Abstract: A cavity enhanced absorption spectrometer (CEAS) and method for controlling the same. The CEAS includes a coherent electro-magnetic radiation source, an electro-magnetic modulator that creates a sideband with an adjustable frequency that is offset from the radiation source frequency by imparting an adjustable frequency modulation to the radiation. The CEAS also includes a RF source that drives the electro-magnetic modulator and a cavity enhanced absorption resonator (CEAR) that receives the sideband. A detector measures the proximity of the frequency of the sideband relative to the resonant frequency of the CEAR and generates a proximity detector signal, which is converted by a controller to a control signal that controls at least one of the RF source and the resonant frequency of the CEAR such that the frequency of the sideband and the resonant frequency of the CEAR are adjusted to maintain a predetermined proximity therebetween.

Abstract: T-sensor devices that include a main conduit that defines a diffusion space, at least a first and second supply conduit for conveying fluids into the main conduit, and at least one sensor having a sensing zone that extends into the diffusion space in a fixed location relative to the main conduit. The first and second supply conduits are separated by divider from which a diffusion interface extends into the diffusion space. In order to capture sensing information without employing moving the physical location of sensors or employing more sensors, devices according to the invention alter a location of a diffusion interface extending into the diffusion space from a diffusion start point on the divider relative to the sensing zone of the at least one sensor, without altering the fixed location of the sensor relative to the main conduit. Methods of sensing properties of fluids and analytes are also disclosed.

Abstract: A chromatography sensor device is provided that includes a first loading chamber into which a sample fluid can be inserted, a second loading chamber into which a buffer fluid can be inserted, a diffusion column adapted to communicate with the first loading chamber and the second loading chamber and having walls lined with a chromatography stationary phase, a first high finesse optical cavity communicating with the diffusion column at a first distance from the gate, a second high finesse optical cavity communicating with the diffusion column at a second distance from the gate; and one or more lasers for generating laser frequencies for exciting the first and second high finesse optical cavities, whereby the sample fluid may diffuse into the diffusion column containing the buffer fluid and the one or more lasers and associated detectors may be used to detect a molecule of interest in the sample fluid.

Abstract: A method and device for measuring trace levels of particles in an air sample is described. A device operating in a gradiometer configuration with two cavities built from a monolithic structure and utilizing a single probe laser, provides common mode subtraction of acoustic, vibrational, laser intensity and other noise sources, which allows sensitivity more closely approaching the quantum limit. Differential measurements between the two cavities occur simultaneously, which reduces errors due to cavity drift. Absorptive gradiometry can therefore provide noise immune detection for trace gasses, including broad linewidth absorbers where frequency-noise immune schemes are not practical. Differential measurements can be used for background subtraction, sensing vapor plum gradients and determining vapor plume propagation direction.

Abstract: A method and device for measuring trace levels of particles in an air sample is described. A device operating in a gradiometer configuration with two cavities built from a monolithic structure and utilizing a single probe laser, provides common mode subtraction of acoustic, vibrational, laser intensity and other noise sources, which allows sensitivity more closely approaching the quantum limit. Differential measurements between the two cavities occur simultaneously, which reduces errors due to cavity drift. Absorptive gradiometry can therefore provide noise immune detection for trace gasses, including broad linewidth absorbers where frequency-noise immune schemes are not practical. Differential measurements can be used for background subtraction, sensing vapor plume gradients and determining vapor plume propagation direction.