Abstract:
In order to extend the available spectral range and to optimize spectral resolution while retaining a compact spectrometer setup, two diffraction gratings are operated with congruent focal curves in a Paschen-Runge geometry. The spectrometer features only one entrance slit and allows an adequate adaptation of the covered spectral range to the demands of analytical spectrometry. Apart from photomultiplier tubes commercial solid-state linear array sensors placed tangential at the Rowland circle are used for simultaneous detection of the spectrum. By employing angular cut cylindrical mirrors the radiation is deflected by 90% upward or downward in an alternating series. In this way two effects are achieved, an almost complete detection of the spectrum firstly and secondly a gain of intensity by focusing of radiation perpendicular to the plane of dispersion.
Abstract:
In the monochromator, when measured beam which is diffracted by a plane diffraction grating is collected by a collimator to be returned, the measured beam is displaced by a displacement member in a direction parallel to rulings of the plane diffraction grating and is passed through a first cut-off slit having a slit of a predetermined width formed in a direction perpendicular to the direction of the rulings.
Abstract:
Light from an object such as a cell moving through an imaging system is collected and dispersed so that it can be imaged onto a detector. The light can be emitted from a luminous object or can be light from a light source that has been scattered or not absorbed by the object or can include a light emission by one or more probes within or on the object. Multiple objects passing through the imaging system can be imaged, producing both scatter images and dispersed images at different locations on one or more detectors. In one embodiment, the detector is divided into a plurality of zones so that each of a plurality of different images are spectrally dispersed onto a different zone of the detector.
Abstract:
An embedded data acquisition and control system for a precision instruments, such as a non-invasive glucose prediction instrument is disclosed. One feature of the invention provides synchronization of stepper motor position and analog-to-digital converters. An embedded controller is provided that controls the stepper motor driver directly to minimize the wavelength shift error due to the asynchronous condition. The controller synchronizes the event of reading the A/D converters with each stepper motor position. Because the stepper motor controls the wavelength of the monochromator optical output, the net result is that each A/D conversion recorded by the embedded controller is precisely tracked to a specific wavelength. Another feature of the invention provides closed loop motor position control for enhanced system performance. In the closed loop system, a position encoder is coupled to the stepper motor shaft. The encoded position signal is processed by a digital encoder at the bipolar stepper motor drive, resulting in an actual position feedback to the embedded controller. Because the embedded controller has the position feedback, it can initiate the next step command as soon as the position feedback reaches its target. The step rate is increased by reducing the time delay that was set by a conservative value as indicated in the open loop control mode. One advantage of this method is to achieve highest speed in all load conditions without missing steps. A further feature of the invention provides optical Isolation to minimize motor noise. Thus, optical isolation is provided at a bipolar stepper motor drive and embedded controller interface. To maximize system sensitivity, optical isolation is implemented between the embedded controller and the stepper motor drive.
Abstract:
Light from an object such as a cell moving through an imaging system is collected and dispersed so that it can be imaged onto a time delay and integration (TDI) detector. The light can be emitted from a luminous object or can be light from a light source that has been scattered or not absorbed by the object or can include a light emission by one or more probes within or on the object. Multiple objects passing through the imaging system can be imaged, producing both scatter images and dispersed images at different locations on one or more TDI detectors.
Abstract:
An optical spectrum analyzer of novel design, in which several different spectra can be measured and analyzed simultaneously. A measuring signal is used as a reference signal for calibrating the optical spectrum analyzer. The light rays are admitted via a coupling device with several coupling apertures arranged in a line; and via a separate decoupling device comprising respective decoupling apertures arranged in a line, the light rays are decoupled. Height offset is realized by a 90° deviation prism. The arrangement makes possible simultaneous analysis of several optical lines with little retroreflection as well as uninterrupted calibration of the measuring process.
Abstract:
An on-line halogen analyzer system and method of use for semiconductor processing effluent monitoring. The system includes sampling the effluent stream into an absorption cell, and passing UV-Visible light through the effluent sample in the cell. After passing through the sample the light is collected by a photo detector for real-time wavelength-selective absorption analysis. The system provides simultaneous determination of the concentrations of multiple halogen gases (e.g. F2, Cl2, Br2, and I2) in semiconductor processing effluent streams. The invention can be used for chemical vapor deposition (CVD) chamber cleaning endpoint determination and to improve fluorine utilization efficiency in remote plasma downstream CVD chamber cleaning processes.
Abstract:
An optical filter is provided in the form of a subtractive double monochromator. In each dispersive stage, a concave mirror focuses light between a diffraction grating and a transfer mirror between the stages. Light which misses the transfer mirror is rejected. To reduce aberrations over a wide bandwidth, the radius of curvature R of the mirror is centered on the grating and the transfer mirror has a radius of curvature R/2 and is located midway between the mirror and the grating. The mirror 34 thus coincides with the locus of the focus of the spectral image in both stages.
Abstract:
A novel wavelength measurement method wherein an optical pulse is launched into a dispersive medium with known dispersion properties, such as a dispersion compensating fibre or a dispersion compensating Bragg grating. The specific wavelength of the dispersion-induced light beam is obtained by measuring the propagation time delay through the dispersive medium and relating that propagation time to the calibrated dispersive medium.