JPH021993A - Detected light intensity control system - Google Patents

Abstract

PURPOSE:To enable the construction of a short range optical system without using an optical attenuator of fixed attenuation and to eliminate the necessity of the replacement of the optical attenuator, which is needed in a conventional one, even if the optical system is moved by a method wherein a photoelectric power limiting means is made to control an photoelectric power of an optical signal corresponding to the detected result by a light intensity detecting means. CONSTITUTION:A photoelectric power limiting section 3, possessed of a liquid crystal sandwiched in between electrodes, is provided to the front of a photodetecting element 1, which is connected with a photodetecting element detected light intensity detecting circuit 2. The detecting circuit 2 detects the light intensity of a light signal input at the front of the photoelectric limiting section 3. The detecting circuit 2 is previously set to an adequate detected light intensity, and when the detected light intensity is deviated from the adequate detected light intensity, a control signal corresponding to the deviation is sent to the photoelectric power limiting section 3. The photoelectric power limiting section 3 applies a voltage, which corresponds to the control signal, onto the electrodes that have sandwiched to liquid crystal in between them. Thereby, the liquid crystal changes in transmittance to a photoelectric power. By these processes, an optical signal of adequate intensity is inputted into the photodetecting element 1. That is, a light intensity detected by the photodetecting element 1 becomes adequate in value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for limiting the total adjustment of received light intensity in an optical system.

[Conventional technology] Conventionally, when constructing a complete optical system, the light intensity received by the light receiving element is calculated in advance by taking into account the optical output power of one light emitting element, the loss of the optical cable, the distance, etc.

When the received light intensity is equal to or higher than a preset specified value, an optical attenuator with a fixed amount of attenuation is inserted in front of the light receiving element to keep the received light intensity within the specified value.

[Problem that the invention seeks to solve]

In the case of the above-mentioned conventional light receiving light intensity limiting method, especially in short-distance source systems, it is necessary to insert an optical attenuator, which not only increases cost but also reduces reliability.

Furthermore, when relocating the optical system, there is a problem in that the optical attenuator must be changed and a new optical attenuator must be inserted in response to changes in the received light intensity.

[Means for solving problems]

According to the present invention, the detection means detects the difference between the luminous intensity of the optical signal received by the light receiving element and the preset set luminous intensity, and the detection means is disposed on the light receiving side of the light receiving element, and the detection means is disposed on the light receiving side of the light receiving element, What is the optical power limiting means that fully adjusts the optical power of the optical signal?
There is obtained a received light intensity limiting method, characterized in that the light distribution power limiting means adjusts the optical power of the optical signal according to the detection result by the detecting means.

〔Example〕

Next, the present invention will be explained with reference to examples.

Referring to FIG. 1, an optical power limiting section 3 comprising a liquid crystal sandwiched between electrodes is disposed on the front surface of a light receiving element 1, and a light receiving element received light intensity detection circuit 2 is installed in this optical power limiting section 3. It is connected. This detection circuit 2 is connected to the front surface of the optical power limiter 3 (
The luminous intensity of the optical signal is detected at the left side in the figure. The detection circuit 2 has an appropriate received light intensity set in advance.

If the detected received light intensity deviates from this appropriate received light intensity.

A control signal corresponding to the deviation from the proper received light intensity is sent to the optical power limiting section 6. The optical power limiting unit 6
When receiving the N signal, a voltage corresponding to this control signal is applied to the electrodes sandwiching the liquid crystal. This changes the color tone of the liquid crystal.

That is, the transmittance of the optical signal power of the liquid crystal changes. As a result, a light signal with an appropriate luminous intensity is manually applied to the light receiving element 1. In other words, the light intensity received by the light receiving element 1 becomes an appropriate value.

〔Effect of the invention〕

As explained above, 1. Since the present invention automatically controls the light intensity received by the light receiving element to be appropriate, it is possible to construct a short-range optical system without using an optical attenuator with a fixed attenuation amount. .

Even when the optical system is relocated, there is no need to replace the optical attenuator as in the conventional case. Furthermore, since a fixed attenuation (one optical attenuator) is not used, there is no need to increase the light intensity that can be received by the light receiving element.

[Brief explanation of the drawing]

FIG. 1 is a diagram for fully explaining one embodiment of the present invention. 1... Light receiving element, 2... Light receiving element receiving light intensity detection absorption Route 3... Optical power distribution department. Figure 1

Claims (1)

[Claims] 1. a detection means for detecting a deviation between the luminous intensity of the optical signal received by the light receiving element and a preset setting luminous intensity, and an optical signal disposed on the light receiving side of the light receiving element and input to the light receiving element; and an optical power limiting means for adjusting the optical power of the optical signal, and the optical power limiting means adjusts the optical power of the optical signal according to a detection result by the detecting means. method.