In vivo imaging of the human eye using a 2-photon-excited fluorescence scanning laser ophthalmoscope.

BackgroundNoninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, are highly sensitive to UV light; thus, safe analyses of these processes in humans are currently beyond the reach of even the most modern ocular imaging modalities.MethodsWe present a compact, 2-photon-excited fluorescence scanning laser ophthalmoscope and spectrally resolved images of the human retina based on 2-photon excitation (TPE) with near-infrared light.

Compact, spherical mirror-based dense astigmatic-like pattern multipass cell design aided by a genetic algorithm.

We propose a unique way to design multipass cells (MPCs), which combines cost-efficient spherical mirrors with the high-density pattern of astigmatic mirrors. Such functionality was accomplished using at least three standard spherical mirrors appropriately tilted, which breaks the parallelism between them. A genetic algorithm (GA) supported the cell configuration optimization.

Mid-Infrared Trace Gas Sensor Technology Based on Intracavity Quartz-Enhanced Photoacoustic Spectroscopy.

The application of compact inexpensive trace gas sensor technology to a mid-infrared nitric oxide (NO) detectoion using intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) is reported. A minimum detection limit of 4.8 ppbv within a 30 ms integration time was demonstrated by using a room-temperature, continuous-wave, distributed-feedback quantum cascade laser (QCL) emitting at 5.

Mid-infrared dual-gas sensor for simultaneous detection of methane and ethane using a single continuous-wave interband cascade laser.

A continuous-wave (CW) interband cascade laser (ICL) based mid-infrared sensor system was demonstrated for simultaneous detection of atmospheric methane (CH) and ethane (CH). A 3.337 µm CW ICL with an emitting wavenumber range of 2996.