JPH0387670A - Device for measuring electric field by optical system - Google Patents

Abstract

PURPOSE:To facilitate the assembly, to simplify the constitution and to improve the S/N by forming a mirror consisting of a reflection film on the plate surface of the emission side of a wavelength plate, in the electric field measuring device of a reflection type. CONSTITUTION:A wavelength plate 21 is formed like a plate, for instance, by cutting a crystal of quartz at a prescribed angle, and on the plate surface of the emission side of this wavelength plate 21, a mirror 22 of a high reflection factor consisting of a thin film of a metal (example: Al) is formed by vacuum vapor deposition or spattering. This wavelength plate 21 is used by placing it on the emission side of an electro-optical crystal and irradiated with a light beam from a light source through a polarization beam splitter and a polarizer. Subsequently, an emitted light of the electro-optical crystal is reflected by the mirror 22 formed on the plate surface of the emission side of the wavelength plate 21, allowed to transmit through the electro-optical crystal again, separated by a polarization beam splitter, led to a photodetector and converted to an electric signal. In such a way, by forming integrally the wavelength plate 21 and the mirror 22, an optical alignment becomes unnecessary, the assembly is facilitated, and also, the constitution can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an optical electric field measuring device that measures an electric field using the Bockels effect of an electro-optic crystal.

(Technical background of the invention and its problems) Generally, when an electric field is applied to a substance, its optical properties change. This phenomenon is widely called the electro-optic effect, and the Bockels effect, Kerr effect, etc. are well known. in this case,
The refractive index n of the crystal is given by the following equation.

n=no+aE+bE2+ --- where no: refractive index before electric field application E: applied electric field Here, the first-order coefficient a of the electric field E is called the Bockels coefficient, and the second-order coefficient is called the Kerr coefficient.

Then, an electric field created by interweaving a medium with such an electro-optic effect (hereinafter referred to as an electro-optic crystal) and an optical fiber,
Voltage measurement devices have been developed that utilize the Bockels effect in which the refractive index of an electro-optic crystal is proportional to the first order term of the electric field.

In other words, the phase change between ordinary and extraordinary rays in a birefringent electro-optic crystal utilizes the fact that the polarization plane of incident linearly polarized light rotates by a certain angle while passing through this crystal medium. . For example, incident circularly polarized light becomes elliptically polarized light at the exit surface of the crystal.

Therefore, an electro-optic crystal is placed in the electric field to be measured, and the change in birefringence induced in the crystal as the electric field changes is measured using a polarizer, analyzer, etc. ! Changes in the electric field can be measured by detecting changes in the signal strength.

Claims (1)

[Claims] A reflection-type electric field measuring device that measures an electric field from an optical change due to the Bockels effect of a light beam transmitted through an electro-optic crystal, comprising: a light source; and light from the light source is transmitted through a beam splitter and a polarizer. an electro-optic crystal that is incident on the electro-optic crystal, an electrode provided on the electro-optic crystal that applies an electric field to be measured, and a light that has passed through the electro-optic crystal that is reflected back toward the light source via a wave plate and an analyzer. a mirror; and an electric field measurement unit that separates the light reflected by the mirror and transmitted through the electro-optic crystal by the beam splitter and measures the electric field from optical changes, the output side plate surface of the wavelength plate An optical electric field measuring device characterized by being provided with a mirror made of a reflective film formed on.