Optics: measuring and testing – Standard
Patent
1988-11-29
1990-05-22
McGraw, Vincent P.
Optics: measuring and testing
Standard
250205, 356 731, 356218, G01J 108, G01J 110
Patent
active
049272667
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an optical signal generating apparatus and, more particularly, to an optical signal generating apparatus for outputting optical power equivalent to an externally set optical power output level set value and an optical power meter calibrating system using the same.
BACKGROUND ART
Recently, along with development of an optical communication system, middle/small-capacity transmission systems from a public communication system to an optical LAN (Local Area Network) system used in a private enterprise or the like have been increasingly put into practical use. Therefore, a field of optical measuring instrument is expected to be developed in consideration of the above situation.
A stabilized light source used in such a system is conventionally designed to satisfy optical output stability to cope with an application such as optical loss measurement or a fusing light source for an optical fiber fusion splice. However, a demand has arisen for an optical signal generator capable of varying an output power level and guaranteeing output level accuracy in order to respond to various needs as a light source.
On the other hand, optical power meters have been widely used along with recent rapid development of an optical industry, so that each user has a considerable number of optical power meters. In such a situation, a demand has arisen for maintaining accuracy of an optical power meter, i.e., accurately measuring a value of optical power with high reproducibility. Therefore, calibration of an optical power meter has attracted a great deal of attention.
Conventionally, calibration of an optical power meter is entrusted to a manufacturer of the meter, or if a traceability system is established in a company holding the meter, calibration is performed in a calibration department of the system. If calibration is entrusted to the manufacturer, however, a long time period and a transportation cost of an instrument are necessary for calibration, resulting in inconveniences. On the contrary, if calibration is performed using a standard in the company holding the meter, large scale equipment must be installed in order to maintain the standard. Currently, however, not all companies can have their own calibrating equipment.
An optical signal generating apparatus introduced in "The Anritsu Technical", No. 53, Mar. 1987, PP. 26 to 32 (issued by ANRITSU CO., LTD. of Japan) as an example of the above conventional optical signal generators adopts a circuit arrangement as shown in FIG. 1. That is, in FIG. 1, beam emitted from a light-emitting element, e.g., laser diode 1 is input to beam splitter 3 through continuous optical attenuating element 2. The beam passing through splitter 3 is attenuated by step optical attenuating element 4 to be a desired optical power level set value externally set by optical level setting circuit 9 to be described later. The output beam attenuated to be the predetermined value by element 4 is input to output fiber 5 and output from an output terminal, e.g., optical receptacle 6.
Meanwhile, beam split by splitter 3 is received by photodetector 7 and then converted into an electrical signal proportional to a received light level by O/E (Optical/Electrical converting) amplifier 21. The electrical signal is input as monitor output information to motor driver 11, and set information from D/A converter 10 is compared with the monitor output information by driver 11. As a result of comparison, driver 11 outputs a control signal to motor 12. Then, motor 12 for varying an attenuation amount of continuous optical attenuating element 2 operates to perform a power fine adjustment of the output beam from receptacle 6, and an optical power level equivalent to the set value set by setting circuit 9 is output.
Converter 13, driver 14 and motor 15 constitute a control circuit for changing the attenuation amount of step optical attenuating element 4 stepwise, and the set level value set by setting circuit 9 is displayed on display 20.
The beam emitted from laser diode 1 is r
REFERENCES:
patent: 4378490 (1983-03-01), Luigi
Tayuki Toshiharu and Two Others (Authors) "Kogakuteki Sokutei Handbook" Jul. 25, 1981, p. 416.
"The Anritsu Technical" No. 53, Mar. 1987, pp. 26 to 32.
Ito Kaoru
Nishida Yutaka
Ozaki Toshiyuki
Sugiura Itsuo
Anritsu Corporation
McGraw Vincent P.
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