Abstract: A transverse optical transmission probe having a probe body and a probe tip. The probe use optical fibers to both transmit radiation from an instrument to the probe tip and to return the sample affected radiation to the instrument. The fibers are in parallel and contained in the probe body. The probe tip includes two optical elements that protrude into the sample and are configured to define a sample gap so that incident radiation pass through the sample in a direction transverse to the axis to the probe and eventually reaches the receiving fiber. Each of the optical elements may be formed from a single piece of material or may be a composite formed by adhering two or more pieces of material together. One or more lensed surfaces may be used to cause the end of the transmitting fiber to be imaged on the end of the receiving fiber.

Abstract: A multi-pass gas cell that operates with reflected radiation pass through a gas, the reflected radiation transmitted and received by first and second fiber optic ports that are subject to an alignment adjustment, and a mirrored viewing window having a inner reflective surface exposed to an interior of the elongated cell body for reflecting the radiation within the cell body, an outer viewing surface, and a transmittance characteristic that permits a portion of the radiation to pass through the mirrored window, from the inner reflective surface to the outer viewing surface, as a visual indicator of the alignment condition of the reflected radiation relative to the first and second fiber-optic ports.

Abstract: A probe for use in Raman spectroscopy that can be inserted into a chemical vessel through a small diameter fitting while maximizing the amount of Raman shifted radiation collected and minimizing spurious effects.

Abstract: A multipass system for sampling by Raman spectroscopy enhances the collected signal and provides a system having improved sensitivity. The system incorporates an injection element for inserting collimated excitation radiation into an optical path, an objective lens for focusing the excitation radiation into the sample and for collecting radiation, a blocking filter that is substantially perpendicular to the optical path and that transmits Raman shifted radiation and reflects the excitation radiation, and a mirror for causing the excitation radiation to reflect excitation radiation back and forth between the mirror and the blocking filter multiple times while Raman shifted radiation is passed through the blocking filter for collection and analysis.

Abstract: The invention comprises a spectroscopic measuring device, a seal for such a device, and a method for sealing such a device. A window having a first and second portion is disposed in a cavity of a housing. The first portion is adjacent to an exterior of the device and has a first diameter less than a second diameter of the second portion, thus forming a shoulder therebetween and defining a gap between the first portion and an interior housing surface. An intermediate ring with a, metallic coating is disposed in the gap adjacent to the shoulder. A retaining ring is disposed in the gap adjacent to the intermediate ring. An exposed surface of the retaining ring is flush with an end housing surface and an exposed sapphire surface. A portion of the exposed retaining ring surface is electron beam welded to a portion of the end housing surface. The housing, intermediate ring, and retaining ring comprise a nickel-molybdenum-chromium alloy.

Abstract: The invention relates to a fiber-optic coupled diffuse reflectance probe that is adapted to detachably connect to a bifurcated fiber bundle. The probe includes a solid light guide for separating the bundle from the target within a small-diameter probe body. A probe of this construction is especially useful for analyzing high temperature and high pressure targets, through relatively small fittings, as is required in polymer extrusion applications. The solid light guide may extend along all or along a lesser portion of the probe body's length. Its fiber-end may be coupled directly to the illumination and detector fibers or indirectly, and at some distance from the fibers, by way of a lens or a hollow light guide. Its target-end may be exposed to terminate in a direct face-to-face relationship with the target, or it may be located behind an intermediate window. The solid light guide is characterized by a target-end refracting surface that minimizes stray light.

Abstract: A sample immersion probe is disclosed which has an ATR (attenuated total reflectance) element at its tip. The ATR is so shaped that radiation exiting the probe will travel in paths parallel to radiation entering the probe. The angles of incidence of radiation on the ATR surface (or surfaces) which permit partial absorption by the sample material are greater than 45.degree.. At least one of the ATR surfaces in contact with the sample has a fully reflecting coating which prevents radiation absorption by the sample at that location. The ATR shape may be symmetrical or non-symmetrical with respect to the axis of symmetry of the probe. The radiation entering the probe may be in a separate light guide (i.e., path) from the radiation exiting the probe; or the entering and exiting radiation may be in the same light guide (path).

Abstract: The invention relates to a fiber-optic coupled diffuse reflectance probe that is adapted to detachably connect to a bifurcated fiber bundle. The probe includes one or more lenses for imaging the bundle onto a target with more space between the bundle and the target than otherwise possible. The collecting lens adjacent to the bundle preferably has a reflection stop which diverts reflected light away from the bundle to minimize the problem of stray light. The preferred probe also uses an objective lens to increase the distance between the bundle and the target. The rays emerging from the collecting lens will diverge or spread because of the finite diameter of the transmitting fibers in the bundle.

Abstract: A sensing apparatus for spectral analysis in which the sensing head is bi-layered. The layer contacting the sample is formed of corrosion-resistant material, e.g., diamond. It is engaged by a supporting layer formed of infrared transparent material, e.g., zinc selenide through which radiation passes on its way to and from the sample-contacting layer. In order to avoid non-linearity in the sample absorbance results, incoming paraxial rays are all reflected in such a way that they are reflected at the same angle, and the same number of times, from the sample contacting surface of the corrosion resistant layer. The incoming rays may be reflected at a conical surface, or at a flat rooftop-like surface. The exiting rays are preferably reflected so that they are parallel to the incoming rays. Where a conical reflecting surface is used, it may be a surface of the zinc selenide layer, or a highly reflective surface provided by another element.

Abstract: An immersion probe (for powder or liquid) is disclosed comprising an ATR element supported at the bottom of a radiation-confining tube. The ATR element has a sample-entering tip which is either conical (preferably) or roof-top shaped. The ATR element causes entering radiation to be reflected twice by its sample-engaging surfaces, where attenuation due to the sample material occurs. The ATR element also acts as a retroreflector, causing the exiting radiation to follow a path parallel to the entering radiation. In order to avoid spurious results due to reflection by the rear surface of the ATR element, its rear surface is cone shaped or rooftop shaped, using a large apex angle.

Abstract: A sparging-infrared liquid analyzing system having a vessel in which a gas stream makes a single pass through a liquid stream containing contaminants, in order to provide vapor-to-liquid equilibrium of contaminants in the gas stream. The gas stream is then passed through a condenser, in which the gas temperature is precisely controlled, and the gas is cooled to a point below the dew point of water vapor in the gas stream. The gas is then flowed into a gas cell for infrared analysis. Water vapor effects are removed from the analytical output. Also, the effects of excessive depletion of relatively insoluble contaminants are removed from the analytical output.

Abstract: A probe for liquid sample analysis is disclosed which causes radiation to pass through the sample at a gap formed in the probe housing. A single radiation transmission is used to avoid problems of radiation back scatter and sample reliability. Windows are provided on opposite sand and and and and and and ides of the gap to accommodate the shape of the beam in the gap, which may either be collimated, or focused in the gap. A retroreflector may be used to reverse the radiation direction in the probe. The light to and from the probe is preferably transmitted by optical fiber cables. Within the probe, light guides other than optical fibers may be used.

Abstract: A method for determining the concentration of individual solutes in a body of liquid, e.g., measuring contaminants in waste water. A sparging IR process is used, in which gas in the form of minute bubbles moves upwardly in a non-flowing body of liquid. The gas remove vaporized samples of the subject solutes and flows to a gas cell, where it is subjected to infrared spectrometer analysis. The true concentration of each subject solute is measured by plotting its concentration values against elapsed time, and then extrapolating back to time zero to determine the initial concentration of the solute. In addition, the rate of depletion is used to determine the ratio of vapor pressure to solubility of the solute. Replotting the original data using logarithm values can simplify the extrapolation.

Abstract: A gas cell for use in spectrometric analysis is disclosed, in which a series of pipes provide both the gas chamber and a light guide for infrared radiation which passes through the gas to accomplish the analysis. The light pipe is designed to provide a maximum radiation throughput of a collimated radiation beam. The same pipe provides laminar gas flow into and out of the gas cell. In other words, the gas when moving is not obstructed or restricted by changes in the cross-sectional area of its passageway.

Abstract: A radiation guiding structure for incoherent radiation is disclosed in which a collimated beam is transmitted through a light pipe having high radition throughput. Radiation losses due to absorbance are minimized by: (1) matching the area of the beam and the light pipe passage; (2) minimizing the number of reflectances of a given ray by reducing the angular divergence of radiation in the beam; and (3) using a reflective coating on the wall of the light pipe which has the low point of its reflectance curve at a relatively high grazing angle.

Abstract: An ATR sample cell is disclosed, of the type incorporating a circular internal reflectance crystal. A flowing liquid sample has input and output ports in the IRE housing, or cell, which are offset from the axis of the circular IRE (or rod) sufficiently to direct the flow of liquid against the internal wall (usually stainless steel) of the flow jacket, rather than against the IRE. This tends to create a helical flow path from the input port at one end of the housing to the output port at the other end of the housing. In order to further control the sample flow path, and augment the spiraling effect, two further improvements are disclosed. The structure through which the sample material enters the sample chamber surrounding the IRE is designed to establish a spiraling motion of the liquid flow before it enters the sample chamber. Also, the inner cylindrical wall of the metal housing has a groove which forms a helical path from the input to the output end.

Abstract: A probe is disclosed for use in internal reflection spectroscopy at locations immersed in containers. Two parallel light pipes, located inside the probe, are used to carry radiation toward and away from an internal reflectance element (IRE) located at or near the bottom of the probe. The IRE, which is exposed to analyte in the container, has a radiation-entering surface and a radiation-exiting surface which permit collimated radiation to fill both light pipes. No beamsplitter is required to separate pre-sample and post-sample radiation. In one embodiment the IRE is a rod having concave conical entering and exiting surfaces, and a separate radiation-direction-reversing element is mounted on the tip of the probe. In another embodiment the IRE is itself a direction-reversing means mounted on the tip of the probe.

Abstract: An external reflectance spectroscopy apparatus and method are disclosed in which maximum radiation througput is obtained by using a beamsplitter which reflects half of a collimated beam and transmits the other half. In order to obtain reliable results, the condition of perpendicular incidence on the sample is approximated (without limiting throughput) by providing a beamsplitter having an uneven number of reflecting blades and the same number of transmitting openings. Each reflecting blade is opposite to an open area having the same size and shape. The result is a substantial equalizing of contributions from rays polarized parallel to the plane of incidence and from rays polarized perpendicular to the plane of incidence.

Abstract: An apparatus and method for fluid sample analysis are disclosed which use a cylindrical internal reflectance element (IRE) having conical end surfaces. The divergence of rays inside the IRE is minimized by using reflecting cones at each end of the IRE, the structural elements and their dimensions being such that each entering ray strikes the conical IRE end surface at substantially the same angle of incidence. Means are included for providing optical stops at the large end of both the input and output reflecting cones, in order to eliminate any rays which might travel through the IRE without first being reflected by the input cone. Using such stops and properly dimensioning the entering diameter of the reflecting cone, result in a system in which each ray entering the IRE has been reflected once, and only once, by the reflecting cone.

Abstract: A probe for use in Raman spectroscopy that can be inserted into a chemical vessel through a small diameter fitting while maximizing the amount of Raman shifted radiation collected and minimizing spurious effects.