JPH0437332A - Optical space transmitter - Google Patents

Abstract

PURPOSE:To attain optical axis adjustment simply and inexpensively by making an optical axis of a laser beam transmitted from a half mirror with that of a reflected visual light beam so as to confirm the light transmission state of the visual light beam. CONSTITUTION:A laser beam and a visual light made incident in a lens 23 are collimated and outputted to a light receiver side device B. The light beam made incident in the device B is given to a lens 25 and the laser beam is focused to a sensor of a signal receiver 27 for optical space transmission through a half mirror 26 of the next stage. On the other hand, the visual light beam in the incident light is reflected in the incident face of the half mirror 26 and focused to the sensor of a visual light display device 28. Since the visual light quantity made incident in the display device 28 is proportional to the incident luminous quantity of the laser beam for signal transmission, the light receiver side device B is moved so that the luminous quantity made incident in the display device 28 is maximized and the optical axis of the sender and that of the receiver are adjusted so as to align with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical space transmission device that performs optical communication by space transmission, and particularly relates to the configuration of an optical axis adjustment device of a light transmitter/receiver in the optical space transmission device. .

(Prior art) The frequency band of light is significantly larger than that of microwave frequencies, making it possible to carry out large-capacity communications, and optical communication will be indispensable in processing the large amount of transmitted information that will increase in the future. It becomes.

The above-mentioned optical communications include an optical space transmission method using spatial propagation, an optical cable transmission method using an optical cable, and an optical lens guide method. Among these various methods, the optical space transmission method has a simple equipment configuration and is therefore short-distance. Application development has been progressing in recent years as a wireless communication means for

In this optical space transmission, in order to perform communication using the straightness of the light beam, it is necessary to accurately project the transmitted light onto the light receiving surface of the receiver, and the optical axis adjustment between the transmitting side and the receiving side is done in space. It is indispensable for optical communication using transmission methods.

Among the optical axis adjustment methods used in the past, the simplest method is to install a fiducial on the top of the light transmitter and the light receiver, and use the fiducial to perform visual inspection.

However, when using the conventional method as described above, there is a problem in that the price of the optical space transmission apparatus cannot be reduced because the standard for adjusting the optical axis is expensive.

A method that does not use a standard is JP-A-64-23631.
There are some that have been disclosed.

FIG. 2 is a diagram showing an outline of a communication device in spatial optical communication disclosed in Japanese Patent Application Laid-Open No. 64-23631, in which 1 is a transmitting side device and 11 is a receiving side device. ,
The transmission side device 1 includes a transmission side optical transmitter 2, a transmission signal modulator 3,
It consists of a stand 4 for fixedly holding the light transmitter, a CCD camera 5, and a monitor 6. On the other hand, the receiving side device 11 includes a receiving side light receiver 12, a receiving side demodulator 13, and a stand for holding the light receiver fixedly. 14, a CCD camera 15, a monitor 16, and a filter 17.

In the device configured in this way, the light pulse emitted from the laser diode provided in the light transmitter 2 is converted into parallel light by the lens and is sent out, and enters the light receiver 12 in the receiving side device via the filter 17. At the same time, a part of the light incident on the filter is reflected, and the light receiver 1
The reflected light is detected by the CCD camera 15 provided on the top of the photo frame 2.

Therefore, although the laser light emitted from the laser diode cannot be seen with the naked eye, it can be detected by the CCD.
The optical axis adjustment can be performed, or the laser beam is emitted from the light transmitter 2, and the reflected light reflected from the incident surface of the light receiver is transmitted to the upper part of the light transmitter 2. By detecting this with the CCD camera 5 installed in the optical receiver, it is possible to grasp the state of reflection of the emitted light on the incident surface of the light receiver, thereby making it possible to adjust the optical axis.

However, the optical space transmission device having the optical axis adjustment function as described above uses a CCD to visualize the laser beam.
Alternatively, an optical space transmission device that uses a means to reflect the light beam at the incident surface of the light receiver requires a means to reflect the emitted light to the light transmitting side, which increases the cost of the device. Two problems still existed.

(Object of the Invention) The present invention has been made in view of the conventional problems as described above, and provides an optical space transmission that can be constructed simply and inexpensively, and that allows accurate optical axis adjustment. The purpose of the present invention is to provide an optical axis adjustment device for use in.

(Summary of the Invention) In order to achieve the above object, an optical axis adjusting device according to the present invention is a space transmission device using a light beam, and at least a light transmitting side device includes a laser light source for transmitting a communication signal and a visible light source. The light-receiving device includes a visible light source for transmitting light, and a half mirror that transmits the laser light emitted from the laser light source and reflects the visible light emitted from the visible light source. A half mirror that transmits the laser beam emitted from the light transmitting side and reflects visible light, a light receiver that transmits the half mirror and receives the laser beam, and a visible mirror that detects the visible light reflected by the half mirror. By providing a photodetector, the optical axes of the laser beam emitted from the half mirror of the light transmitting side device and the visible light reflected from the half mirror are aligned, and the communication signal transmission is performed by checking the transmission state of the visible light. It is characterized by adjusting the optical axis of the laser beam, which is the medium of the laser beam.

(Example) Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 is a diagram showing a schematic configuration of an optical space transmission device according to the present invention.

In the figure, A is a light transmitting side device, B is a light receiving side device, and the light transmitting side device consists of a visible light source 20 for optical axis adjustment, a laser light source 21, a half mirror 22, and a lens 23.
- The power receiving side device is composed of a lens 25, a half mirror 26, a light receiver 27 for optical spatial transmission signals, and a visible light display 28.

Generally, as a light source for an optical space transmission device, a light source with a wavelength of about 800 nm to 1300 nm is used due to problems with transmission characteristics, and if red light with a wavelength of 660 nm is used as the visible light source 20, the half mirror
22 and 26 are used which have a characteristic of transmitting light rays having a wavelength of 800 nm or more and reflecting light rays having a wavelength of 660 nm.

When adjusting the optical axis in the optical space transmission device configured in this way, both the laser light source 21 and the visible light source 20 are activated in the light transmitting side device, and the laser light source 21 is activated.
The laser beam outputted from the mirror 1 passes through the next half mirror 22 and enters the lens 23.

On the other hand, the red light emitted from the visible light source 20 is reflected at the incident surface of the next stage half mirror 22 and enters the lens 23 along the same optical axis as the laser light.

Laser light and visible light incident on the lens are converted into parallel light beams and output to the light receiving side device.

The light beam input to the light-receiving device B enters the lens 25,
Of the incident light, the laser light passes through the next stage half mirror 26 and is focused on the sensor portion of the signal receiver 27 for optical spatial transmission.

On the other hand, the visible light rays of the incident light are reflected by the incident surface of the half mirror 26 and are focused on the sensor portion of the visible light indicator 28 .

Therefore, since the amount of visible light incident on the visible light indicator 28 is proportional to the amount of incident laser light for signal transmission,
The light-receiving device is moved so that the amount of light incident on the visible light display is maximized, and adjustments are made so that the optical axes of the transmitting and receiving devices coincide.

In other words, since the beam for optical axis adjustment and the laser beam for signal transmission are supplied from the same optical axis, the state of the optical axis can be grasped directly compared to the conventional optical axis adjustment using a standard. In addition to having a harmonic that can be used to visualize and display laser light, it is possible to detect and adjust the reflected light of laser light with a CCD. All you need is a half mirror,
It becomes possible to supply the device at a low price.

In the embodiment of the present invention, visible light emitted from the light transmitting side is reflected and separated using a half mirror on the light receiving side.
The explanation has been made using a device that adjusts the optical axis of the laser beam by detecting the state of reception of the visible light, but when used in a short distance space transmission device, a half mirror 1 visible light detection display provided on the light receiving side is used. No particular means is required, and optical axis alignment can be achieved by aligning the light-receiving lens of the light-receiving device with the visible light beam from the light-transmitting side.

(Effects of the Invention) Since the present invention is configured and functions as described above, by adding an inexpensive device, it is possible to directly monitor and adjust the optical axis of the laser beam, which is the medium of the optical space transmission signal. In addition, when adjusting the optical axis, it is possible to easily move only the light-receiving device, so it can be used even in cases where it is difficult for people to approach the location where the light-transmitting device is installed. It exhibits a remarkable effect in easily adjusting the optical axis.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a spatial optical transmission device according to the present invention, and FIG. 2 is a diagram showing a configuration of a conventional spatial optical transmission device. A... Light transmitting side device, B... Light receiving side device 20... Visible light source, 21... Laser light source 22.26... Half mirror 23.25... Lens, 27... Light Receiver for spatial transmission signals, 28...Visible light display patent applicant Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] In a space transmission device using a light beam, at least the light transmitting side device includes a laser light source for transmitting a communication signal, a visible light source for transmitting visible light, and a device that transmits the laser light emitted from the laser light source. and a half mirror that reflects the visible light emitted from the visible light source, and in the light receiving side device, a half mirror that transmits the laser beam emitted from the light transmitting side and reflects the visible light; The laser beam emitted from the half mirror of the light transmitting device is equipped with a light receiver for receiving the laser beam transmitted through the half mirror and a visible light detector for detecting the visible light reflected by the half mirror. An optical space transmission device characterized in that the optical axis of a laser beam, which is a communication signal transmission medium, is adjusted by aligning the optical axes of visible light reflected by a mirror and checking the transmission state of the visible light.