Abstract: An unknown spectrum obtained from infrared or other spectroscopy can be compared to spectra in a reference library to find the best matches. The best match spectra can then each in turn be combined with the reference spectra, with the combinations also being screened for best matches versus the unknown spectrum. These resulting best matches can then also undergo the foregoing combination and comparison steps. The process can repeat in this manner until an appropriate stopping point is reached, for example, when a desired number of best matches are identified, when some predetermined number of iterations has been performed, etc. This methodology is able to return best-match spectra (and combinations of spectra) with far fewer computational steps and greater speed than if all possible combinations of reference spectra are considered.

Abstract: A mounting system allowing rapid removal and replacement of optical components within an instrument includes a base unit connected to the instrument, and a carrier unit which includes an optical component. The carrier unit is magnetically attracted to the base unit, with mounting nubs extending from one of the base and carrier units being received in depressions defined in the other of the units. Preferably, the magnets on the base and carrier units are aligned, and V-groove depressions receive hemispherical surfaces presented by the mounting nubs. When the base and carrier units are generated using precision manufacturing methods, the optical component on the carrier unit can maintain a predefined alignment upon the base unit (and the instrument) with sub-micrometer precision between successive mountings and removals of the carrier unit, thereby avoiding the need to realign the optical component within the instrument every time the carrier unit is removed and replaced.

Abstract: A spectrometer operator may specify a desired signal to noise ratio (SNR) to be attained when collecting spectra from a sample. The SNR from a single brief sample exposure is used to determine the maximum exposure time achievable without overloading the spectrometer. If the desired SNR is greater than the SNR of an exposure using the maximum exposure time, multiple exposures can be taken at the maximum exposure time, and can be combined (e.g., averaged or summed) to obtain a spectrum having a SNR which at least approximates the one desired. If the desired SNR is less than the SNR of an exposure using the maximum exposure time, then only a single exposure is needed, and the exposure time can be scaled using the SNR from the single brief sample exposure to achieve a SNR which at least approximates the one desired.

Abstract: An optical method and apparatus is utilized to provide rapid spatial averaging over a large sample area in a Raman spectrometer, without defocusing of the optical source or the collection optics. Spatial averaging provides a representative spectrum of a sample that is inhomogeneous, either in its composition or surface characteristics. The spatial averaging configurations and methods disclosed herein also reduce sample degradation or burning resulting from the high intensity of the directed optical source. Moreover, the dimensions of the sample area of the spatial averaging methods and configurations of the present invention are adjusted to match specific sampling requirements.

Abstract: A system for performing spectral microanalysis delivers analysis results during the course of data collection. As spectra are collected from pixels on a specimen, the system periodically analyzes the spectra to statistically derive underlying spectra representing proposed specimen components, wherein the derived spectra combine in varying proportions to result (at least approximately) in the measured spectra at each pixel. Those pixels having the same dominant proposed component, and/or which contain at least approximately the same proportions of the proposed components, may then have their measured spectra combined (i.e., added or averaged). These spectra may then be cross-referenced via reference libraries to identify the components actually present.

Abstract: An X-ray detector using a semiconductor detector, most preferably a Silicon Drift Detector, utilizes a field effect transistor or other voltage-controlled resistance to generate an output voltage proportional to its input charge (which is generated by the X-ray photons incident on the semiconductor detector). To keep the charge (and thus the output voltage) to an acceptable range—one wherein the relationship between output voltage and input charge is substantially proportional—a feedback circuit is provided between the output and input terminals, wherein the charge on the input terminal is depleted when the output voltage begins leaving the desired range. Preferably, this is done by a comparator which monitors the output voltage, and provides a reset signal to the input terminal when it begins moving out of range. Alternatively or additionally, the reset signal may be a pulse supplied to the input terminal from a pulse generator activated by the comparator.

Abstract: In a spectroscopic microscope, a video image of a specimen is analyzed to identify regions having different appearances, and thus presumptively different properties. The sizes and locations of the identified regions are then used to position the specimen to align each region with an aperture, and to set the aperture to a size appropriate for collecting a spectrum from the region in question. The spectra can then be analyzed to identify the substances present within each region of the specimen. Information on the identified substances can then be presented to the user along with the image of the specimen.

Abstract: A confocal spectrometer provides astigmatic optics which supply a monochromator or spectrograph with the image of a sample, with the astigmatic optics thereby providing separate first and second (tangential and sagittal) focal planes for the image. The monochromator/spectrograph has an entrance slit oriented along one of the focal planes, and this slit defines the spectral resolution of the monochromator/spectrograph and the field of view of the sample in one direction (in one focal plane). A supplemental slit is situated outside the monochromator/spectrograph adjacent the entrance slit, with the supplemental slit being oriented along the other focal plane. The supplemental slit therefore defines the field of view of the sample in a perpendicular direction (in the other focal plane). By varying the width of the supplemental and/or entrance slits, one may easily achieve the desired field of view.

Abstract: A spectrometer collects background spectra during the idle time in which it is not collecting spectra from a sample. These spectra are collected over a range of exposure times, allowing the background reading on each pixel to be modeled as a function of exposure time. When sample spectra are then collected, the exposure time for the sample spectra can be used with the modeled function to compute an estimated background within the sample spectra. The estimated background can then be subtracted from the sample spectra, thereby reducing the noise therein.

Abstract: A spectroscopic microscope includes a laser or other light source which emits light from the entrance aperture of its spectrograph, and also includes a light sensor situated on the microscope sample stage upon which a specimen is to be situated for microscopic/spectrometric analysis. The sample stage is positioned such that the signal from the light sensor is maximized, thereby indicating good alignment between the sample stage and spectrograph. Additionally, the microscope sample stage bears a light source which can emit light to be detected by a light sensor situated at the vantage point of a user/viewer utilizing the microscope, and such a light sensor can simply take the form of a video camera or other image recordation unit associated with the microscope. The sample stage can also be positioned to optimize the signal at the light sensor to signify good alignment between the sample stage and the microscope.

Abstract: A spectrometer generates Vibrational Circular Dichroism (VCD) measurements having an exceedingly high signal-to-noise ratio, as well as a greater wavelength range over which measurements may be accurately provided. This is achieved by utilizing reflective optics (preferably solely reflective optics, i.e., no refractive elements) to supply a concentrated and collimated input light beam to a sample within a sample cell, and similarly collecting the light output from the sample cell via reflective optics for supply to a detector.

Abstract: In a spectrometer, preferably in a spectrometric microscope, light from a specimen is collected at a collector objective element and delivered to a camera element, which in turn provides the light to a photosensitive detector. A focal plane is provided between the collector objective element and the camera element, and one or more aperture arrays may be situated in the focal plane to restrict the detector's field of view of the specimen to the areas within the apertures. By utilizing aperture arrays with apertures of different sizes and shapes, the spatial resolution of the spectrometer readings may be varied without the need to vary the optics of the spectrometer. As a result, if the optics are optimized to minimize vignetting, spatial resolution may be varied without adverse increases in vignetting.

Abstract: An analytical microscope provides both UV fluorescence imaging and spectroscopic analysis of a sample with use of the same light collection element (objective lens or other optical element). An incident UV light beam travels to the sample via a dark field illumination path about the periphery of the collection lens, with the collection lens then collecting the emitted light from the sample and forwarding it to an eyepiece and/or camera for viewing. The sample is also illuminated with a laser through the collection lens to generate Raman emissions, which are then collected through the same collection lens and provided to a spectrograph for wavelength identification. Use of the same collection lens for both imaging and spectroscopic analysis better ensures that any imaged regions of interest on the sample are the same as those being spectroscopically analyzed.

Abstract: In an analytical instrument having a radiation detector, such as an electron microscope with an X-ray detector, a thermoelectric element (such as one or more Peltier junctions) is driven by a cooling power supply to cool the detector and thereby decrease measurement noise. Oil condensates and ice can then form on the detector owing to residual water vapor and vacuum pump oil in the analysis chamber, and these contaminants can interfere with measurement accuracy. To assist in reducing this problem, the thermoelectric element can be powered in the reverse of its cooling mode, thereby heating the detector and evaporating the contaminants. After the detector is cleared of contaminants, it may again be cooled and measurements may resume. Preferably, the thermoelectric element is heated by a power supply separate from the one that provides the cooling power, though it can also be possible to utilize a single power supply to provide both heating and cooling modes.

Abstract: An optical probe for use in infrared, near infrared, Raman, and other spectrometers includes a probe outer surface with a cavity defined therein. The probe emits light into a sample via emission locations on the probe outer surface, at least one being in the cavity. The light emitted into the sample is then collected at collection locations which include at least two of (a) a reflectance collection location situated on the probe outer surface for collecting diffusely reflected light from any adjacent sample; (b) a transmittance collection location situated in the cavity and receiving light transmitted across the cavity from an emission location situated on an opposite side of the cavity; and (c) a transflectance collection location situated in the cavity and receiving transflected light emitted from an emission location in the cavity, with such light being reflected from a side of the cavity opposite the transflectance collection location.

Abstract: A monochromator for use in a spectrograph admits light from an aperture to a primary reflector (preferably an off-axis parabolic mirror) which collimates the input light with low aberration and directs it to a diffraction grating. The component wavelengths of the input light are then directed to first and second secondary reflectors (preferably spherical or toroidal mirrors), which are chosen to cooperatively focus the component wavelengths in ordered bands across an array detector while each at least substantially cancels the effects of any aberrations introduced by the other. By choosing optical elements which supply the grating with input light with low aberration, and then choosing optical elements which receive the component wavelengths from the grating and which offset any aberrations introduced by the other receiving optical elements, wavelength resolution at the detector can be enhanced.

Abstract: An X-ray detector using a semiconductor detector, most preferably a Silicon Drift Detector, utilizes a field effect transistor or other voltage-controlled resistance to generate an output voltage proportional to its input charge (which is generated by the X-ray photons incident on the semiconductor detector). To keep the charge (and thus the output voltage) to an acceptable range—one wherein the relationship between output voltage and input charge is substantially proportional—a feedback circuit is provided between the output and input terminals, wherein the charge on the input terminal is depleted when the output voltage begins leaving the desired range. Preferably, this is done by a comparator which monitors the output voltage, and provides a reset signal to the input terminal when it begins moving out of range. Alternatively or additionally, the reset signal may be a pulse supplied to the input terminal from a pulse generator activated by the comparator.

Abstract: A spectrometer (100) includes a light source (102) providing output light (106) to the bundled input ends (108) of multiple light pipes (110). The light pipes (110) branch into sets (118) between their input ends (108) and output ends (114), with each set (118) illuminating a sample detector (126) (via a sample chamber (122)) for measuring light scattered or emitted by a sample, or a reference detector (128) for obtaining a reference/datum measurement of the supplied light, so that comparison of measurements from the sample detector (126) and the reference detector (128) allows compensation of the sample detector measurements for drift. Efficient and accurate measurement is further assured by arraying the multiple light pipes (110) in each set (118) about the input bundle (116) so that each set receives at least substantially the same amount of light from the light source (102).

Abstract: A spectroscopic microscope allowing both molecular spectrometry and visible microscopy of a sample has a light source for its spectrometer which provides Koehler illumination of the sample, i.e., light from points on the light source is projected across an area of the sample, as opposed to directly projecting an image of the light source onto the sample (as with critical illumination). However, the device may be adjusted to alternatively provide critical illumination of the sample, which is useful where spectrometric readings are to be obtained from a smaller area of the sample.

Abstract: Spectra obtained from spectrographic readings from a sample can be filtered for artifacts, e.g., distorted data points arising from cosmic ray interference, by subtracting one spectrum from another to obtain a difference spectrum; smoothing the difference spectrum; and then calculating the difference between the smoothed and unsmoothed difference spectra to obtain a noise spectrum. The resulting noise spectrum, which represents localized differences between the original spectra, can then be reviewed for readings which exceed the norm by some predetermined amount (e.g., readings which exceed the average level of the noise spectrum by some percentage). These excessive readings constitute distorted data points, and the corresponding points on the spectra can have their values adjusted to eliminate the excessive readings, thereby removing the artifacts.