An example CO.sub.2 monitoring systems is configured for monitoring levels of CO.sub.2 in a wellbore. A CO.sub.2 monitoring system may include one or more laser monitoring tools. A laser monitoring tool may include an optical element to output a laser beam, a detector to receive the laser beam, a first chamber housing the optical element and detector, and a second chamber including an inlet and an outlet receive and release, respectively, wellbore fluid. The first chamber may be in fluid connection with second chamber via a gas permeable membrane. Gas may permeate from second chamber into first chamber. Gas in the first chamber is subjected to a laser beam. Absorption of light by the gas is measured, and content of gas is determined based at least in part on the amount of light absorption by the gas.

An example CO.sub.2 monitoring systems is configured for monitoring levels of CO.sub.2 in a wellbore. A CO.sub.2 monitoring system may include one or more laser monitoring tools. A laser monitoring tool may include an optical element to output a laser beam, a detector to receive the laser beam, a first chamber housing the optical element and detector, and a second chamber including an inlet and an outlet receive and release, respectively, wellbore fluid. The first chamber may be in fluid connection with second chamber via a gas permeable membrane. Gas may permeate from second chamber into first chamber. Gas in the first chamber is subjected to a laser beam. Absorption of light by the gas is measured, and content of gas is determined based at least in part on the amount of light absorption by the gas.

The present disclosure describes a method and apparatus of measuring dynamic light scattering of a sample. In an embodiment, the apparatus includes a platen, a light source underneath the platen and configured to emit emitted light through the platen and into the sample, collector optics underneath the platen and configured to capture scattered light, and an optical absorber configured to be in contact with the sample, configured to absorb transmitted light, and configured to redirect reflected light away from the collector optics. In an embodiment, the method includes depositing a sample on a platen, emitting emitted light from a light source underneath the platen through the platen and into the sample, capturing via collector optics underneath the platen scattered light, contacting the sample with an optical absorber, absorbing via the absorber transmitted light, and redirecting via the absorber reflected light away from the collector optics.

The present disclosure describes a method and apparatus of measuring dynamic light scattering of a sample. In an embodiment, the apparatus includes a platen, a light source underneath the platen and configured to emit emitted light through the platen and into the sample, collector optics underneath the platen and configured to capture scattered light, and an optical absorber configured to be in contact with the sample, configured to absorb transmitted light, and configured to redirect reflected light away from the collector optics. In an embodiment, the method includes depositing a sample on a platen, emitting emitted light from a light source underneath the platen through the platen and into the sample, capturing via collector optics underneath the platen scattered light, contacting the sample with an optical absorber, absorbing via the absorber transmitted light, and redirecting via the absorber reflected light away from the collector optics.

A method of measuring the concentration of a gas in a target environment using a laser lidar system, comprises directing a laser beam towards an environment containing the gas, tuning the laser wavelength over a wavelength range including the absorption line of the gas, and measuring intensity of laser light returned from the environment containing the gas, as a result of scattering as a function of time. The intensity vs time is then converted into gas absorption vs wavelength, and the gas absorption vs wavelength is used to determine the concentration of the gas in the target environment.

A method of measuring the concentration of a gas in a target environment using a laser lidar system, comprises directing a laser beam towards an environment containing the gas, tuning the laser wavelength over a wavelength range including the absorption line of the gas, and measuring intensity of laser light returned from the environment containing the gas, as a result of scattering as a function of time. The intensity vs time is then converted into gas absorption vs wavelength, and the gas absorption vs wavelength is used to determine the concentration of the gas in the target environment.

A simple optical layout for a grazing angle probe mount that allows coupling to a mid-infrared (MIR), laser-based spectrometer is provided. The assembly enables doing reflectance measurements at high incident angles. In the case of optically thin films and deposits on MIR reflective substrates, a double pass effect, accompanied by absorption by the chemicals or biological samples deposited in an Infrared Reflection-Absorption Infrared Spectroscopy (IRRAS) modality is achieved. The optical system includes a probe that allows the passage of MIR light through the same sampling area twice. Initially, the infrared beam produces a spot on the surface, and then the light is returned in back reflection to the sample surface producing a new little slightly larger spot onto the selfsame position.

Improved gas leak detection from moving platforms is provided. Automatic horizontal spatial scale analysis can be performed in order to distinguish a leak from background levels of the measured gas. Source identification can be provided by using isotopic ratios and/or chemical tracers to distinguish gas leaks from other sources of the measured gas. Multi-point measurements combined with spatial analysis of the multi-point measurement results can provide leak source distance estimates. These methods can be practiced individually or in any combination.

Improved gas leak detection from moving platforms is provided. Automatic horizontal spatial scale analysis can be performed in order to distinguish a leak from background levels of the measured gas. Source identification can be provided by using isotopic ratios and/or chemical tracers to distinguish gas leaks from other sources of the measured gas. Multi-point measurements combined with spatial analysis of the multi-point measurement results can provide leak source distance estimates. These methods can be practiced individually or in any combination.

Chalcogenide waveguides with high width-to-height aspect ratios and a smooth exposed surfaces can serve as mid-infrared evanescent-absorption-based sensors for detecting and identifying volatile organic compounds and/or determining their concentration, optionally in real-time. The waveguide sensors may be manufactured using a modified sputtering process in which the sputtering target and waveguide substrate are titled and/or laterally offset relative to each other and the substrate is continuously rotated.