Abstract: A pulsable light source for a spectroscopy instrument is provided, the light source including a xenon flash lamp having an anode and a cathode within a sealed envelope of pressurized xenon gas, the anode and the cathode being spaced so that an arc can be struck between the anode and the cathode without the use of a trigger electrode.

Abstract: A calibrated spectroscopy instrument and a method for calibrating a spectroscopy instrument are disclosed. The spectroscopy instrument includes a monochromator having a drive mechanism comprising a pair of spur gears for rotating a diffraction grating of the monochromator for selecting a desired wavelength. The drive mechanism is calibrated to account for eccentricities in the spur gears to provide an accurate conversion between selected angular settings for the drive mechanism and the wavelength of the diffracted light from the monochromator. The drive mechanism comprises a pinion spur gear and a main spur gear which each have an AGMA (American Gear Manufacturers' Association) rating of at least 10, which allows errors due to random tooth to tooth variations to be neglected. A calibration algorithm is derived which is based on the error due to eccentricities in the spur gears following a precise geometric cyclic pattern.

Abstract: A multi-column liquid chromatography system (10) for performing a plurality of liquid chromatography separations in parallel is based on a column plate structure (12) having parallel grooves (20) formed in a surface (22) of a plate (18), a cover sheet (40) bonded to the surface (22) to cover the grooves (20) and a stationary phase (38) contained in each covered groove (20). Through holes (24, 26) in the plate (18) define respective inlets (24) for the chromatography columns (14) and flow cells (16) at outlets, with the cover sheet (40) providing an optically transparent end wall for the flow cells (16) and another cover sheet (42) bonded to the opposite surface (30) of the plate (18) providing the other optically transparent end wall for the flow cells (16). Thus merely three parts need be provided for a structure for providing the chromatography columns, that is, a plate having grooves and through holes plus two cover sheets.

Abstract: A calibrated spectroscopy instrument and a method for calibrating a spectroscopy instrument are disclosed. The spectroscopy instrument includes a monochromator having a drive mechanism comprising a pair of spur gears for rotating a diffraction grating of the monochromator for selecting a desired wavelength. The drive mechanism is calibrated to account for eccentricities in the spur gears to provide an accurate conversion between selected angular settings for the drive mechanism and the wavelength of the diffracted light from the monochromator. The drive mechanism comprises a pinion spur gear and a main spur gear which each have an AGMA (American Gear Manufacturers' Association) rating of at least 10, which allows errors due to random tooth to tooth variations to be neglected. A calibration algorithm is derived which is based on the error due to eccentricities in the spur gears following a precise geometric cyclic pattern.

Abstract: Apparatus (10) for measuring absolute specular reflectance of a surface of a sample (22) includes a sample holder (12), a light source (18) for transmitting an incident light beam (16) onto a surface of the sample (22) and a detector (26 ) for detecting a specularly reflected component of the incident light. The light source (18), sample holder (12) and detector (26) are mounted and operatively associate (14, 24, 28) to be relatively moveable to vary the angle of incidence of light (16) onto sample (22) and to correspondingly automatically vary the relative position of the detector (26) such that the angle of reflection equals the angle of incidence. In the absence of the sample (22) or upon removal of the sample holder (12), light (16) impinges directly onto detector (26) to directly allow measurement of the absolute intensity of the light beam (16) as a reference measurement. This avoids the need to use intervening optical components such as mirrors which may degrade over time.

Abstract: A plasma source for a spectrometer includes a plasma torch (10) located within a waveguide or resonant cavity (40) for both the electric and the magnetic field components of a microwave electromagnetic field to excite a plasma (54). This produces a plasma (54) having a generally elliptical cross section into which sample is relatively easily injected but which still provides good thermal coupling between the plasma and the sample. The invention gives significantly improved limits of detection compared to prior art microwave induced plasma systems. The torch is preferably axially aligned with the direction of the magnetic field component and may be located within a resonant iris (32) within the waveguide or cavity (40).

Abstract: A method and apparatus for the spectrochemical analysis of a sample in which a solid state array detector (82) is used to detect radiation (62) of spectrochemical interest. The invention involves the use of a shutter (72) adjacent the entrance aperture (70) of a polychromator (74-80) to expose the detector (82) to the radiation (62) for varying lengths of time whereby for short duration exposure times charge accumulation in elements (i.e. pixels) of the detector (82) due to high intensity components of the radiation is limited and for longer exposure times charge accumulation in elements (pixels) of the detector (82) due to feeble intesity components of radiation (62) is increased. This ensures that each reading of the detector (82) includes at least one exposure in which the amount of charge accumulated at each wavelength of interest is neither too little or too great.

Abstract: Apparatus (10) for measuring absolute specular reflectance of a surface of a sample (22) includes a sample holder (12), a light source (18) for transmitting an incident light beam (16) onto a surface of the sample (22) and a detector (26) for detecting a specularly reflected component of the incident light. The light source (18), sample holder (12) and detector (26) are mounted and operatively associate (14, 24, 28) to be relatively moveable to vary the angle of incidence of light (16) onto sample (22) and to correspondingly automatically vary the relative position of the detector (26) such that the angle of reflection equals the angle of incidence. In the absence of the sample (22) or upon removal of the sample holder (12), light (16) impinges directly onto detector (26) to directly allow measurement of the absolute intensity of the light beam (16) as a reference measurement. This avoids the need to use intervening optical components such as mirrors which may degrade over time.

Abstract: Spectroscopy apparatus for spectrochemical analysis of a sample having an excitation source (60) for providing spectral light (62) of the sample for analysis. The spectral light (62) is analysed via an optical system (64-66-68) that includes a polychromator (70, 74-80) and solid state multielement array detector (82). The elements (i.e. pixels) of the detector (82) are serially reel by means (84) to provide light intensity measurements as a function of wavelength. A problem is that the elements (pixels) of the detector (82) continue to accumulate change during the serial read-out. This is avoided by providing an optical shutter (72) for blocking the spectral light (62) whilst elements (pixels) of the detector (82) are being serially read. Shutter (72) has a piezoelectric actuator which is preferably a bimorph mounted as a cantilever. It is preferably located adjacent to the entrance aperture (70) of the polychromator.

Abstract: Spectroscopy apparatus for spectrochemical analysis of a sample having an excitation source (60) for providing spectral light (62) of the sample for analysis. The spectral light (62) is analysed via an optical system (66-66-68) that includes a polychromator (70, 74-80) and solid state multielement array detector (82). The elements (i.e. pixels) of the detector (82) are serially read by means (84) to provide light intensity measurements as a function of wavelength. A problem is that the elements (pixels) of the detector (82) continue to accumulate charge during the serial read-out. This is avoided by providing an optical shutter (72) for blocking the spectral light (62) whilst elements (pixels) of the detector (82) are being serially read. Shutter (72) has a piezoelectric actuator which is preferably a bimorph mounted as a cantilever. It is preferably located adjacent to the entrance aperture (70) of the polychromator.

Abstract: A plasma source for a spectrometer for spectrochemical analysis of a sample is characterized by use of the magnetic field component of applied microwave energy for exciting a plasma. The source includes a waveguide cavity (10) fed with TE10 mode microwave power. A plasma torch (16) passes through the cavity (10) and is axially aligned with a magnetic field maximum (18) of the applied microwave electromagnetic field. Magnetic field concentration structures such as triangular section metal bars (20) may be provided. In an alternative embodiment a resonant iris may be provided within a waveguide and the plasma torch positioned relative thereto such that the microwave electromagnetic field at the resonant iris excites the plasma.

Abstract: A plasma source for a spectrometer for spectrochemical analysis of a sample is characterised by use of the magnetic field component of applied microwave energy for exciting a plasma. The source includes a waveguide cavity (10) fed with TE10 mode microwave power. A plasma torch (16) passes through the cavity (10) and is axially aligned with a magnetic field maximum (18) of the applied microwave electromagnetic field. Magnetic field concentration structures such as triangular section metal bars (20) may be provided. In an alternative embodiment a resonant iris may be provided within a waveguide and the plasma torch positioned relative thereto such that the microwave electromagnetic field at the resonant iris excites the plasma.

Abstract: A method and apparatus for the spectrochemical analysis of a sample in which a solid state array detector (82) is used to detect radiation (62) of spectrochemical interest. The invention involves the use of a shutter (72) adjacent the entrance aperture (70) of a polychromator (74-80) to expose the detector (82) to the radiation (62) for varying lengths of time whereby for short duration exposure times charge accumulation in elements (i.e. pixels) of the detector (82) due to high intensity components of the radiation is limited and for longer exposure times charge accumulation in elements (pixels) of the detector (82) due to feeble intesity components of radiation (62) is increased. This ensures that each reading of the detector (82) includes at least one exposure in which the amount of charge accumulated at each wavelength of interest is neither too little or too great.

Abstract: A method and means for accurately regulating the rate of flow of supply gas to the burner or torch of a spectrometer. The flow rate is controlled by a valve having a closure member which is movable between a position at which it provides maximum obstruction to gas flow, and a position at which it provides minimum such obstruction. The closure member movement is controlled by a pulsed electrical signal so that the closure member moves rapidly and repeatedly between each of the two positions. Gas flow rate through the valve is therefore dependent upon the aggregate of the times the closure member spends in either of the two positions referred to, and that flow rate is changed by varying the frequency and/or pulse duration of the pulsed signal.