Significance: Optical coherence tomography (OCT) has proven useful for detecting various oral maxillofacial abnormalities. To apply it to clinical applications including biopsy guidance and routine screening, a handheld imaging probe is indispensable. OCT probes reported for oral maxillofacial imaging were either based on a bulky galvanometric mirror pair (not compact or long enough) or a distal-end microelectromechanical systems (MEMS) scanner (raised safety concerns), or adapted from fiber-optic catheters (ill-suited for oral cavity geometry).
Aim: To develop a handheld probe featuring great compactness and excellent maneuverability for oral maxillofacial tissue imaging.
Approach: A dual-axis MEMS scanner was deployed at the proximal end of the probe and the scanned beam was relayed to the distal end through a 4f configuration. Such design provides both a perfect dual-axis telecentric scan and excellent compactness.
Results: A handheld probe with a rigid part 70 mm in length and 7 mm in diameter and weighing 25 g in total was demonstrated through both ex vivo and in vivo experiments, including structural visualization of various oral maxillofacial tissues and monitoring the recovery process of an oral mucosa canker sore.
Conclusions: The proposed probe exhibits excellent maneuverability and imaging performance showing great potential in clinical applications.
We propose a 650/1550nm wavelength Mux/DeMux for SS-OCT system based on silica-on-silicon (SoS), in which
mixing red/infrared lightbeams can be fully separated at low insert loss through special cascaded multimode interference
(MMI) structure. Each independent lightbeam is entered into its respective channel by selecting proper width and length
of the MMI. By using of Finite Difference Beam Propagation Method (FD-BPM), the Mux/DeMux is optimally designed
in size of 1×0.1cm2, working at 650nm and 1550nm simultaneously. The results show the degrees of separation between
two lightwaves are super high, loss of infrared light is less than 0.5dB and 1dB, and its output power stability is less than
0.25dB and 0.8dB, in 1510nm -1570nm and in 1500nm -1600nm, respectively. The Mux/DeMux can be used in SS-OCT
PIC based on SoS.
Despite advantages of distributed fiber optic sensor systems, the stability, reliability and limitation of physical parameters detected by the systems are still the bottlenecks of the applications in industrial control fields. In this paper, we compare different structures of fiber optic sensor networks based on special needs for manufacturing control and monitoring. A double-bus fiber optic sensor network directly used in industrial scene is presented. The multiplexing methods, such as time division multiplexing, frequency division multiplexing and code division multiplexing are analyzed. The result demonstrates that the double-bus fiber optic sensor network is adapted to use as manufacturing control systems in industrial environment, which offer low crosstalk levels, high signal to noise ratio and low optical path loss.
A new system of comparative pressure leak-detection with fiber-optic sensors is advanced and studied. The expression for differential pressure, detecting time, and minimum detectable leak rate is derived through the study of the pressure in the detected device applied pressure with relation to the detecting time. The fiber-optic differential pressure sensor with high sensitivity and stability is presented and designed. Minimum value of relative differential pressure detected is approximately 3X10-5. Finally, an example of the system used in industrial production is given.