Physical quantity measurement apparatus and instrument therefor

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means;
• and
• means for calculating pressure acting on the object on the basis of the quantity of displacement of the object calculated by said displacement calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means;
• and
• means for calculating a pressure difference acting on the object on the basis of the quantity of displacement of the object calculated by said displacement calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means;
• and
• means for calculating an acceleration acting on the object on the basis of the quantity of displacement of the object calculated by said displacement calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two by the wavelengths;
• a first polarization beam splitter by which reflected light of one wavelength extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for converting the respective changes of intensity of light beams extracted by said first and second polarization beam splitters into electric signals and for obtaining average values of maximum values and minimum values of the electric signals, respectively;
• means for generating electric signals obtained by subtracting the average values obtained by said converting means from the electric signals of said converting means, respectively;
• means for detecting voltages applied to said electro-optical crystal in a moment when the electric signals generated by said generating means cross at a zero point and for obtaining the applied voltages and the difference between the applied voltages;
• and
• means for calculating the physical quantity acting on the object on the basis of the applied voltage difference obtained by said detecting means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators on the basis of a phase component .DELTA..phi. determined by A.multidot.sin.omega.t wherein an amplitude A satisfies zeroth-order Bessel function J.sub.0 (A)=0 and a phase .omega. represents the frequency of said voltage;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for converting the respective changes of intensity of light beams extracted by said first and second polarization beam splitters into electric signals;
• means for detecting voltages applied to said electro-optical crystal in a moment when the electric signals obtained by said converting means cross at a zero point and for obtaining the applied voltages and the difference between the applied voltages;
• and
• means for calculating the physical quantity acting on the object on the basis of the applied voltage difference obtained by said detecting means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said half mirror is made to go out to the object side and through which reflected light from the object side is made to go out to the half-mirror side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the half-mirror side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for obtaining the phase difference between light beams extracted by said first and second polarization beam splitters;
• and
• means for calculating the physical quantity acting on the object on the basis of the phase difference obtained by said obtaining means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• an object which is transformed by suffering pressure;
• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• and
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• an object which is transformed by suffering pressure;
• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means;
• and
• means for calculating pressure acting on the object on the basis of the quantity of displacement of the object calculated by said calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• an object which is transformed by suffering pressure from its opposite sides;
• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said detecting means;
• and
• means for calculating a pressure difference acting on the object on the basis of the quantity of displacement of the object calculated by said displacement calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• a plurality of objects which are transformed by suffering pressure from their opposite sides;
• two laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a half mirror for transmitting the polarized light beams emitted from said laser oscillators;
• an electro-optical crystal driven by a voltage for modulating the phase of light emitted from said laser oscillators;
• a polarization plane conserving optical fiber through which light given from said electro-optical crystal is made to go out to the object side of a selected one of said plurality of objects by means of an optical switch and through which reflected light from the object side is made to go out to the electro-optical crystal side;
• a 1/4 wavelength plate located between the object and the object side end portion of said polarization plane conserving optical fiber;
• a beam splitter by which reflected light from the electro-optical crystal side end portion of said polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelength extracted by said beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said beam splitter is split into two by polarization planes;
• means for detecting voltages, applied to said electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and the difference between the applied voltages;
• means for calculating the quantity of displacement of the object on the basis of the applied voltage difference obtained by said detecting means;
• and
• means for calculating a pressure difference acting on the object on the basis of the quantity of displacement of the object calculated by said displacement calculating means.

An apparatus for optically measuring a physical quantity of an object, which comprises:

• an object which is transformed by suffering pressure;
• two first laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a first half mirror for transmitting the polarized light beams emitted from said first laser oscillators;
• a first electro-optical crystal driven by a voltage for modulating the phase of light emitted from said first laser oscillators;
• a first polarization plane conserving optical fiber through which light given from said first electro-optical crystal is made to go out to a transformable side of the object and through which reflected light from the object side is made to go out to the first electro-optical crystal side;
• a first 1/4 wavelength plate located between the object and the object side end portion of said first polarization plane conserving optical fiber;
• a first beam splitter by which reflected light from the first electro-optical crystal side end portion of said first polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a first polarization beam splitter by which reflected light of one of the wavelengths extracted by said first beam splitter is split into two by polarization planes;
• a second polarization beam splitter by which reflected light of the other wavelength extracted by said first beam splitter is split into two by polarization planes;
• first means for detecting voltages, applied to said first electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said first and second polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• first displacement quantity calculating means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said first means;
• two second laser oscillators for respectively emitting linearly polarized light beams having wavelengths different from each other;
• a second half mirror for transmitting the polarized light beams emitted from said second laser oscillators;
• a second electro-optical crystal driven by a voltage for modulating the phase of light emitted from said second laser oscillators;
• a second polarization plane conserving optical fiber through which light given from said second electro-optical crystal is made to go out to a transformable side of the object and through which reflected light from the object side is made to go out to the second electro-optical crystal side;
• a second 1/4 wavelength plate located between the object and the object side end portion of said first polarization plane conserving optical fiber;
• a second beam splitter by which reflected light from the first electro-optical crystal side end portion of said second polarization plane conserving optical fiber is split into two correspondingly to the wavelengths;
• a third polarization beam splitter by which reflected light of one of the wavelengths extracted by said second beam splitter is split into two by polarization planes;
• a fourth polarization beam splitter by which reflected light of the other wavelength extracted by said second beam splitter is split into two by polarization planes;
• second means for detecting voltages, applied to said second electro-optical crystal, at which one of a maximum value, a minimum value, and an average value of a maximum value and a minimum value of intensity of light beams extracted by said third and fourth polarization beam splitters is obtained and for obtaining the applied voltages and a difference between said applied voltages;
• second displacement quantity calculating means for calculating the quantity of displacement of the object on the basis of the difference between said applied voltages obtained by said second calculating means;
• and
• third means for calculating pressure acting on said object on the basis of calculated values from said first and second displacement quantity calculating means.