Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications

Electronic And Thermally Tunable Infrared Metamaterial Absorbers

In this paper, we report a computational and experimental study using tunable infrared (IR) metamaterial absorbers (MMAs) to demonstrate frequency tunable (7%) and amplitude modulation (61%) designs. The dynamic tuning of each structure was achieved through the addition of an active material - liquid crystals (LC) or vanadium dioxide (VO2) - within the unit cell of the MMA architecture. In both systems, an applied stimulus (electric field or temperature) induced a dielectric change in the active material and subsequent variation in the absorption and reflection properties of the MMA in the mid- to long-wavelength region of the IR (MWIR and LWIR, respectively). These changes were observed to be reversible for both systems and dynamic in the LC-based structure

ASSIST- Automated System for Surgical Instrument and Sponge Tracking

Abstract — Every surgical item used during surgery (e.g., sponges) must be accounted for after surgery to ensure that none of these items is left inside the patient. Despite the numerous precautions in place, in approximately 1 in 1500 cases, something gets left behind inside the patient’s body. This paper presents ASSIST, an automated system for surgical instrument and sponge tracking that increases the safety of surgical procedures. ASSIST utilizes RFID (Radio Frequency Identification) technology to aid in accounting for all items used during surgery. The design takes into account safety, simplicity, ease of deployment, and ease of use. An initial evaluation utilizing RFID-tagged sponges demonstrates that ASSIST can reliably track surgical sponges with minimal impact to current operating room procedures. Sources of error that can impact the reliability of the system are also discussed. I