Abstract: A method for precision thermal measurement and control, especially for bioreactors, as well as the correction of temperature sensitive probes such as pH and dissolved oxygen. Typical control requirements are +/?0.1° C. The thermal measurement circuit converts a sensor output to a high level voltage or current with great accuracy and provides noise immunity and sensor isolation. While digital outputs from sensor converters can have the greatest noise immunity, the noise associated with digital circuitry may contaminate low level sensor signals so in many cases an analog sensor converter is preferred because of low noise generation, especially if the converter is near the sensor. The circuit is low cost, reliable, generates minimal heat is immune to, and does not generate noise, and requires minimal calibration effort.

Abstract: A port for use with a bioreactor vessel comprising: i) a base member comprising a hollow tubular portion and a base plate configured to be sealingly affixed to a hole in the wall of a bioreactor vessel ii) a hollow, generally tubular bushing member for containing electrical, optical, microfluidic and/or chemical monitoring components which bushing member fits inside the bore of the tubular portion of the base member, both the base member and bushing member providing access to the contents of a bioreactor by; iii) a monitoring assembly inserted into the bushing member which assembly comprises means for providing incoming optical and/or electrical signals and means for collecting and transmitting measurement signals resulting from the interaction of incoming optical and/or electrical signals with the contents of a bioreactor; and iv) a cover which maintains the position and alignment of components ii) and iii) relative to the base member.

Abstract: A validation apparatus for testing the measurement accuracy of a phase fluorimeter comprising: i) a photodetector responsive to the excitation light emitted by a phase fluorimeter; ii) electronics connected to the detector which calculates the phase of the light emitted by the phase fluorimeter and causes a light source in the validation apparatus to emit light of a wave length which will stimulate the detector of the phase fluorimeter but which is phase shifted relative to the light emitted by the phase fluorimeter.

Abstract: A port assembly for use with a polymeric bioreactor bag includes the following components: i) a hollow port member made from a material which can be fusibly affixed to the wall surface of the bioreactor bag; ii) at least one fluorophore spot positioned on the port member; iii) a conduit for conveying excitation light from an optical source to the fluorophore, which conduit can be a lens, a curved parabolic collimator, a shaped reflector or a wave guide; and iv) a second conduit for conveying fluorescent emission light from the excited fluorophore to a photo-detector, which second conduit although different from the first, can likewise be a lens, a curved parabolic collimator, a shaped reflector or a wave guide.

Abstract: A system and method for analyzing a target analyte gas concentration using a photoacoustic spectroscopy cell comprising: i) a modulatable light source which provides optical radiation at an absorption wavelength of a target analyte; ii) a resonant acoustic chamber for containing said analyte; iii) a microphone positioned within said chamber whereby the acoustic reactance of the microphone is a substantial factor in determining the acoustic resonant frequency of the acoustic chamber and where the magnitude of the acoustic reactance of the microphone is at least two times the acoustic resistance of the microphone.

Abstract: An optical loss probe utilized as a bioreactor process monitor manifesting a substantially linear response in optical loss vs. concentration of scatterers present in an aqueous medium in the range of between about 0 AU and about 4.0 AU, said probe comprising: i) a light source, ii) an optical detector, and iii) an optical gap between said light source and said optical detector, said optical detector having a receiving aperture configured such that the solid angle of acceptance of the light passing through said optical gap and impinging on said optical detector is less than ?/50 radians.

Abstract: An apparatus and method for the stimulation and collection of fluorescent signals from a target analyte. The apparatus comprises: i) a frequency modulated optical source which emits excitation light of a wavelength which will stimulate a target fluorophore to emit a fluorescent signal when illuminated by the excitation light, ii) a first optical filter interposed between the optical source and the target fluorophore, iii) a second optical filter interposed between the fluorophore and a photo-detector and positioned to receive the emitted fluorescent signal. The beam path of at least one, preferably both, of the excitation light and the fluorescent signal is transmitted substantially through free space. A data processor will normally be used to calculate and record the phase delay between the excitation light and the fluorescent signal.

Abstract: A method for compensating for changes in output power or wavelength of an optical source with temperature. Many optical sources have power and/or wavelength variations with temperature which can be compensated by open- or closed-loop methods if a method of accurately measuring the optical source temperature is available. The voltage across a semiconductor junction varies with temperature. Measuring the optical source power or wavelength variation with temperature and tracking the voltage across the semiconductor junction provides a means for compensating an instrument for temperature induced optical output power or wavelength variations. An important field of application is optical density or turbidity measurements in cellular media.

Abstract: A method for analyzing a target analyte gas concentration using a photoacoustic spectroscopy cell comprising: i) a modulatable light source which provides optical radiation at an absorption wavelength of a target analyte; ii) a resonant acoustic chamber for containing said analyte; iii) a microphone positioned within said chamber whereby the acoustic reactance of the microphone is substantially equal but opposite in value to the acoustic reactance of the chamber at a selected cell resonance frequency.

Abstract: An in-situ technique is provided for automatically verifying proper operation of a photometric device, such as a cell density probe (CDP). The CDP has a first detector and a second detector. The first detector senses light that is transmitted from a light source of the CDP. The second detector senses light that has passed through an optical gap at a tip of the CDP, wherein the sensed light has been reduced in intensity due to light absorption. Electrical current provided to the light source is reduced, and the resultant values of a light characteristic (such as intensity) are sensed. These values from the detectors are compared against one or more predicted values. If the CDP is operating properly, the values from the detectors will be consistent with the predicted values. If there is a malfunction in the CDP, then the values from the detectors will be inconsistent with the predicted values.

Abstract: A tunable laser and laser tuning method based on the use of a tunable etalon in reflection as a mirror within a laser cavity and forming an end reflective surface thereof. The laser emission wavelength is not necessarily at a wavelength of peak etalon reflectivity. A preferred embodiment makes use of a microelectromechanical etalon to tune an external cavity semiconductor.

Abstract: A tunable laser and laser tuning method based on the use of a tunable etalon in reflection as a mirror within a laser cavity. The laser emission wavelength is not necessarily at a wavelength of peak etalon reflectivity. A preferred embodiment makes use of a microelectromechanical etalon to tune an external cavity semiconductor laser.

Abstract: According to the present invention, laser performance is improved by appropriately matching the spectral periods of various etalons within the laser cavity. A first embodiment of the invention is a discretely tunable external cavity semiconductor laser where a grid fixing etalon is present in the laser cavity, the grid fixing etalon free spectral range (FSR) is a whole number multiple of the laser cavity FSR, and the grid fixing etalon FSR is a whole number multiple of the chip etalon FSR. A second embodiment of the invention is a fixed wavelength external cavity semiconductor laser where the chip etalon FSR is a whole number multiple of the laser cavity FSR, and a mode suppressing etalon is inserted into the laser cavity such that the mode suppressing etalon FSR is a whole number multiple of the chip etalon FSR. A third embodiment of the invention is a tunable external cavity semiconductor laser where the chip etalon FSR is a whole number multiple of the laser cavity FSR.

Abstract: Method and system for providing laser light that is tunable over a relatively wide mid-infrared wavelength range, such as 2-17 &mgr;m. A first noncritically phase matched nonlinear crystal receives a laser light beam and converts the light to a first cavity beam having a first selected wavelength, using optical parametric oscillation techniques. A second noncritically phase matched nonlinear crystal receives the first cavity beam and converts the light to a second cavity beam having a second selected wavelength. Where the first wavelength is tuned (e.g., by temperature change or effective path length change) over a wavelength range of 2-5 &mgr;m, the second wavelength can vary over a higher and broader wavelength range, such as 3-17 &mgr;m.

Abstract: A heat recoverable conductive polymeric tubular article shrinks radially when electrical current is passed therethrough. It is powered by elongate electrodes extending along the article along part of the length only of the article, thereby defining an inwardly directed electrode end material of the article preferably has specific electrical properties to compensate for the increased current density that would otherwise exist at the inwardly directed electrode end, and which could lead to burning or hot spot formation.

Abstract: A method for adding ester side groups, e.g. liquid crystalline groups, to a polymer backbone using tin chemistry. ##STR1## The method is particularly useful for adding side groups to a polymer that contains thermally sensitive groups, such as epoxy groups, as the reaction can be carried out at relatively low temperatures.Claims are to(a) a method of adding side units to a polymer;(b) a polymer containing the side units - SnBu.sub.3 ;(c) specific polymers.

Abstract: A tubular article comprises an electrically conductive polymeric material. The article increases in wall thickness on recovery. It can be used for example as a duct seal or as an internal coupler or seal for hollow conduits such as pipes. The article may have plain or convoluted walls.

Abstract: A tubular heat recoverable article comprises conductive polymeric material and is heated to effect recovery by the passage of electrical current therethrough. Elongate electrodes are attached on the surface or embedded in longitudinal flanges extending along the article. The flanges also comprise conductive polymeric material but are not heat recoverable, and therefore remain substantially undeformed on recovery other than bending to accommodate transitions. This means that the contact resistance between the electrode and the conductive material of the flange does not increase significantly on recovery.

Abstract: An article having a transparent conductive coating having predetermined interference reflectance and transmission properties substantially independent of its conductivity, comprising:(a) a substrate having a refractive index n.sub.0 and(b) a coating disposed over at least a portion of the substrate and consisting of:(i) at least one transparent dielectric layer having a refractive index n.sub.1 different from n.sub.0 ; and(ii) at least one transparent conductive layer having a refractive index substantially equal to n.sub.1, at least one of which has a thickness sufficient to provide a desired conductivity;the coating having a thickness such that it has predetermined interference reflectance and transmission properties substantially independent of its conductivity.