Pendar Technologies, LLC

Tobias Mansuripur

Daryoosh Vakhshoori

Romain Blanchard

Masud Azimi

Peili Chen

Arran M Bibby

Fred R Huettig, Iii

Gokhan Ulu

Greg Vander Rhodes

Kalyani Krishnamurthy

A compact, portable Raman spectrometer makes fast, sensitive standoff measurements at little to no risk of eye injury or igniting the materials being probed. This spectrometer uses differential Raman spectroscopy and ambient light measurements to measure point-and-shoot Raman signatures of dark or highly fluorescent materials at distances of 1 cm to 10 m or more. It scans the Raman pump beam(s) across the sample to reduce the risk of unduly heating or igniting the sample. Beam scanning also transforms the spectrometer into an instrument with a lower effective safety classification, reducing the risk of eye injury. The spectrometer's long standoff range automatic focusing make it easier to identify chemicals through clear and translucent obstacles, such as flow tubes, windows, and containers. And the spectrometer's components are light and small enough to be packaged in a handheld housing or housing suitable for a small robot to carry.

Methods and devices for standoff differential Raman spectroscopy with increased eye safety and decreased risk of explosion

Methods and devices for standoff differential Raman spectroscopy decreased risk of explosion

We present here systems and methods for generating a heterodyne signal using the naturally occurring chirp of a pulsed single-mode laser. The electrical square-wave pulse used to drive the laser heats the laser cavity, causing the laser frequency to change or chirp during the emission of the optical pulse. This chirped optical pulse can be split into a chirped signal pulse that interacts with a sample and a chirped reference pulse that interferes with the chirped signal pulse on a detector to produce a heterodyne modulation whose instantaneous phase and amplitude depend on the sample's dispersion and absorption, respectively. The chirp is reproducible, so the heterodyne modulation, instantaneous phase, and/or instantaneous amplitude can be average over many measurements, either with multiple pulses from the same laser or multiple pulses from different lasers, each emitting at a different wavelength.

Devices and methods for coherent detection using chirped laser pulses

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Cambridge, MA, United States of America

Tobias Mansuripur