Flying particle sensors
The so-called flying particle sensor can achieve a high spatial resolution that is limited by the diameter of the trapped particle and the particle localization accuracy and precision (Zeltner, Bykov, Xie, Euser, and Russell, 2016). Therefore, we integrated a precise localization system based on optical frequency domain reflectometry (OFDR) into the particle trapping setup.
The concept of coherent OFDR is inspired by the frequency-modulated continuous-wave radar. Basically, a laser source is linearly frequency-tuned. The light which is reflected at the particle interferes with a reference beam resulting in a beat frequency that is proportional to the particle distance. In joint experiments with the Max Planck Institute for the Science of Light (MPL) a localization precision of approximately 10 µm has been achieved for a polystyrene particle trapped in the HC-PCF (Podschus, 2020). Furthermore, the application of such this sensor concept was successfully demonstrated to measure temperature (Köppel, 2021: >> read more).