JPH056509Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an optical power meter, and particularly to a separate type optical power meter in which a sensor head and a main body are separated.

Conventional technology In a separate optical power meter in which the sensor head and main body are separated, in order to correct the sensitivity of the light receiving element in the sensor head, a resistor (generally A semi-fixed resistor) is often built into the sensor head, and this resistor is often configured to adjust the gain of the amplifier within the main body (or the sensor head). In other words, with this configuration, any sensor head and any body can be combined within the same model, and the sensor head and body can be compatible. be.

Problems to be Solved by the Invention However, since light-receiving elements generally have spectral sensitivity characteristics, in the case of the above configuration, the optical power meter only displays the correct optical power for light of one wavelength. Therefore, in order to make it compatible with each of the multiple wavelengths of light, it may be possible to attach a table showing the spectral sensitivity characteristics for each wavelength of light to the sensor head, but in that case, the user is responsible for determining the optical power of other wavelengths. It is necessary to perform correction calculations based on the table. Also, it would be ideal to write the spectral sensitivity characteristics into a ROM and incorporate this ROM into the sensor head or main body, and automatically calculate corrections within the main body, but this would make the optical power meter bulky.
Becomes expensive.

The object of this invention is to provide a separate optical power meter that can correct the spectral sensitivity of a light receiving element in a sensor head with an extremely simple configuration.

Means for Solving Problems This invention is a separate type optical power meter in which a sensor head equipped with a light receiving element and a main body equipped with a variable gain amplifier that amplifies the signal are separated and connected by a signal line. A plurality of sensitivity correction resistors adjusted to The present invention is characterized in that it is connected via a signal line and further includes a switch for switching the plurality of resistors.

Function The sensor head has a built-in photodetector and multiple sensitivity correction resistors, and each of these is connected to the variable gain amplifier inside the main body via a separate signal line. Each of the sensitivity correction resistors can be adjusted for each wavelength of light according to the unique spectral sensitivity characteristics of the light receiving element. Since these resistors can be switched by a switch, the gain of the variable gain amplifier in the main body can be changed for each wavelength according to the value of each resistor.
In other words, the sensor head is equipped with a photodetector as well as a resistor for correcting the sensitivity for each wavelength specific to the element, so the sensitivity can be corrected for each wavelength by adjusting each resistor. For example, even if the sensor head is replaced and connected to the main body, the sensitivity will be corrected for any wavelength of light by switching the switch. It is also possible to ensure light of any wavelength, and compatibility between the sensor head and the main body can be realized for light of any wavelength.

Example In the figure, the sensor head 1 includes a light receiving element 11.
is built in, and when it receives light, it sends the received light signal to the main body 2, which is separate from the sensor head 1.
Send it via an appropriate cable, etc. Inside the main body 2, an amplifier 21, a variable gain amplifier 22, and an indicator 2 are installed.
The pointer of the indicator 23 swings in response to the received light signal, and the power of the received light is displayed.

The sensor head 1 further includes a plurality of (two in this embodiment) sensitivity correction resistors 12, 13 and a switch 14. This resistor 1
Numerals 2 and 13 are for correcting the sensitivity of the light receiving element 11 built into the sensor head 1, and are adjusted to correspond to light of different wavelengths. Switch 14 is for selecting either of these resistors 12, 13. By turning the switch 14 in either direction, the selected resistor is connected to the variable gain amplifier 22, and the gain of the variable gain amplifier 22 is determined by its resistance value. The resistance values of the resistors 12 and 13 are adjusted in advance with respect to the light receiving element 11 so that the indicator 23 indicates the correct optical power for light of different wavelengths.

Therefore, when trying to measure the optical power of light of a certain wavelength, by operating the switch 14 to select the sensitivity correction resistor for that wavelength, the spectral spectrum of the light of that wavelength of the light receiving element 11 can be adjusted. The sensitivity will be automatically corrected and the optical power will be correctly indicated by the indicator 23. In this way, the spectral sensitivity characteristics of the light-receiving element 11 can be easily corrected, although only for a limited number of lights of specific wavelengths corresponding to the number of variable resistors.

Although the resistor changeover switch 14 is provided in the sensor head 1 in the above example, it is also possible to provide the switch 14 on the main body 2 side and connect it to the resistors 12 and 13 of the sensor head 1 using a cable or the like. can. Further, the changeover switch 14 built into the sensor head 1 can be configured to be switched by remote control from the main body 2 side.

Effects of the invention In the separated optical power meter of this invention, the sensor head has a light receiving element and multiple resistors built in to correct the sensitivity for each wavelength specific to the element, and the resistors are switched by a switching circuit. With an extremely simple configuration, compatibility between the sensor head and the main body can be ensured for any of the multiple wavelengths of light.

[Brief explanation of drawings]

The figure is a block diagram of a separate optical power meter according to an embodiment of this invention. DESCRIPTION OF SYMBOLS 1... Sensor head, 2... Optical power meter main body, 11... Light receiving element, 12, 13... Sensitivity correction resistor, 14... Changeover switch, 21... Amplifier, 22... Variable gain amplifier, 23... ...Indicator.

Claims (1)

[Scope of utility model registration request] It consists of a sensor head having a light-receiving element, and a main body that is separate from the sensor head, is connected via a signal line, and is equipped with a variable gain amplifier that amplifies the signal of the light-receiving element sent via the signal line. The optical power meter includes a plurality of sensitivity correction resistors arranged in the sensor head and adjusted for each wavelength and connected to a variable gain amplifier in the main body via another signal line; An optical power meter characterized by comprising a switch for switching a plurality of resistors.