Frequency shifter and optical displacement measurement apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorsMakoto Takamiya, Hidejiro Kadowaki
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Abstract
A frequency shifter for modulating the frequency of an incident light beam is disclosed. This frequency shifter includes an electro-optic crystal portion to be arranged at an incident position, an electrode arranged on the electro-optic crystal portion, a voltage application unit for applying a voltage to the electro-optic crystal portion via the electrode, and a unit which is arranged at least at a portion of the electro-optic crystal portion to uniformize the temperature of the electro-optic crystal portion.
Claims13
A frequency shifter for modulating a frequency of an incident light beam, said shifter comprising:
- an electro-optic crystal portion to be arranged at an incident position;
- an electrode arranged on said electro-optic crystal portion;
- voltage application means for applying a voltage to said electro-optic crystal portion via said electrode;
- and
- means, arranged at least at a portion of said electro-optic crystal portion, for uniformizing a temperature of said electro-optic crystal portion, wherein
- said means for uniformizing the temperature is arranged over portions, of said electro-optic crystal portion, on which two light beams are respectively incident.
An apparatus for optically detecting displacement information of an object, said apparatus comprising:
- light source means for emitting at least one light beam;
- a frequency shifter for modulating a frequency of at least one light beam emitted from said light source means, said frequency shifter including:
- i) an electro-optic crystal portion to be arranged at an incident position,
- ii) an electrode arranged on said electro-optic crystal portion,
- iii) voltage application means for applying a voltage to said electro-optic crystal portion via said electrode, and
- iv) means, arranged at least at a portion of said electro-optic crystal portion, for uniformizing a temperature of said electro-optic crystal portion;
- and
- a photodetecting portion for detecting light from the object irradiated with at least one light beam frequency-modulated by said frequency shifter, wherein
- said light source means emits two light beams, said frequency shifter causes the two light beams to be incident on said electro-optic crystal portion and modulates at least one of the two light beams, and said photodetecting portion detects light from the object irradiated with the two light beams.
A frequency shifter for modulating a frequency of an incident light beam, said shifter comprising:
- an electro-optic crystal portion to be arranged at an incident position, said electro-optic crystal portion having two electro-optic crystals in areas through which two incident light beams are respectively transmitted, and said two electro-optic crystals having crystallographic axes arranged in opposite directions with respect to an axis perpendicular to a direction of arrangement of said two electro-optic crystals;
- an electrode arranged on said electro-optic crystal portion to apply voltages to said two electro-optic crystals in the same direction;
- and
- voltage application means for applying a voltage to said electro-optic crystal portion via said electrode.
A frequency shifter for modulating a frequency of an incident light beam, said shifter comprising:
- an electro-optic crystal portion to be arranged at an incident position, said electro-optic crystal portion having two electro-optic crystals in areas through which two incident light beams are respectively transmitted, and said two electro-optic crystals having crystallographic axes arranged in opposite directions;
- an electrode arranged on said electro-optic crystal portion to apply voltages to said two electro-optic crystals in the same direction;
- voltage application means for applying a voltage to said electro-optic crystal portion via said electrode;
- and
- means, arranged at least at a portion of said electro-optic crystal portion, for uniformizing a temperature of said electro-optic crystal portion.
An apparatus for optically detecting displacement information of an object, said apparatus comprising:
- light source means for emitting at least one light beam;
- a frequency shifter for modulating a frequency of at least one light beam emitted from said light source means, said frequency shifter including:
- i) an electro-optic crystal portion to be arranged at an incident position, said electro-optic crystal portion having two electro-optic crystals in areas through which two incident light beams are respectively transmitted, and said two electro-optic crystals having crystallographic axes arranged in opposite directions with respect to an axis perpendicular to a direction of arrangement of said two electro-optic crystals,
- ii) an electrode arranged on said electro-optic crystal portion to apply voltages to said two electro-optic crystals in the same direction, and
- iii) voltage application means for applying a voltage to said electro-optic crystal portion via said electrode;
- and
- a photodetecting portion for detecting light from the object irradiated with at least one light beam frequency-modulated by said frequency shifter, thereby detecting displacement information of the object.
Dependencies are inferred from the claim text.