Using Polarization to Increase Contrast of Water OH Raman Scattering Relative to Fluorescence of Dissolved Organic Matter.

Environmental fluorescence measurements sometimes use water Raman scattering as an internal standard to compensate for path length, lensing effects, and turbidity. Fluorescent dissolved organic matter (FDOM) in water may interfere strongly with the measurement of this reference. However, fluorescence in fluid solution is largely unpolarized, while the OH stretching Raman band of water is always strongly polarized.

Filter Fluorometer Calibration Without the Fluorometer.

We recently described a lightweight, low-power, waterproof filter fluorometer using a 180° backscatter geometry for chlorophyll-a (chl-) detection. Before it was constructed it was modeled to ensure it would have satisfactory performance. This manuscript repeats the modeling process that allows the calibration slope and detection limit for a fluorescent analyte in water to be estimated from system component performance and conventional spectrofluorometry alone.

Fluorometer Control and Readout Using an Arduino Nano 33 BLE Sense Board.

We describe the control and interfacing of a fluorometer designed for aerial drone-based measurements of chlorophyll- using an Arduino Nano 33 BLE Sense board. This 64 MHz controller board provided suitable resolution and speed for analog-to-digital (ADC) conversion, processed data, handled communications via the Robot Operating System (ROS) and included a variety of built-in sensors that were used to monitor the fluorometer for vibration, acoustic noise, water leaks and overheating. The fluorometer was integrated into a small Uncrewed Aircraft System (sUAS) for automated water sampling through a Raspberry Pi master computer using the ROS.

Chlorophyll Fluorometer for Intelligent Water Sampling by a Small Uncrewed Aircraft System (sUAS).

We describe a waterproof, lightweight (1.3 kg), low-power (∼1.1 W average power) fluorometer operating on 5 V direct current deployed on a small uncrewed aircraft system (sUAS) to measure chlorophyll and used for triggering environmental water sampling by the sUAS.

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) detection limits for blood on fabric: Orientation and coating uniformity effects.

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to analyze four types of forensically relevant fabrics coated with varying dilutions of blood. The blood was applied in two manners, dip coating with a smooth and uniform layer and drip coating with droplets from pipettes. Spectra of neat and dip coated fabrics were acquired using controlled orientations, and these were compared to spectra collected on samples with random orientations.