Abstract:
Die Erfindung betrifft ein verbessertes Spektrometer für die optische Emissionsspektrometrie mit einer Strahlung aussendenden Quelle (11), einem Eintrittsspalt (2), einem Gitter (1), einem Langpassfilter (10), und Detektoren (3, 4, 5, 6), wobei im Betrieb die Strahlung von dem Eintrittsspalt (2) unter einem ersten Einfallswinkel (α1) gegen die Gitternormale (N) auf das Gitter (1) fällt. Das Spektrometer ist dadurch gekennzeichnet, dass - ein erster Spiegel an einer Stelle vorgesehen ist, an der die in nullter Ordnung an dem Gitter reflektierte Strahlung auf den ersten Spiegel fällt, - ein zweiter Spiegel an einer Stelle vorgesehen ist, an der die in nullter Ordnung an dem Gitter reflektierte Strahlung von dem ersten Spiegel auf den zweiten Spiegel fällt, wobei der zweite Spiegel so ausgerichtet ist, dass die an dem zweiten Spiegel reflektierte Strahlung unter einem zweiten Einfallswinkel (α2) auf das Gitter fällt, - wenigstens eine Blende (9) vorgesehen ist, die in den optischen Pfad zwischen dem Gitter, dem ersten Spiegel, dem zweiten Spiegel und dem Gitter zur wahlweisen Unterbrechung dieses Pfades einschaltbar ist, und dass - Mitteln zum Steuern vorgesehen sind, die das Spektrometer steuern, sodass entweder die Blende oder das Filter eingeschaltet sind.
Abstract:
Ein Laserspektrometer weist eine wellenlängendurchstimmbare Laserdiode (4) und eine Kollimatorlinse (12) auf, die das divergente Licht (3) der Laserdiode (4) zu einem parallelen Lichtbündel (13) formt, um damit ein Messgas zu durchstrahlen, anschließend die Lichtintensität zu detektieren und die Konzentration einer interessierenden Gaskomponente des Messgases anhand der Minderung der Lichtintensität durch die Absorption des Lichts (3) an der Stelle einer ausgewählten Absorptionslinie der Gaskomponente zu bestimmen. Um eine Unterdrückung von Interferenzmustern mit konstruktiv einfachen und präzise arbeitenden Mitteln zu erreichen, ist ein MEMS- (Micro Electro Mechanical System-) Spiegel (17) vorhanden, der das Licht (3) der Laserdiode (4) auf die Kollimatorlinse (12) lenkt und von einer Steuereinrichtung (18) zu oszillierenden Kippbewegungen (19) angeregt wird, so dass das von dem MEMS-Spiegel (12) reflektierte Licht (3) auf unterschiedliche Bereiche der Kollimatorlinse (12) trifft.
Abstract:
A method of calibrating an emission spectrometer (10) having a detector (11) capable of detecting spectral components of incident radiation, and a measurement optical path (28) which directs an energy beam (26) to a sample (20) and radiation emitted by the sample when irradiated by the energy beam to the radiation detector (11). The method comprises directing radiation of known spectral characteristic along an alternate path to the detector (11). The detector (11) to detects spectral characteristics of the radiation and makes a comparison with the known spectral characteristics. Drift data is determined on a basis of any variation between the detected and known spectral characteristics. The drift data is stored and subsequently used to adjust detected spectral characteristics of a sample in the measurement optical path (28) produce a drift calibrated output spectral analysis of the sample.
Abstract:
Method and apparatus for detecting, by absorption spectroscopy, an isotopic ratio of a sample, by passing first and second laser beams of different frequencies through the sample. Two IR absorption cells are used, a first containing a reference gas of known isotopic ratio and the second containing a sample of unknown isotopic ratio. An interlacer or reflective chopper may be used so that as the laser frequencies are scanned the absorption of the sample cell and the reference cell are detected alternately. This ensures that the apparatus is continuously calibrated and rejects the baseline noise when phase sensitive detection is used.
Abstract:
The present invention relates to a device for detecting the properties of a web of material transported in the longitudinal direction such as a paper web (20). The device includes a plurality of optical fibres (28) having their input areas (30) each located in the vicinity of the surface of the material web and aligned on said surface, the fibres being secured on a crossbar (26) extending across the material web. The device also includes an infrared spectrometer having the output areas (34) of the optical fibres (28) connected to its input (36) while infrared sensors are connected to the output (44) of said infrared spectrometer. The infrared spectrometer includes a holographic grating (40) for arranging the optical fibers (28) side by side and in one line at the spectrometer input (36) so that the infrared spectra of the signals emitted by the individual optical fibres (28) appear side by side in one line at the spectrometer output (44), and so that the infrared sensors at said output (44) are made in the form of a sensor matrix (46) comprising n lines and m rows of individual infrared-sensitive sensors (48), wherein the spectra from up to m optical fibres (28) can be distributed and detected into up to n spectral areas.
Abstract:
A flicker photometer comprises generating means (1, 8, 4) for generating two beams of light of different colours. Both beams are directed to a viewing means (190), and a subject can vary the intensity of light from one beam relative to the other. The colour of the light seen by the subject is caused to alternate by a shutter (18) which is rotated about an axis by a motor, the shutter having a portion which extends non-perpendicularly relative to the axis to facilitate a compact construction of photometer. The performance of the photometer is improved by screens which scatter light before it reaches the subject. A first of the screens reflectes light from one beam, whilst a second screen transmits light from the other. If light of wavelengths to which the eye is less sensitive is passed through the second screen, whilst light of a wavelength to which the eye is more sensitive passes through the first screen, the screens help to make it practicable for the generating means to use a single lamp (1) to produce the light for both beams.
Abstract:
An adjustable slit mechanism for a monochromator is provided. The adjustable slit mechanism (81; 300) may be used in a monochromator of a fibre optic atomic absorption spectrometer. The adjustable slit mechanism comprises a first slit member (302) including a first slit edge, a second slit member (304) including a second slit edge, a slit adjusting cam (306) having a variable radius, a first arm (308) connected to the first slit member, and a second arm (310) connected to the second slit member. The first slit edge (312) is arranged opposite the second slit edge (314) to define an adjustable slit of the adjustable slit mechanism. The first arm (308) and the second arm (310) are resiliently biased against the slit-adjusting cam such that rotation of the slit adjusting cam adjustably separates the first arm and the second arm for adjusting a width of the adjustable slit. The invention also provides a slit assembly for a monochromator and a monochromator assembly.