摘要:
A compound common-path interferometer including first and second measurement arms for measuring a test object is arranged so that a reference optic of the first measurement arm is not attached to the first measurement arm and a thermally stable spacer between the reference optics of the first and second measurement arms forms a monolithic measurement cavity for maintaining reference surfaces of the reference optics at a fixed spacing and orientation. Separate supports may be provided for the monolithic measurement cavity and th remainder of the first measurement arm.
摘要:
An apparatus for the absolute measurement of a two dimensional optical path distribution comprising: a light source (4) for illuminating an object (26) with light having a plurality of wavelengths: an interferometer (12) for forming an image of at least part of the object, which image comprises a broad band interferogram; a hyperspectral imager (30) in optical communication with the interferometer for spectrally separating the broad band interferogram into a plurality of narrow band two dimensional interf erograms (72, 74, 76); a register (38) for spatially registering the narrow band interf erograms; an extractor for extracting one dimensional intensity signals from corresponding pixels in each narrow band interferogram; and a calculator (100) for calculating the frequency for each point on the object from a one dimensional intensity signal associated with that point.
摘要:
Verfahren und Anordnung zur skalierbaren konfokalen Interferometrie zur Abstandsmessung, zur 3D-Erfassung eines Objekts, zur OC-Tomografie mit einem objektabbildenden Interferometer und mindestens einer Lichtquelle. Das Interferometer weist an jedem optisch erfassten Objektelement einen optischen Gangunterschied ungleich null auf. So weisen die Maxima eines sinusoidalen Frequenz-Wavelets, zugehörig zu jedem erfassten Objektelement, jeweils einen Frequenzabstand Δf_Objekt auf. Zur Aufnahme des Objekts ist mindestens ein spektral integral detektierender, gerasterter Detektor angeordnet. Vorzugsweise ist die Lichtquelle mit Frequenzkamm ausgebildet und die Frequenzkamm-Abstände Δf_Quelle werden beim Messen vorbestimmt über der Zeit in einem Scan verändert. Die Frequenzabstände Δf_Quelle werden dabei für jedes Objektelement zumindest einmal gleich dem Frequenzabstand Δf_Objekt oder gleich einem ganzzahligen Vielfachen der Frequenzabstände Δf_Objekt gemacht. Dies kann aber auch durch einen Scan im objektabbildenden Interferometer erfolgen. Im Scan wird eine Modulation in einem Signalverlauf erzeugt und sequenziell mittels gerasterten Detektors detektiert. Die in diesem Signalverlauf, beispielsweise am Modulationsmaximum, aktuelle Größe der Frequenzkamm-Abstände Δf_Quelle wird bestimmt und dient im Weiteren der Berechnung des zugehörigen optischen Gangunterschiedes eines detektierten Objektelements. Daraus werden Abstände von Objektelementen oder Änderungen der optischen Weglängen, beispielsweise bei einem biologischem Mikroobjekt, in einem Prozess bildgebend bestimmt.
摘要:
A frequency swept laser source for TEFD-OCT imaging includes an integrated clock subsystem on the optical bench with the laser source. The clock subsystem generates frequency clock signals as the optical signal is tuned over the scan band. Preferably the laser source further includes a cavity extender in its optical cavity between a tunable filter and gain medium to increase an optical distance between the tunable filter and the gain medium in order to control the location of laser intensity pattern noise. The laser also include a fiber stub that allows for control over the cavity length while also controlling birefringence in the cavity.
摘要:
Eine Vorrichtung zur Positionserfassung umfasst ein auf eine Messstrecke angewandtes Längenraster (102) sowie eine Längenraster-Variationseinrichtung (B) zur zeitlichen Variation des Längenrasters. Ein Detektor (108) beobachtet das von der Messstreckenlänge und der Variation abhängige Längenraster (102) und erzeugt ein Messsignal. Dieses wird in Abhängigkeit von der zeitlichen Variation des Längenrasters ausgewertet.
摘要:
An airway adapter (16) that comprises a housing (24) and a pressure transducer (45a). The housing comprises a flow path (26) having a first end and a second end, a first pressure port (40) that communicates with the flow path, and a second pressure port (42) that communicates with the flow path. The first pressure port is spaced apart from the second pressure port. The flow restriction is disposed in the flow path between the first and second pressure ports that creates a pressure differential therebetween. The pressure transducer generates a signal that reflects the differential pressure created by the flow restriction between the first and second pressure ports, wherein the pressure transducer comprises an optical interferometer.
摘要:
An apparatus and method for detecting multiple beams from a beamsplitter is disclosed. Some embodiments of the present invention are particularly well-suited for use in microphones, high-sensitivity pressure sensors, vibration sensors, and accelerometer applications. Some embodiments of the present invention generate a differential electrical output signal that is based on multiple detected optical signals. The differential output signal is generated in response to an environmental stimulus, such as a pressure differential or incident acoustic energy. In accordance with the illustrative embodiment, an optical displacement sensor redirects the transmitted beam back through the optically-resonant cavity with an angular offset. Due to the angular offset, the redirected beam (i.e., retransmitted beam) transits the cavity with an intra-cavity path length that corresponds to substantially full transmittance of the retransmitted beam in the absence of the environmental stimulus.
摘要:
An apparatus for interferometric sensing, comprising a plurality of single-longitudinal mode laser sources to each provide radiation at a corresponding plurality of selected wavelengths, and at least one modulator to frequency or phase modulate the radiation from each laser; a plurality of Fabry-Perot interferometers formed by Bragg Gratings written into optical fibre, each interferometer being responsive to one of the said plurality of wavelengths to each produce a reflected or transmitted optical output signal dependent on the corresponding interferometer path length; and one or more demodulators to demodulate the optical output signals and produce a corresponding plurality of measurement signals indicative of optical path lengths of the respective interferometers.
摘要:
An interferometric method including: generating a variable frequency source beam; from the source beam, generating a collimated beam propagating at an angle Ω relative to an optical axis; introducing the collimated beam into an interferometer that includes a reference object and a measurement object, wherein at least a portion of the collimated beam interacts with the reference object to generate a reference beam, at least a portion of the collimated beam interacts with the measurement object to generate a return measurement beam, and the reference beam and the return measurement beam are combined to generate a combined beam; causing the angle Ω to have a first value and at a later time a second value that is different from the first value; and causing the variable frequency F to have a first value that corresponds to the first value of the angle Ω and at the later time to have a second value that corresponds to the first value of the angle Ω.
摘要:
A fiber optic sensor (20) has a hollow tube (26) bonded to the endface (25) of an optical fiber, and a diaphragm (28) bonded to the hollow tube. The fiber endface and diaphragm comprise an etalon cavity (30). The length of the etalon cavity changes when applied pressure or acceleration flexes the diaphragm. The entire structure can be made of fused silica. The fiber, tube, and diaphragm can be bonded with a fusion splice. The present sensor is particularly well suited for measuring pressure or acceleration in high temperature, high pressure and corrosive environments such as oil well downholes and jet engines. The present sensors are also suitable for use in biological and medical applications.