Low noise pulsed light source utilizing laser diode and voltage detector device utilizing same low noise pulsed light source

A voltage detector device comprising:

• a) a low noise pulsed light source having:
• i) a laser diode for emitting a repetitive pulsed light, said pulse light having a predetermined intensity,
• ii) means for driving said laser diode, said driving means supplying at least one of a bias current and a pulse signal to said laser diode,
• iii) a photodetector for detecting part of the pulsed light emitted from said laser diode, and
• iv) a modulating means for modulating at least one of said bias current and an amplitude of said pulse signal, said modulating means modulating said bias current and said amplitude according to an output signal from said photodetector over a wide frequency band such that the intensity of said pulsed light is kept unchanged and any noise superimposed on said predetermined intensity of said pulsed light is lowered;
• b) an electrooptic material adapted to be positioned at a predetermined portion of an object to be measured and having a refractive index which is varied by a voltage, said electrooptic material being positioned at a predetermined location in an optical probe;
• c) reflecting means provided at a tip end of said electrooptic material for reflecting said pulsed light incident upon said optical probe along a central axis of said optical probe;
• and
• d) a transparent electrode located on an opposite side of said electrooptic material from said reflecting means.

A voltage detector device which utilizes an electrooptic material having a refraction index varied by applied voltages on an object comprising:

• a) a low noise pulsed light source having:
• i) a laser diode for emitting a repetitive pulsed light, said repetitive pulsed light having a predetermined intensity,
• ii) means for driving said laser diode, said driving means supplying at least one of a bias current and a pulse signal to said laser diode,
• iii) a photodetector for detecting part of the pulsed light emitted from said laser diode, and
• iv) a modulating means for modulating at least one of said bias current and an amplitude of said pulse signal, said modulating means modulating said bias current and said amplitude according to an output signal from said photodetector over a wide frequency band such that the predetermined intensity of said pulsed light is kept unchanged and any noise superimposed on said predetermined intensity of said pulsed light is lowered;
• b) a electrooptic material being positioned to cover a plurality of measurement positions of the object from which voltages are to be detected;
• c) means for directing said pulsed light from said low noise pulsed light source to enter respective portions of the electrooptic material corresponding to the plurality of measurement positions of the object;
• and
• d) means for driving said directing means to scan an optical beam from the low noise pulsed light source to the respective portions of the electrooptic material, whereby voltages of the measurement positions of the object are detected by changes in polarization states of light emanating from said respective portions of the electrooptic material.