... non-polarized light source,
12 ... Modulator, 13 ... Polarizer, 14 ... Half mirror, 15
... Rotator, 21 ... Lens, 22 ... Analyzer, 23 ... Optical receiver, 24 ... Calculation processing unit, 25 ... Synchronous pulse detector, 26
…… Low-pass filter, 27… Comparator, 28 …… Calculator.

Claims (1)

(57) [Claims] An optical receiver receives light output from an optical transmitter and receives the light in a plane orthogonal to the optical axis of the light transmitted from the optical transmitter based on the received signal. In an apparatus for detecting an angle of a rotation direction of a receiving unit, the optical transmitting unit outputs a non-polarized optical signal, a modulator that modulates the unpolarized optical signal and adds a synchronization signal to the optical signal, Polarizing means for polarizing the unpolarized optical signal and periodically changing the polarization direction thereof, wherein the optical receiving unit receives the optical signal from the optical transmitting unit in a fixed polarization direction. Detecting means for detecting a synchronization signal and a polarization cycle from the received signal, and obtaining a phase difference of the optical signal from the synchronization signal and the polarization cycle, and orthogonal to an optical axis of the light transmitted from the optical transmission unit. And a calculation processing unit for calculating a rotation angle of the light receiving unit in a plane to be rotated Optical angle detection apparatus according to claim and.