Abstract: Provided is a checking apparatus for array electrode substrate, which can check an array electrode substrate in non-contact and at high speed. A probe assembly includes a plurality of electro-optic probes arranged in the staggered relation. Since this arrangement uses a plurality of (for example, eight, sixteen, twenty, forty, etc.) small electro-optic probes, it becomes equivalent to an arrangement of an elongate electro-optic probe, thereby enabling simultaneous measurement of potentials of numerous unit electrodes. Namely, because a measurement light beam is incident into each electro-optic probe and each reflection-return light is detected by a photodector, potentials of unit electrodes in a number corresponding to the number of electro-optic probes can be simultaneously measured.

Abstract: An electric field measuring apparatus for causing an optical probe head having an electro-optic member with an electro-optic material to oppose a sample such as a semiconductor integrated circuit device and for optically measuring a voltage of an opposite portion of the sample. The electro-optic material consists of an LiTaO.sub.3 electro-optic crystal or the like, the polarization characteristics of which change depending on the electric-field strength of the sample. The electro-optic member is supported on a guide mechanism to be reciprocally movable within a predetermined stroke range in a direction of the sample. The guide mechanism is reciprocated in the direction of the sample to control the distance between the electro-optic material and the sample.

Abstract: An E-O probe for a two-dimentional voltage detecting apparatus using a fiber optic plate is provided. The fiber optic plate has a bottom face facing a measured object and a bundle of a plurality of cores separated from one another by cladding electro-optic material is attached to an end of each core at said bottom face side. A reflecting surface is provided on the bottom face side of the fiber optic plate for reflecting light back toward the side of the fiber optic plate opposite said bottom face. The refractive index of said electro-optic material varies in response to the intensity of an electric field applied to the electro-optic material. A two-dimentional voltage detecting apparatus using the E-O probe is further provided which has a high spatial resolution.

Abstract: This invention has as its object to provide a voltage measurement apparatus which has a compact probe unit, and which can perform a measurement in a non-contact manner. The voltage measurement apparatus includes detection means for detecting an electric field generated in a space by a voltage applied to the surface of a device to be measured, light-emitting means for modulating output light by superposing a detected signal obtained from the detection means on a bias current which is supplied to inductively radiate the output light, a constant current source for supplying the bias current to the light-emitting means, extraction means for extracting a signal component of the output light from the light-emitting means, and light-transmission means for guiding the output light from the light-emitting means to the extraction means, and measures the applied voltage to the surface of the device to be measured by bringing the detection means close to the device to be measured in a non-contact manner.

Abstract: An method of positioning an E-O probe applied to an apparatus for the measurement of voltage. In the first step, the relative position of the E-O probe against the magnifying optical system in the first condition of being focused the magnifying optical system on the base of the E-O probe, and the focal point difference between the focal plane of the magnifying optical system in the second condition that the E-O probe is substantially out of the optical path for observation of the surface of the device and the focal plane in the first condition are stored. The relative position and the focal point difference are fixed in the apparatus for the measurement of voltage regardless of the device to be measured.

Abstract: An electro-optic material constituting an E-O probe has a refractive index for light from a semiconductor laser, which is changed in accordance with an electric field from a device to be measured. The electro-optic effect is substantially canceled upon incidence of light from an Ar.sup.+ laser. A mechanical chopper modulates the light emitted from the Ar.sup.+ laser and causes the light to be incident on the E-O probe. A lock-in amplifier detects the polarized state of the light reflected by the E-O probe synchronized with the modulation, thereby measuring the voltage of the device.

Abstract: An E-O probe with improved spatial resolution has a light transmissive base part, an electro-optic material which is fixed to the base part and has an index of refraction which varies in response to an electrical field from a measured object, and a mirror which is fixed to the electro-optic material and reflects an incident beam penetrating the base part and the electro-optic material. The mirror is formed to be smaller than the incident beam in diameter. The electro-optic material is formed very thin.

Abstract: A system for measuring timing relationship between two signals for accurately measuring a timing relationship between signals includes an electro-optic measuring unit and a waveform storage and processing unit. The electro-optic measuring unit samples electrical signals from a device under measurement via a strobe light so as to measure the signal waveform. The electro-optic unit uses a laser diode as a light source. The waveform storage and processing unit stores the electrical signal waveforms measured by the electro-optic measuring unit in digital form. The waveform storage and processing unit also calculates a correlation between two stored electrical signal waveforms via a correlation calculation unit, and also detects a peak of the correlation to detect a timing relationship between the signals.

Abstract: To provide an E-O probe which can measure a voltage distribution in a fine region while enlarging it. A grounded, transparent electrode 2 and an electrooptic member 3 such as LiTaO.sub.3 are successively fixed to and below a support 1. There are a plurality of conical, conductive members 5a-5e arranged below a reflection film 4 in such a manner that the bottom surfaces thereof are fixed to the lower surface of the reflection film 4 and that the lower ends thereof project downward. Spaces between the plural, linear, electric needles 5a-5e become narrower toward a measured object located below them, whereby voltages in a fine region in the measured object can be guided as enlarged to the electrooptic member 3.

Abstract: A change in voltage can be sensitively detected at a local part of a measured object. A set of laser medium and E-O probe are disposed between a pair of mirrors, a first one and a second one, forming a laser resonator. A linearly polarized light is emitted from the laser medium. The polarized light enters the E-O probe, and returns after being reflected by the second mirror. When a voltage is given to the E-O probe from the measured object, depending on the voltage, a refractive index of the E-O probe is changed, the light emitted from the E-O probe is ovally polarized, and a resonance status of the laser resonator then varies. Therefore, the light intensity emitted through the partially penetrating first mirror to the outside of the laser resonator corresponds to the voltage at the measured object in the proximity of the E-O probe. Consequently, a voltage distribution on the measured object such as IC with fine structures can be two-dimensionally detected.

Abstract: Polarized light is input to an optical modulator typically consisting of an electrooptic crystal. The polarization state of the input light is changed in accordance with a voltage being applied to the optical modulator. Receiving the light output from the optical modulator, a polarization interferometer produces an interference fringe on the input surface of a photodetector such as a streak camera and a CCD line sensor. Based on an output signal of the photodetector, an analyzing device calculates a pitch and a movement distance of the interference fringe to determine the voltage being applied to the optical modulator.

Abstract: Polarized light pulses are applied to an optical modulator including an electrooptic crystal. A polarization state of the applied light is changed in accordance with a voltage of an electrical signal applied to the optical modulator. A polarization interferometer receives the light output from the optical modulator, and generates an interference fringe on the input surface of a photodetector such as a one-dimensional CCD. A processing device calculates a pitch and a movement distance of the interference fringe, based on an output signal of the photodetector, to determine the voltage. A waveform of the electrical signal is determined by sampling the electrical signal with multiple light pulses, while varying a phase relationship between the electrical signal and the light pulses.

Abstract: Young's interferometer consisting of a single slit and a double slit member, and an analyzer are arranged along the axis of light to be measured. Parallel slits of the double slit member are provided with respective polarizers whose paralyzing directions are at .+-.45.degree. to the longitudinal direction of the parallel slits. The polarizing direction of the analyzer is set in parallel with the parallel slits. The incident light passes through Young's interferometer and the analyzer to form an interference fringe, which is detected by an image detector unit. An image analyzer unit produces an intensity profile of the interference fringe and determines the polarization state of the incident light, for instance, by comparing the produced intensity profile with conceivable profiles stored in advance.

Abstract: A low noise pulsed light source utilizing a laser diode for generating a short pulsed light of a high repetitive frequency. The low noise pulsed light source includes a laser diode drived by an electric pulse generator for emitting repetitive pulsed light; a current source for supplying a bias current to the laser diode; and a photodetector for detecting the repetitive pulsed light emitted from the laser diode; and control means. The control means modulates at least one of the bias current from the current source and the amplitude of a pulse signal generated from the electric pulse generator in accordance with an output signal from the photodetector such that the intensity of the pulsed light is kept unchanged and any noise involved in the same is reduce. A feedback system including the photodetector and the control means has a peak in its frequency characteristics within a frequency band for light detecting in a light measuring system utilizing the low noise pulsed light source.

Abstract: A voltage detecting device using an electro-optical material with a refractive index which is changed by a voltage at a part of an object comprising a light source, comprises an electro-optical material for changing the optical path of the light beam from the light source in accordance with the refraction index of the electro-optical material and a slit or optical fiber extractor at a predetermined position at the output of the electro-optical material for extracting the quantity of light of the light beam at the predetermined position and a detector detecting a voltage at the part of the object from the quantity of light extracted.

Abstract: A light beam is chopped and split into two beams. Intensity of a first beam is changed by using, e.g., an electrooptic material in accordance of a change in a signal to be detected, such as a voltage in an electronic device, and detected by a first photodetector. On the other hand, a second beam is detected by a second photodetector without being subjected to the intensity change. At least one of the outputs of the first and second photodetectors are adjusted so that they become equal to each other when no signal is applied to the light intensity changing means. The difference of the thus adjusted output signals is detected by, e.g., a lock-in amplifier in a narrow band at the chopping frequency.

Abstract: A low noise pulsed light source using a laser diode for generating a short pulsed light of a high repetitive frequency. The low noise pulsed light source includes a laser diode drived by an electric pulse generator for emitting repetitive pulsed light; a current source for supplying a bias current to the laser diode; and a photodetector for detecting the repetitive pulsed light emitted from the laser diode; and control means. The control means modulates at least one of the bias current from the current source and the amplitude of a pulse signal generated from the electric pulse generator in accordance with an output signal from the photodetector such that the intensity of the pulsed light is kept unchanged and any noise involved in the same is reduced.

Abstract: In a wavelength converting device including a light waveguide made of nonlinear optical material and outputting Cherenkov light, a reflecting mirror for reflecting guided light is provided at the end of the light waveguide. The light waveguide may include a light introducing portion and a curved light waveguide smoothly coupled with the light introducing portion. The light waveguide may have a Y-shaped structure including two light introducing portions partially parallel to each other, a junction part at which the two light introducing portions are smoothly joined together, and a linear light generating portion coupled with the junction part.

Abstract: A voltage in a selected area of an object is measured by launching an input light beam into an electrooptic material whose refractive index is changed in accordance with an electric field created by the voltage in a selected area of an object to be measured, and detecting a change in polarization or in a deflection angle of an output light beam from the electrooptic material. A medium having a dielectric constant greater than the air is placed between the area to be measured and the electrooptic material.

Abstract: A first part of input light containing both background light and signal light is extracted by a sampling streak tube and converted to a first electric signal by a photodetector. A second part of the input light containing only background light is extracted by the same sampling streak tube by offsetting the sampling timing and converted to a second electric signal by the photodetector. A signal component corresponding to the signal light is extracted by taking the difference between the first and second electric signals. In one embodiment, the sampling timing is offset by applying a chopping voltage to chopping electrodes provided in the sampling streak tube.