Kaiser Optical Systems Inc.

Michael J Pelletier

Joseph B Slater

Harry Owen

Mark Welch

A method of monitoring sample crystallization from a solution. The method includes the collection of multiple Raman spectra from a sample dissolved in a solvent as a function of time and under conditions promoting crystallization. Within each of the multiple Raman spectra, a first signal is identified corresponding to the sample associated with the solvent. A second signal corresponding to the sample in a microcrystallite state is also identified. Thereafter, the intensity of the multiple Raman spectra are measured for an increase relating to formation of the sample in a microcrystallite state. A method of monitoring sample crystallization from a solution as a function of turbidity is also disclosed. The method includes the collection of multiple Raman spectra from a sample dissolved in a solvent as a function of time under conditions promoting crystallization. A decrease in intensity is measured across the multiple Raman spectrum over time, the intensity decrease associated with macroscopic crystallization opacity. The decrease in intensity is finely correlated with the onset of macroscopic crystallization of the sample from the solvent.

Raman spectroscopy crystallization analysis method

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.

Fiber-optic spectroscopic probe with reduced background luminescence

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.

Spectroscopic probe with leak detection

Methods and apparatus for synchronous spectral line imaging are disclosed for use in conjunction with any of a number of radiative analysis techniques such as Raman or fluorescence detection. Light emitted points on a sample are separated into wavelength components and directed onto a two-dimensional image sensor such that the wavelength components impinge along one dimension of the sensor. The other dimension of the sensor is used in conjunction with spatial position relative to the sample, with at least certain of the steps being repeated for the different sample points so as to form the spectral line image. In terms of apparatus, the invention preferably utilizes at least one optical fiber having an input end to receive the light emitted by the sample and an output end to deliver the emitted light to the two-dimensional image sensor. The use of a flexible optical fiber facilitates the movement of the light received from the sample, movement of the received light relative to the sensor, or both. A wavelength-separating optical element such as a diffraction grating is disposed between the output end of the optical fiber and the sensor. The image may represent a straight line on the sample, or it may be curved, intermittent or discontinuous.

Synchronous spectral line imaging methods and apparatus

Laser band-pass filter and/or band-reject filters are located at the end of an optical measurement probe by placing an appropriate Bragg grating proximate to the tip, and within, one or both of the optical fibers that make up the probehead. Thus, where an optical fiber is used to carry excitation energy of a nominal wavelength to a sample, the distal tip of this fiber will have included therein an optical filter to selectively pass energy of the nominal wavelength. Similarly, where an optical fiber is employed to carry stimulated emission from the sample to an analytical instrument such as a spectrometer, this fiber will have included within it at its distal tip an optical filter to selectively reject energy associated with the nominal wavelength. A disclosed system-level optical measurement probe would include a laser, a spectrometer, a first optical fiber to carry energy from the laser to a sample, including a Bragg grating laser bandpass filter at its tip, and a second optical fiber to carry energy collected from the sample to the spectrometer, including a Bragg grating laser band-reject filter at its tip.

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Saline, MI, United States of America

Michael J Pelletier