Abstract: A train of transform-limited optical pulses with wavelength close to the zero-dispersion wavelength of the fiber and high and variable peak power, such as to give rise to self-phase modulation, is sent into a fiber. The spectral broadening of the signal exiting the fiber is measured for a number of values of the peak power of the pulses and the nonlinear refractive index is obtained from the angular coefficient of the straight line representing spectral broadening versus peak power.

Abstract: A diffraction grating receives a laser beam from a semiconductor laser diode. Light is diffracted in a first order of diffraction of the grating, through an aperture which selects a desired wavelength, free from side modes of the laser diode. A minor proportion of the light is reflected back by a glass window, and is fed back into the laser diode to stabilise it, preventing mode hopping. The majority of the light of the desired wavelength passes through the window to an output. Because the output light is both free from side modes and not subject to mode hopping, it is suitable for use as the exciting light in spectroscopy, including Raman spectroscopy.

Abstract: A method and apparatus for measuring Polarization Mode Dispersion (PMD) of a single mode optic fiber by providing a PMD measuring instrument with a light source. Light is transmitted serially through the optic fiber being tested and an artefact with a known, stable PMD value. The artefact biases the total PMD measured by the instrument away from zero. The PMD of the optic fiber may then be determined by data reduction of the total measured PMD. The method may also be used to calibrate a PMD instrument.

Abstract: An analytical system for analyzing a fluid sample is disclosed. The analytical system includes a microcolumn for conducting the fluid sample, a light source for delivering light through the microcolumnar wall into the microcolumn near the outlet end of that microcolumn, and an optical fiber aligned with the microcolumn to detect light that radiates from the fluid sample without passing through the microcolumnar wall. The microcolumn has an inlet end and an outlet end. A light-inlet end of the optical fiber is nonfixedly coupled to the outlet end of the microcolumn. As the fluid sample is driven from the inlet end to the outlet end of the microcolumn, a light of a suitable wavelength is directed at the microcolumn near its outlet end to cause light interaction with the fluid sample. As a result, light radiates from the fluid sample. This light is collected by the optical fiber to provide information on the presence or quantity of an analyte in the fluid sample.

Abstract: A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen's A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption.

Abstract: The present invention is directed to methods and apparatus for detecting species in a laser cavity. According to one preferred embodiment, a device according to the invention includes: a source of excitation energy at a first wavelength; a first optic fiber; a resonant cavity; an absorption element; and a detector element. The first optic fiber has at least a first portion which is lasant-doped, and is optically coupled to the excitation source. The doping causes the first optic fiber to amplify light. Thus, in response to light coupled from the excitation source, the first optic fiber is capable of lasing. The resonant cavity surrounds the first portion of the optic fiber and has at least a first wavelength-specific reflector, such that laser light at only a second wavelength is amplified in the cavity. The absorption element can expose a sample to the light contained within the resonant cavity. The detector is optically coupled to the resonant cavity.

Abstract: Apparatus (2) for verifying the performance of optical fibre measurement equipment, comprising a housing (4), a length of optical fibre (6) in a main storage compartment (8), a first compartment (10) containing a first end (12) of the optical fibre (6) that is in the main storage compartment (8), and a second compartment (14) containing a second end (16) of the optical fibre (6) that is in the main storage compartment (8), the optical fibre (6) being stored under substantially zero tension, the first end (12) of the optical fibre (6) being a source end of the optical fibre (6), and the second end (16) of the optical fibre (6) being a detector end of the optical fibre (6).

Abstract: A LED radiates light on a plate held on plate cylinder upon receiving a radiation start signal, so as to form an irradiated area on plate. A photo diode (PD) senses substantially only conventional catoptric light reflected from irradiated area and generates the sensed signal representing the conventional catoptric light intensity. A data processing unit computes the dampening volume based on the sensed signal which is stored in storage device 9, storage device 9 then generates dampening volume signal. The LED is held in such manner that an incident angle of the light in connection with the surface of the irradiated area is made at predetermined angle sufficient for changing the conventional catoptric light intensity sensed by PD in accordance with the dampening volume.

Abstract: A signal for which the amplitude of envelope becomes substantially 0 only for a certain period of time within the time of a period T, and a measured signal having a certain amplitude are synthesized, and the synthesized signal is optically transmitted. When a plurality of reflection points are present on a light transmission line, there is an increase in harmonic distortion or intermodulation distortion as well as in cross modulation distortion after receiving. This increase in cross modulation distortion causes an increase in variation of amplitude of the measured signal.

Abstract: A device for detecting a conduit and for determining at least one characteristic of its content includes a seat for housing at least a portion of the conduit. The seat has first and second zones which are opposite each other with respect to a recess intended to receive the conduit. A light emitter is arranged in the first zone, and has a preferential emission direction oriented towards the recess. A receptor sensitive to the light emitted by the emitter also has a preferential reception direction oriented towards the recess. A first deflector deflects light in the direction of the first zone when a conduit containing a substantially transparent liquid is engaged in the seat.

Abstract: The invention relates to a method for quantitative analysis of one or more elements in a molten metal bath. Light from one or more light sources are focused against the surface of the molten bath and is reflected from the surface of the metal bath to a monochromator or a polychromator connected to detectors for detecting absorbed light in a gas layer associated with the melt of a wavelength or wavelengths corresponding to the element or elements to be analyzed. The absorption signals are proportional to the atom- or molecular density of the components to be analyzed and a function of the thickness of the gas layer and the concentration of the element or elements in the molten metal bath. The concentration of the elements to be analyzed is the calculated based or known relations between absorption signal, the thickness of the gas layer and the temperature of the metal bath.

Abstract: A digital color scanner capable of high color quality includes a light source, a photosensor, a first color filter, a second color filter, a third color filter, and a fourth color filter. The first, second, and third color filters are positioned in an optical path between the light source and the photosensor so as to enable the photosensor to produce a first, second, and third set of color image data during a first calibration scan. The fourth color filter is moved into and out of the optical path between the light source and the photosensor so as to enable the photosensor to produce a fourth, fifth, and sixth set of color image data during a second calibration scan. A circuit produces a set of color correction values from the first, second, third, fourth, fifth, and sixth sets of color image data.

Abstract: Disclosed is an apparatus for measuring on-line the color and color-related properties of a moving sheet. Contrast ratio reflectance measurements are made for providing opacity corrections substantially in real time for a full color spectrum. An optical color sensor in accordance with the invention includes a pair of synchronized spectrometers, the first spectrometer being aligned to view a region of the sheet backed with a highly reflective ("white") material and the second spectrometer being aligned to view a region of the sheet backed with a highly absorptive ("black") material. The use of two spectrometers permits substantially simultaneous "black" and "white" measurements for a full color spectrum. The optical color sensing system further includes two light sources, a flashlamp and a continuously energized tungsten filament lamp. Light beams from the two sources are combined to form a sheet-illuminating third beam approximating the D65 standard source.

Abstract: On-line measurement of fiber orientation and anisotropy in a non-woven web of material is performed by directing three light sources toward a sensing region of the web. Reflectively scattered light from each light source is detected by a pair of light sensors positioned on either side of an incidence plane including the beam of incident light. Back scattered light from each light source is also detected by at least one light sensor positioned generally above the sensing region. Preferably two back scattered light sensors are provided for each light source, one common light sensor and one dedicated light sensor. The signals from the light sensors for each of the light sources are combined to generate resultant fiber orientation signals which are used to compute a fiber orientation angle relative to the machine direction and an anisotropy characteristic for the web.

Abstract: Apparatus for the measurement of optical properties of a quasi cylindrically symmetric transparent object (2), which apparatus comprises source means (11) for providing a source of electromagnetic radiation, illumination forming means for forming an illuminating beam (41), region selecting means for selecting a localised radial region (42), region scanning means for scanning the localised radial region (42) through a range of radial positions, reflection detecting means for detecting a reflected beam (43), beam measuring means for measuring the component of the position where the reflected beam (43) leaves the transparent object (2), supporting means which causes the illuminating beam (41), the reflected beam (43) and an axis of rotational symmetry (1) of the transparent object (2) to lie in a measurement plane, and angle altering means for altering the angle of incidence of the illuminating beam (41) on the transparent object (2).

Abstract: An interferometric fiber optic gyroscope having an intensity servo electronics feedback loop that monitors the intensity of the counterpropagating beams relative to each other, and provides a signal to a modulator to intensity modulate at least one of the signals so as to equalize the intensities or power of the beams to virtually eliminate the Kerr effect.

Abstract: The invention relates to a method of measuring the wavelength of an optical signal such as a light beam. The optical signal is directed toward a detector where its intensity is detected and stored. Several optical elements each having a different wavelength dependence are moved into the path of the optical beam one at a time and for each intensity is detected and stored. The wavelength of the optical signal is then approximately determined based upon the ratio of the detected intensity of the optical signal in the absence of any optical elements and the detected intensities of the optical signal in the presence of each optical element.

Abstract: An apparatus for determining connection loss and reflection attenuation of an optical fiber cord is simple to use and avoids cumbersome and slow two-stage determination using a total reflection cord. The present apparatus has a total reflection device within the measuring apparatus. To determine a contact loss, first end connector of the test cord is inserted in the apparatus, and the output power from the opposite second end connector is measured to give contact loss data. Prior to reflection attenuation determination, the second end is inserted in the total reflection device to measure the reference output power. In this configuration, the light propagated through the test cord is totally reflected back through the test cord at the total reflection device to be measured by a photo-detector, disposed within the apparatus, to give reference light data.

Abstract: A portion of a surface of a sample body is arranged to receive an incident optical beam having an optical intensity I.sub.0. On an opposing surface of the sample body is located an optical detector which senses the intensity I of the resulting optical radiation emerging from the opposing surface of the sample body. In order to measure the thickness t of the sample body, a thickness gauge is located either at another portion of the surface of the sample body or on the optical detector.

Abstract: For the noninvasive investigation of optical fiber lines by means of heterodyne Brillouin spectroscopy light from a pumplaser (10) is directed into one end of the optical fiber line under investigation (16), so that spontaneous Brillouin backscattering is induced in the fiber (16). The light, which is backscattered by spontaneous Brillouin scattering, is superimposed to a lightwave, which is derived from the pumplaser (10), and heterodyned at the detector (46). The output signal from the detector is fed into a spectrum analyzer (50). A part of the light from the pumplaser (10) is directed into a ring resonator (38). The lightwave, which is derived from the pumplaser (10) and which is superimposed with the light, which is backscattered from the optical fiber line under investigation (16), is generated by stimulated Brillouin scattering inside the ring resonator (38).