210 results about "Wavelength calibration" patented technology

A system for calibrating a plurality of optical modules includes a plurality of optical signal sources and optical signal degradation elements optically communicating with input switches. The input switches supply optical test signals to optical modules (units under test) plugged into a common shelf. Calibration switches including variable optical attenuators may be used to adjust the input signal levels and alternately supply adjusted signals to an optical power meter and the units under test. A controller is used to control the adjustment and thereby provide defined, measured signal levels to the units under test. By reading data from the units under test and using these defined signal levels, the optical modules may be calibrated or diagnosed. Output optical switches are used in a similar fashion to calibrate or diagnose the outputs of the units under test. In addition to input/output power calibration, the invention may also perform wavelength calibrations.

When using a spectral endoscope, the spectral characteristic can be precisely set to be suitable for use conditions. There is provided a spectral endoscope (1) comprising: a channel (3) arranged along a longitudinal direction in an insertion unit to be inserted into a body cavity; an image pickup section (8) which captures an image in a vicinity of the distal end of the insertion unit (2); a variable spectral section (7) capable of changing the wavelength of light to be incident into the image pickup section (8); a reference light member (10) which emits light of a known wavelength characteristic, or has a known absorption characteristic, and is to be introduced into a field-of-view range of the image pickup section (8) through the channel (3); a control unit (11) which controls the image pickup section (8) to capture an image of the reference light member (10) that has been introduced through the channel (3), while controlling the variable spectral section (7) to change the wavelength of light to be incident into the image pickup section (8); and a calibration unit (12) which calibrates the spectral characteristic of the variable spectral section (7) according to the image of the reference light member (10) that has been captured by the image pickup section (8).

Described is a method for calibrating a spectrophotometric apparatus which is used to measure analytes in plasma and/or serum samples based on the calibration of a First Apparatus, and for recalibrating such apparatus, including recalibration of the First Apparatus all using synthetic calibrators. These apparatus use absorption of radiation to measure analytes in serum or plasma samples. The method described includes using synthetic calibrators which are submitted to the First Apparatus for measurement and compared with measurements of similar calibrators in a Second Apparatus and using the comparison to derive concentrations of analytes in samples measured on the Second Apparatus. As an alternative to making all apparatus identical, in terms of wavelength calibration, the absorbances of all apparatus should be mapped onto a standard set of wavelengths.

A multi-channel, reconfigurable fiber-coupled Raman instrument uses fiber optic switches for laser and calibration light routing to facilitate automated calibration, diagnosis and operational safety. The system allows wavelength axis calibration on all channels; laser wavelength calibration (including multiple and/or backup laser options); fiber coupling optimization; fault detection/diagnosis; and CCD camera binning setup. In the preferred embodiment, dedicated calibration channels surround data channels on a 2-dimensional CCD dispersed slit image implemented using a unique cabling architecture. This “over/under” calibration interpolation approach facilitates quasi-simultaneous or sequential calibration/data acquisitions. CCD binning between sequential calibration and data acquisitions enables higher density multi-channel operation with tilted images based upon a multiplexed grating configuration. A diamond sample is used as a Raman shift reference for laser calibration, preferably in the form of a small disc sampled with an edge-illuminating probe using two unfiltered fibers. Detection of beam transmitted through the diamond reference is also used to optimize laser coupling efficiency with motion servos. An “intrinsically safe” laser interlock circuit also serves as current source for probe head “laser on” diode indicator. The integrity of key components is monitored through strategically placed photodiodes positioned, for example, at fiber bends to detect light leakage from bent fiber as verification of commanded laser path through fiber switches and at neon and halogen lamp locations to verify lamp operation. The optical switches used for calibration may also be configured for use as a laser shutter.

The invention concerns methods for the wavelength calibration of spectrometers and in particular secondary spectrometers which achieve considerably better calibration accuracies than the conventional peak search methods especially for spectrometers with a relatively large bandwidth. The methods according to the invention are based on the principle of a stepwise relative shift of corresponding measured-value blocks of a model and calibration spectrum where a correlation value is calculated for each shift step. A shift value is determined for each measured-value block at which the correlation value reaches an optimum. A value pair consisting of a position marker of the measured-value block and the associated shift value is determined for each measured-value block. These value pairs represent the design points for fitting to a suitable assignment function. The coefficients obtained in this manner can be used directly as coefficients of a wavelength assignment or be combined with the coefficients of an existing first wavelength assignment in that they for example replace these coefficients or are offset against the coefficients of an existing first wavelength assignment.

The invention discloses a device and method for calibrating an optical fiber scanning light source wavelength based on gas absorption spectral lines. The device and method are suitable for the precise locating of a scanning light source output wavelength based on an F-P filter in the field of optical fiber communication and sensing. The device and method provide multiple reference wavelengths for the wavelength calibration of an optical fiber scanning light source by utilizing the multiple absorption spectral lines of gas molecules in a near-infrared wave band, and are high in stability. In the calibration process, broadband light passes through the F-P filter driven by continuous voltages, outputs narrow-linewidth scanning light, and interacts with the gas molecules in a gas chamber to form gas absorption spectrums. Through base line extraction, absorption peak fitting and absorption wavelength query, the driving voltage and the absorption wavelength corresponding to each absorption spectral line of the gas are obtained. According to the voltage-wavelength corresponding relation of each spectral line, calibration is carried out on the output wavelength of the optical fiber scanning light source, and system wavelength locating is carried out through spline interpolation. The device and method have the advantages of being simple in device, easy to integrate, high in precision and the like, and have wide application prospects.

Methods and apparatus are provided for calibrating a fiber optic gyroscope (FOG) to compensate for wavelength fluctuations. The wavelength of the light propagating in the gyroscope is accurately determined by obtaining wavelength indicia for light originally produced by the sensor light source and for light produced by a reference light source. The wavelength indicia may include normalized power values, such as sum and difference indicia, obtained from two outputs of a wavelength division multiplexer. Such information can be used to determine the wavelength of light produced by the sensor light source, and to adjust a scale factor or other operating parameter of the gyroscope as a function of the determined wavelength. This adjustment, in turn, can be used to compensate the output of the sensor to account for wavelength variations.

The invention discloses a fiber bragg grating sensing system based on a narrow-band scanning light source and an operation method. In the system, one of narrow-band light wave laser beams which are outputted by a tunable laser and have periodical changeable wavelength is divided into N paths to be incident into N sensor channels; the FBGs (fiber bragg grating) with non-overlapping wavelength change range in each sensor channel are arranged from short wavelengths to long wavelengths, from near to far according to the characteristics; another path is entered to an etalon of a calibrating channel; reflected light of each sensor channel and transmission light of the etalon are accessed to FPGA (field programmable gate array) through photoelectric detectors and a signal processing circuit; the output end of FPGA is connected with an industrial personal computer; the control signal is accessed to the tunable laser. The operation method is as follows: the narrow-band laser scanned by the tunable laser periodically is accessed to each sensor channel, and reflected when the wavelength of the laser is identical to the characteristic length wave of certain FBG; another laser path is transmitted through the etalon; the two paths of laser are converted into electric signals to be accessed to the industrial personal computer, so as to obtain the FBG wavelength variation. The fiber bragg grating sensing system can continuously scan with real-time wavelength calibration precision up to 1 micro strain. The FPGA are parallel to collect and process the wavelength, so that the demodulation speed is high.

Wavelength reference apparatus for use in calibrating a tunable Fabry-Perot filter or a tunable VCSEL, whereby the device may be tuned to a precise, known wavelength, the wavelength reference apparatus comprising an LED, where the LED is chosen so as to have an emission profile which varies with wavelength; an etalon, where the etalon is chosen so as to have a transmission profile which comprises a comb of transmission peaks, with each transmission peak occurring at a precise, known wavelength; and a detector for detecting the light emitted by the LED and passing through the etalon; whereby when a tunable Fabry-Perot filter or tunable VCSEL is positioned between the etalon and the detector, and the device is swept through its tuning range by varying the tuning voltage applied to the device, the known transmission wavelengths established by the LED and the etalon can be correlated to counterpart tuning voltages of the device, whereby to calibrate the device.

The invention discloses a multi-channel intelligent optical testing device which comprises a light source, a light source control circuit, a wavelength calibration monitoring module and an optical switch which are sequentially connected. One output end of the optical switch is sequentially connected with a polarization controller, a 2*2 shunt and a 1*N optical splitter. One output end of the 2*2 shunt is connected with a first optical power detector, and one input end of the 2*2 shunt is connected with a second optical power detector. The other output end of the optical switch is connected with an N*N shunt, and output ends of the N*N shunt are connected with array optical power detectors in a one-to-one correspondence mode. The light source control circuit, the wavelength calibration monitoring module, the optical switch, the polarization controller, the first optical power detector, the second optical power detector and the array optical power detectors are connected with a control unit. The testing device can test optical indexes of a multi-channel module.

The invention relates to a temperature control tunable optical fiber filter based on a micro-nano optical fiber and manufacturing method. The temperature control tunable optical fiber filter is characterized in that the filter at least includes a micro-nano optical fiber (1) and a planar optical waveguide (2), the micro-nano optical fiber (1) is manufactured with a single-mode optical fiber (3) into a structure in which diameters of the two ends are unchanged and the middle is a micro-nano waist region through a fused biconical taper process, the length of the thin waist region is at least larger than or equal to that of the planar optical waveguide (2), and the micro-nano optical fiber (1) and the planar optical waveguide (2) are pasted through an optical adhesive (4) to manufacture a waveguide coupling structure. The filter proposed by the invention is of an all-optical fiber structure, optical transmission loss is low, and filtering stability is high. Bandpass and band-stop filtering tuning in a relatively wide range can be realized through change of temperature, the repeatability is relatively high, and extra complex wavelength calibration equipment is not needed.

The invention discloses a multi-dimension complex calibrating method of a fiber optic spectrometer. The calibrating method comprises the steps of multi-dimension wavelength calibration and multi-dimension amplitude calibration, wherein multi-dimension calibration is executed to the wavelength and the amplitude by introducing temperature factors so that stability of the spectrometer is increased at high and low temperature; in the calibrating method, various operating factors of CCD (Charge Coupled Device) are fully considered, and multi-dimension complex calibration is executed to the fiber optic spectrometer in combination with multiple dimensional calibration factors of space, time, temperature and light intensity to ensure reliability of test results.

The invention discloses a wavelength calibration way for a optical fiber spectrometer, and consists of the following steps, A) a standard light source is applied, standard spectrum is collected through the spectrometer, the image element order number k_i of spectrometer receiving element linear array CCD is determined corresponding to the standard light source of different practical wavelength Lambada_i; B) the arbitrary three practical wavelength Lambada _i and the corresponding image element order number k_i are chosen, and in accordance with the above formula, a₁, a₂, and a₃ are determined; C) according to the values of a₁, a₂, a₃ from step B), the calibration calculation wavelength value Lambada_i is determined corresponding to every image element order number k_i, wherein, the Lambada_i is a calibrated wavelength value. The calibrating way of the optical fiber spectrometer is provided by the present invention, the calibration deviation of the calibrating way is much smaller than the calibration deviation of the prior art, and accurate calibration can be done with 3 arbitrary standard spectrum lines, not only the flexibility of the calibration is improved but also the application is easier and more convenient. The invention discloses the calibrated spectrometer applying the above mentioned way at the same time.

The invention relates to a parallel double-chamber tunable fiber Fabry-Perot filter comprising two fiber Fabry-Perot filters, a supporting seat and a piezoelectric cermic driver. The two fiber Fabry-Perot filters are connected in parallel to be fixed on the supporting seat and simultaneously tune the wavelength under the drive of the piezoelectric cermic driver; the tardiness and the nonlinearity of the piezoelectric cermic driver have the same influence to the two fiber Fabry-Perot filters; the wavelength calibration parameter of the other fiber Fabry-Perot filter can be simultaneously obtained by calibrating the wavelength of one of the fiber Fabry-Perot filters through a Fabry-Perot etalon and a fiber grating, thereby realizing that one of the filters measures a passive device and the other filter measures the spectrum emitted by an active device.

Described is a method for calibrating a spectrophometric apparatus and determining the concentration of an analyte in a sample. This method involves incorporating at least one primary calibration algorithm that uses an order of derivative of absorbance obtained for at least one of a standard set of wavelengths, on a second apparatus. The absorbance values of the sample are measured on the second apparatus at three or more wavelengths from a wavelength calibration table. Interpolated absorbance values are derived from the measured absorbance values for wavelengths from a standard set of wavelengths. A derivative of the interpolated absorbance values is obtained, using the same order of derivative used by the first apparatus. Followed by calculating a concentration of the Analyte in the sample, by applying the Primary Calibration Algorithm to the derivative. The present invention also provides for a medium storing instructions adapted to be executed by a processor to determine analyte concentration within a sample, as defined by the above method.

The invention relates to a laser wavelength calibration method and device and a gas concentration analyzer. The wavelength calibration method includes the steps: storing a zero-gas secondary harmonicspectrum and a standard concentration secondary harmonic spectrum acquired in calibration; acquiring the secondary harmonic spectrum of gas to be detected; determining the absorption peak center position of the gas to be detected according to the maximum value of an absorption peak when judging that the concentration of the gas to be detected is within a first range, acquiring deviation between the absorption peak center position of the gas to be detected and the absorption peak center position of the standard concentration spectrum and generating feedback signals according to the deviation exceeding a preset value to calibrate wavelengths; determining the absorption peak center position of the gas to be detected according to the similarity of the spectrum of the gas to be detected and thezero-gas spectrum when judging that the concentration of the gas to be detected is within a second range, acquiring deviation between the absorption peak center position of the gas to be detected andthe absorption peak center position of the zero-gas spectrum and generating feedback signals according to the deviation exceeding the preset value to calibrate the wavelengths. The first range is notoverlapped with the second range, and the value of the first range is larger than that of the second range.

The invention relates to a method for on-line real-time marking the wavelength when demodulating the sensing wavelength of optical fiber Prague grating, belonging to the optical fiber sensing measure technique. Wherein, the first end of three-end optical circulator is connected to the broad-band light source, the second it connected to the optical fiber Prague grating sensor, and the third end is connected to the wavelength demodulator, to realize the wavelength mark; it uses one optical fiber Prague grating as the wavelength reference device, to be serially connected with the optical fiber Prague grating sensor, while the reference device is packed in a constant-temperature groove, whose temperature accuracy is+-0.1Deg. C; and the wavelength reflected from the reference device has stability on the spectrum; using it as norm to be arranged at the upper or lower end of Prague wavelength display spectrum of optical fiber Prague grating sensor, to mark the wavelength when demodulating the sensing wavelength of optical fiber Prague grating. The invention has simple operation and lower cost.

A spectrometer assembly (10) comprises a light source (11) with a continuous spectrum, a pre-monochromator (2) for generating a spectrum with a relatively small linear dispersion from which a spectral portion is selectable, the spectral bandwidth of such spectral portion being smaller than or equal to the bandwidth of the free spectral range of such order in the echelle spectrum wherein the centre wavelength of the selected spectral interval is measurable with maximum blaze efficiency, an echelle spectrometer (4) with means for wavelength calibration, an entrance slit (21) at the pre-monochromator (2), an intermediate slit assembly (50) with an intermediate slit (3) and a spatially resolving light detector (5) in the exit plane of the spectrometer for the detection of wavelength spectra. The assembly is characterised in that the width of the intermediate slit (3) is larger than the monochromatic image of the entrance slit generated by the pre-monochromator at the location of the intermediate slit, and means for calibrating the pre-monochromator are provided, which are adapted to calibrate the light of the light source with a continuous spectrum on the detector to a reference position.

The invention discloses a method for calibrating the spectral wavelength of an optical grating rotary light splitting spectrograph. The method is characterized in that a relation between the optical wavelength and reading of an optical encoder is derived by using an optical grating equation working under a Littrow condition, and a theoretical calibration model is established; spectral wavelength calibration is carried out by using a two-point equation solving method; and finally, initial wavelength positioning is carried out by using calibration parameters in order to ensure the consistency in target position when different spectrographs measure gratings with the same wavelength. The method disclosed by the invention has the advantages that (1) the calibration steps are simple and effective, and the calibration workload and the calculation amount are reduced under the premise of ensuring the calibration precision; (2) the calibration work can be completed by only using two standard light sources with different wavelengths under the premise of ensuring the accuracy of the wavelength, the calibration time is short, the calibration efficiency is high, and the calibration cost is low; and (3) the calibration model is established through known theories, curve fitting is not required to be adopted, factors, which influence calibration, among different spectrographs are considered comprehensively, calibration is carried out more reasonably and more feasibly, and the calibration precision is higher.

In a wavelength calibration method, an observed spectrum of a light that has a wavelength band is obtained, wherein the light has at least an attenuated wavelength component that corresponds to at least a predetermined absorption wavelength that is included in the wavelength band. A corrected spectrum is then obtained from the observed spectrum, wherein the corrected spectrum has reduced dependencies upon the full width at half maximum of an emission band of the light and upon an intensity ripple period of the light.