JPH054619B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an optical power meter, and more specifically, to reducing measurement errors due to uneven sensitivity of photoelectric conversion elements.

(Prior Art) FIG. 4 is a configuration explanatory diagram showing an example of an optical power meter that has been put into practical use. In Figure 4,
Reference numeral 1 denotes a sensor head, in which a photoelectric conversion element 2 and a preamplifier 3 are provided. Reference numeral 4 denotes a main body of the apparatus, to which the sensor head 1 is attached and detached via a connector 5.

Incidentally, as the photoelectric conversion element 2 of such a sensor head 1, a quantum type element in which a PN junction is formed, such as Si, Ge, or InP, is often selected and used depending on the measurement wavelength range.

(Problem to be solved by the invention) However, such a quantum photoelectric conversion element 2
Since there are variations in the depth of the PN junction,
Depending on the irradiation position of the measurement light, sensitivity unevenness of about 3% will occur.

Such sensitivity unevenness is undesirable because it reduces measurement accuracy.

The present invention has focused on such points, and its purpose is to provide an optical power meter that can perform highly accurate measurements without being affected by sensitivity unevenness of quantum photoelectric conversion elements.

(Means for Solving the Problems) The optical power meter of the present invention includes a spectroscopic element, a means for scanning the spectroscopic element, a light restriction means for selectively passing the spectral output light, and a light restriction means for selectively passing the spectral output light. A photoelectric conversion element that converts applied spectral output light into an electrical signal.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 6 denotes a spectroscopic element that separates the wavelength of measurement light, and uses, for example, a diffraction grating. Reference numeral 7 denotes a support plate to which the spectroscopic element 6 is attached, one end of which is fixed to the rigid body 8 and the other end left open as a free end. Reference numeral 9 denotes an actuator that displaces the free end of the support plate 7, and uses, for example, a laminated piezoelectric element. Here, the support plate 7 and the actuator 9 constitute means for scanning the spectroscopic element 6. 10 is a slit through which the output light of the spectroscopic element 6 selectively passes;
Reference numeral 11 denotes a photoelectric conversion element that converts the spectral output light applied through the slit 10 into an electrical signal. The positional relationship between the slit 10 and the photoelectric conversion element 11 is fixed, and the output light from the spectroscopic element 6 that has passed through the slit 10 is applied to a certain position of the photoelectric conversion element 11. 12 is a preamplifier that amplifies the conversion signal of the photoelectric conversion element; 13 is an integral amplifier that integrates the output signal of the preamplifier 12; and 14 is a signal processing section that processes the output signal of the integral amplifier 13.

In such a configuration, the support plate 7 vibrates by driving the actuator 9, and the relative positional relationship between the spectral output wavelength of the spectroscopic element 6 and the slit 10 changes periodically in accordance with the vibration. . On the other hand, the slit 10 and the photoelectric conversion element 1
1 is fixed as described above, the spectral output wavelength of the spectroscopic element 6 is placed at a certain position of the photoelectric conversion element 11 so as to change periodically according to the vibration of the support plate 7. It will be added.

As a result, the preamplifier 12 outputs a signal according to frequency scanning as shown in FIG. It is possible to prevent uneven sensitivity from occurring due to changes in the irradiation position of the conversion element 11, and highly accurate optical power measurement can be achieved.

In the above embodiment, the support plate 7 on which the diffraction grating 6 used as a spectroscopic element is arranged is vibrated by the laminated piezoelectric element 9, and the frequency is scanned to a certain position of the photoelectric conversion element 11 through the slit 10. Although an example has been shown in which light is added, a galvanometer in which a diffraction grating 16 and a coil 17 are integrated with a crystal substrate 15 may be used as shown in FIG.
According to such a configuration, the scanning portion can be made smaller than that shown in FIG. 1, and it is suitable for mass production, and costs can be reduced.

In addition, in these configurations, by increasing the rotation angle of the diffraction element, the light applied to the photoelectric conversion element through the slit can be substantially stepped, and in combination with a synchronous rectification circuit, it is possible to measure the weak optical power. You can also do this.

Further, the spectroscopic element is not limited to a diffraction grating, and may be a spectroscopic device that utilizes an electro-optic effect, such as PLZT.

Also, pinholes may be used instead of slits.

(Effects of the Invention) As explained above, according to the present invention, it is possible to realize an optical power meter that can perform highly accurate measurements without being affected by the sensitivity unevenness of quantum photoelectric conversion elements, and has great practical effects. .

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention;
Figure 2 is an explanatory diagram of the output signal of the preamplifier in Figure 1;
FIG. 3 is a configuration explanatory diagram showing another embodiment of the present invention;
FIG. 4 is an explanatory diagram of the configuration of a conventional optical power meter. 6, 16... Diffraction element (spectroscopic element), 7... Support plate, 9... Actuator (laminated piezoelectric element), 10... Slit (light limiting means), 11...
Photoelectric conversion element, 12... preamplifier, 13... integrating amplifier, 14... signal processing section, 15... crystal substrate, 17... coil.

Claims (1)

[Claims] 1. A spectroscopic element, a means for scanning the spectroscopic element, a light restriction means for selectively passing the spectral output light, and a spectral output light applied via the light restriction means for converting into an electrical signal. An optical power meter comprising: a photoelectric conversion element;