Abstract: An optical configuration suited to the monitoring of a process flow through the wall of a containment vessel for producing a high-quality, high-NA sample focus and reduced residual positive spherical aberration. The invention includes an optical path with a window extending through, and sealed to, the wall of the containment vessel, and an optical surface disposed in the optical path associated with minimizing aberration, increasing numerical aperture, or both. The window has a surface facing into the process flow and a surface facing away from the process flow and, the surface facing away from the process flow is associated with minimizing aberration or increasing numerical aperture. A lens is disposed outside the containment vessel and in the optical path, with the surface of the window facing the lens being substantially spherical. With such an arrangement, the light rays of the optical path are generally normal to the surface of the window facing the lens.

Abstract: In an optical measurement probe of the type which incorporates a window configuration suited to on-line process control and other applications this invention provides an improved technique for bonding such a window to probe body or process vessel. In general terms, the improvement arises through the use of a compression ring around the bonding area to maintain a consistent seal. In terms of apparatus, a hollow probe body terminates in a distal end having a flanged portion with an inner and outer wall that extends back into the body. The outer wall of the window is sealed against the inner wall of the flanged portion, with compression material urged against the outer wall of the flanged portion to pressurize the seal between the window and the inner wall of the flanged portion. In the preferred embodiment, the compression material is ring-shaped and exhibits substantially the same thermal expansion coefficient as the window.

Abstract: An improved optical configuration suited to the monitoring of a process flow through the wall of a containment vessel is capable of producing a high-quality, high-NA sample focus that outperforms current options. One advantage is reduced residual positive spherical aberration to minimize window signal contamination. The invention broadly includes an optical path with a window extending through, and sealed to, the wall of the containment vessel, and an optical surface disposed in the optical path associated with minimizing aberration, increasing numerical aperture, or both. The window has a surface facing into the process flow and a surface facing away from the process flow and, according to one configuration, the surface facing away from the process flow is associated with minimizing aberration or increasing numerical aperture. One optical arrangement includes a lens disposed outside the containment vessel and in the optical path, with the surface of the window facing the lens being substantially spherical.

Abstract: Disclosed is a method of positioning a focused image within a sampled medium in an optical measurement probe of the type wherein a focused sampling image is transmitted through a window having a surface facing a sampled medium. A test medium is measured, preferably through the window, and the magnitude of an optical signal associated with the test medium is then compared to the magnitude of an optical signal associated with the window, and the result of the comparison is used to position the focused image. Typically, the magnitudes of optical signals are representative or Raman scattering or another wavelength-selective radiative sampling process such as fluorescence detection. The method is not limited in terms of window composition, and is compatible with sapphire windows commonly used in industry. Nor is the invention limited in terms of test medium though, in the preferred embodiment a fluid hydrocarbon such as isopropyl alcohol is used.

Abstract: Reliable and economical passive thermal compensation in both focus (parallel to the optical axis) and lateral position (perpendicular to the optical axis) is disclosed for optical apparatus, including spectrographs. In the preferred embodiment, to maintain the position of the lens along the optical axis, two or more polymer spacers are used between the lens mount and a floating flange to which the lens is attached. The polymer spacers have a thermal coefficient of expansion such that when the temperature increases the lens is moved toward the detector array by the spacers to compensate for the normal increase of the lens-detector spacing with temperature. Flexure mounts, which bend by a predetermined amount in a known direction when the temperature changes, are preferably used to connect the lens mount to the floating plate, thereby moving the lens in a direction lateral to the optical axis.

Abstract: A method and apparatus for encapsulating optical elements, particularly dichromated gelatin (DGC) holographic optical elements (HOEs), exhibits a very high degree of environmental integrity. In broad terms, the optical element is disposed between opposing plates, and a metal seal soldered to the edge(s) of the plates to seal the optical element therewithin. In the preferred embodiment, the metalization includes chrome and nickel, or alloys thereof, followed by gold or platinum. The metallization is preferably applied using a low-temperature process such as vacuum deposition or sputtering. The metal seal may be in the form of a foil or wire. One or both of the plates are compatible with wavelengths of interest, and the technique may be used in transmissive and reflective configurations.

Abstract: A remote optical measurement suitable for Raman and fluorescence detection uses one or more dielectric components and an optical configuration which affords significant miniaturization, in some cases resulting in a probe with dimensions on the order of one-half inch or less on a side. A primary application is the pharmaceutical market, wherein the reactors vessels are only 1-inch in diameter, causing a scale down of instrumentation due to space requirements.

Abstract: Various optical probe configurations are particularly suited to the monitoring of a process flow through the wall of a containment vessel. A probe body extends through, and is sealed to, the wall of the containment vessel. The probe body has an inner wall terminating in a distal end with a window, enabling light from the process flow to pass therethrough and into the probe body. In one embodiment, one or more lenses are disposed within the probe body to focus the light into a focal point, and a restriction of the inner wall of the probe body is used to create a narrow aperture at the focal point. In an alternative embodiment, a plug transparent to the light of interest is sealed to the inner wall of the probe body. As a further alternative, the elements include a second window creating a cavity with the distal window, and a port into the cavity accessible from outside the window for sampling purposes.

Abstract: In an optical measurement probe of the type which incorporates a window configuration suited to on-line process control and other applications this invention provides an improved technique for bonding such a window to probe body or process vessel. In general terms, the improvement arises through the use of a compression ring around the bonding area to maintain a consistent seal. In terms of apparatus, a hollow probe body terminates in a distal end having a flanged portion with an inner and outer wall that extends back into the body. The outer wall of the window is sealed against the inner wall of the flanged portion, with compression material urged against the outer wall of the flanged portion to pressurize the seal between the window and the inner wall of the flanged portion. In the preferred embodiment, the compression material is ring-shaped and exhibits substantially the same thermal expansion coefficient as the window.

Abstract: Disclosed is a method of positioning a focused image within a sampled medium in an optical measurement probe of the type wherein a focused sampling image is transmitted through a window having a surface facing a sampled medium. A test medium is measured, preferably through the window, and the magnitude of an optical signal associated with the test medium is then compared to the magnitude of an optical signal associated with the window, and the result of the comparison is used to position the focused image. Typically, the magnitudes of optical signals are representative or Raman scattering or another wavelength-selective radiative sampling process such as fluorescence detection. The method is not limited in terms of window composition, and is compatible with sapphire windows commonly used in industry. Nor is the invention limited in terms of test medium though, in the preferred embodiment a fluid hydrocarbon such as isopropyl alcohol is used.

Abstract: A bulkhead-style connector incorporates a fixed, split sleeve to accurately and repeatably position a fiber-optic ferrule with respect to a housing. The split sleeve, which may be made of metal or ceramic, is attached in a manner allowing the sleeve to slightly expand. This allows the sleeve to locate the ferrule precisely, while still providing a controlled insertion and extraction force in the presence of a low level of contaminants. The split sleeve may be accurately located either by bonding it tangentially in a manner that enables the sleeve to expand, or by surrounding the sleeve with a material having a low modulus of elasticity enables the sleeve to expand. As a further option the sleeve may be bonded in a localized area and surrounded with low-modulus material elsewhere to provide a bonded and sealed configuration.

Abstract: Indicator light apparatus and methods associated with a laser beam having a primary wavelength enable an operator to see the indicator while wearing protective eyewear tuned to the primary wavelength. The apparatus includes a source of indicator light other than the primary wavelength, a first optical element for co-injecting the indicator light into the laser beam to form a co-propagating beam, and an optical or physical configuration enabling an operator to view light from the co-propagating beam. The first optical element may be some form of beam splitter or combiner, and the configuration enabling an operator to view light from the co-propagating beam uses a diffuser upon which the co-propagating beam impinges. The indicator light is preferably derived from an inexpensive source, such as a diode laser operating in the 670-690 nm range.

Abstract: Methods and apparatus are disclosed for calibrating remote optical probe configurations of the type wherein a spectrum emitted by a sample is delivered to a spectrograph for analysis using fluorescence, Raman detection or other dispersive techniques. The invention may be used to calibrate the spectrograph wavelength axis, the system spectral response or intensity axis, and the wavelength of the laser used for excitation. A collection optical fiber having a first end for receiving wavelengths emitted by the sample has a second end for delivering the wavelengths to a base unit containing the spectrograph. A calibration optical fiber is used to deliver an optical calibration signal to a point proximate to the first end of the collection optical fiber, and an optical element is used to direct the optical calibration signal into the collection optical fiber so that the spectrograph receives both the wavelengths emitted by the sample and the optical calibration signal.

Abstract: Various optical probe configurations are particularly suited to the monitoring of a process flow through the wall of a containment vessel. A probe body extends through, and is sealed to, the wall of the containment vessel. The probe body has an inner wall terminating in a distal end with a window, enabling light from the process flow to pass therethrough and into the probe body. In one embodiment, one or more lenses are disposed within the probe body to focus the light into a focal point, and a restriction of the inner wall of the probe body is used to create a narrow aperture at the focal point. In an alternative embodiment, a plug transparent to the light of interest is sealed to the inner wall of the probe body. As a further alternative, the elements include a second window creating a cavity with the distal window, and a port into the cavity accessible from outside the window for sampling purposes.

Abstract: In an improved optical switch, light from an input optical fiber is directed to one of a plurality of output optical fibers on a selective basis. The output fibers are contained in a bundle, preferably within a removable connector, thereby easing removal and maintenance. The input fiber also preferably forms pair of a bundle within a removable connector. The means for selectively directing the light from the end of the input fiber to the end of one of a plurality of the output fibers may include a pivot upon which at least the input optical fiber is mounted, or an electro-optic Bragg cell without moving parts. One or more lenses are preferably used between the end of the input optical fiber and the ends of the output fibers to assist in directing the light. A preferred arrangement incorporates two lenses, positioned so that the end of the output fiber and the end of a selected input fiber are each located at the focal point of one of the lenses.

Abstract: An optical-fiber breakage detection system continuously monitors the integrity of a laser-guiding fiber, whether the laser itself is on or off. If an interruption is detected, the system may cut off, lock out, or reduce laser power, as appropriate. An optical element such as a beamsplitter is used to introduce an optical test signal into one end of the fiber so that the signal is carried by the fiber to the other end where the test signal is detected and employed to perform a desired function. In the preferred embodiment, the test signal is modulated and encoded to minimize false shut-downs. The source of the optical test signal is preferably disposed at the first location and carried by a second fiber to the remote location, enabling the test signal to be compared directly to the test signal as detected.

Abstract: In an optical measurement system of the type wherein a source of excitation radiation is directed along an excitation path to stimulate an optical emission from a sample along a collection path, the use of polarization-based beam splitting enables optical shutters to control selective polarization of the excitation and/or collection paths while maximizing overall optical alignment accuracy. In a preferred embodiment, polarization-based beam-splitting optics are disposed in one or both of the excitation and collection paths to divide that path into two orthogonally polarized paths, and a controllable optical blocking element is disposed in at least one of the orthogonally polarized paths, such that control of over transmission of that path results in control over polarization.

Abstract: Calibration wavelengths are injected into an optical detection system preferably at a point after laser rejection filtration, enabling the known spectral content of the calibration radiation to pass through and into a spectrograph. In a preferred embodiment, at least some of the wavelengths used for calibration are derived through the excitation of a noble gas such as neon, thereby conveniently and economically providing a full-spectrum calibration line set. The feed from the laser source used to illuminate the sample is also preferably introduced into the collection path, enabling both the calibration wavelengths and laser line to be detected and used in calibration. The invention is applicable to spectral analysis systems in general, including non-Raman systems and systems which do not require a laser notch pre-filter stage.

Abstract: A fiber-optic spectroscopic probe minimizes unwanted sources of luminescence through the use of one or more non-luminescing beam-redirecting elements operative to aperture share the optical collection path. Preferably, the beam-redirecting element is reflective, and may take the form of a spot mirror on an otherwise optically transparent window to fold at least a portion of the excitation radiation into the optical collection path or a mirror having a centralized aperture may be used to introduce the excitation radiation into the optical collection path. In either case, the excitation radiation may first pass through a dispersive element in a bandpass filter configuration. Several complete fiber-optic-based probe head designs are disclosed along with results indicating reduced luminescence, spurious fluorescence, in particular.

Abstract: An optical probe assembly, which may be used with or without optical fibers for remote operation, incorporates a leak-detecting capability. A source such as a laser is used for optically exciting at least a portion of a sample substance, causing wavelengths characteristic of the sample to be emitted along a collection path for reception by spectral analysis means. The same laser or a different source is employed for optically exciting a point within a test region, causing wavelengths characteristic of any substances contained or entering into the test region to merge with those of the sample within the collection path.