Abstract:
An optical attenuator (10) includes: an optical splitter (11), a collimator (12), two detectors (51, 52), a first and second reflectors (21, 22), an attenuating element (3) and a driving device (4). The optical splitter includes a ferrule (112) and a GRIN (graded index) lens (113). The collimator is similar to the optical splitter. Input optical signals are transmitted from an input fiber (110) through the optical splitter and are then directed to the first reflector. The optical signals reflected by the first reflector pass through the attenuating element and are subsequently reflected to the collimator by the second reflector. The two detectors receive sampling signals via an input and an output sampling fibers (111, 112). The driving device can drive the attenuating element in response to the attenuation ratio coming from the two detectors.
Abstract:
A wave-guide arrangement includes a conical shell, a wave-guide mounted in the conical shell, a thermopile fastened to the wave-guide and adapted to detect radiation heart, the wave-guide having an isothermic base, a front neck perpendicularly extended from and formed integral with the center of the front side of the isothermic base, a coupling portion disposed at the center of the rear side of the isothermic base and adapted to receive the thermopile, and a center wave-guide hole axially extended through the neck, the isothermic base and the coupling portion, and adapted to guide radiation heat to the thermopile.
Abstract:
An accelerometer useful over a very wide range of gravitational forces is described. The device is based on the use of an optical fiber having a free cantilevered end subject to movement due to inertial lag. A constant output light source is located at one end of the optical fiber and a multicell photoarray is placed adjacent the free end of the fiber so that movement of the fiber due to acceleration can be readily detected. The individual cells in the array are preferably masked so that the output is a function of the lateral displacement of the fiber. This gives a linear or other voltage output curve related to the magnitude and direction of fiber movement. A multiplexing circuit repetitively samples the output of each photocell in the array. The output is preferably digitized and can provide a direct input into a computer that will convert data on acceleration to associated position, velocity and force involved.
Abstract:
A fiber optic cable forms a temperature sensor arranged along an object or space to monitor the temperature thereof and detect overheating or fire conditions. An end of the sensor is con5 nected through an interface to a laser emitter and an optical receiver, which are further connected to a computer. The computer controls the laser emitter to emit a laser pulse into the sensor. The optical receiver receives the resulting reflection signal from the sensor, and provides a corresponding signal to the computer to be evaluated in connection with a nominal comparison signal. If any location of the sensor is subjected to an unacceptable temperature increase, the sensor's refractive characteristics are changed, to cause an additional reflection pulse in the reflection signal. By evaluating the amplitude and the return time of the additional reflection pulse, the temperature level and the location of the overheating condition are determined by the computer.
Abstract:
Use of an optical fibre for the direct receipt of heat radiation for transmission to a remote pyrometer is enabled by the provision of an apertured, contaminant free compartment in the component being heated, and aligning the heat receiving end of the optical fibre with the aperture so as to receive radiated heat from within the compartment.
Abstract:
A device for temperature measurement uses an optical system to image the heat radiation emanating from a measurement spot on an object of measurement onto a detector. A sighting arrangement is also provided which has a diffractive optical system by which a light intensity distribution is produced which corresponds to the position and size of the measurement spot on the object of measurement.
Abstract:
An optical tweezer device for capturing minute bodies on a stage in accordance with very fine patterns. A fiber array light source of the device is equipped with a laser module which is structured with a high-luminance, high-power multiplex laser light source. High-intensity laser light which is emitted from this fiber array light source is modulated by a DMD and focused by a microlens array. The focused light enters corresponding optical fiber cores which are arranged in a matrix form at an array head, and is guided in the fibers. The light focused by the microlens array is caused to enter the fiber cores corresponding to the microlenses with high efficiency. The optical fibers are two-dimensionally arrayed to correspond with pixel portions of the DMD. High-intensity laser light is emitted from the array head in accordance with an on-off pattern of the DMD.
Abstract:
Fiber grating environmental measurement systems are comprised of sensors that are configured to respond to changes in moisture or chemical content of the surrounding medium through the action of coatings and plates inducing strain that is measured. These sensors can also be used to monitor the interior of bonds for degradation due to aging, cracking, or chemical attack. Means to multiplex these sensors at high speed and with high sensitivity can be accomplished by using spectral filters placed to correspond to each fiber grating environmental sensor. By forming networks of spectral elements and using wavelength division multiplexing arrays of fiber grating sensors may be processed in a single fiber line allowing distributed high sensitivity, high bandwidth fiber optic grating environmental sensor systems to be realized.
Abstract:
A fiber optic cable is used as a distributed temperature sensing (DTS) transducer for temperature profile measurements in a protective underground duct in which a high voltage (HV) cable has already been laid. The sensing cable is not incorporated into the power cable itself, and in some installations does not have direct physical contact with the HV cable. The sensing cable is installed externally (along side) of the HV power cable, either in direct surface contact with the HV cable, or alternatively, the fiber optic sensing cable is installed in a small diameter guide tube that is placed in the upper annulus between the HV cable and the protective duct. The sensing fiber and one or more guide tubes are installed in a loose bundle at least in part by fluid drag forces (blowing with pressurized air) using conventional cable launching equipment. Large diameter guide tubes are placed on opposite sides of the HV cable in a wedging position that blocks shifting movement of the small guide tubes and optical fibers down into the lower cusp-shaped space between the HV cable and the protective duct.
Abstract:
The invention relates to a method and to a device (1) for testing materials by determining and displaying as an image temperature differences above a threshold value on the surface of test objects (8). In a first step, a camera for determining and displaying as an image the temperature differences above a threshold value is used to determine the temperatures of object elements (22) within a test area (14) of the test object (8) facing the camera. The test area (14) is then provided with heat by means of a laser beam (4) in such a manner that the temperature of the surface of the test object (8) rises in the test area (14) by at least the amount of the threshold value. The object elements (22) are displayed as image elements in such a manner that the temperature differences above the threshold value between the object elements (22) are visible. The cool-down of the test area (14) is indicated by means of the image elements (20).