18 October 2004 Parasitic filtering in position detection systems for optical tweezers
Author Affiliations +
In a typical position detection system for optical tweezers, laser light impinges on a quadrant photodiode, and the signal from the four quadrants of the diode is used to determine the position of a trapped object. A widely used position detection system consists of a Si-PIN photodiode and an infrared laser. In previous work we have demonstrated with two distinct experimental methods how such a system may act as an unintended low-pass filter and we modeled its physical origin mathematically. Here we demonstrate that the general solution to this model can account precisely for the "parasitic" filter's effects up to as large frequencies as we can measure, approximately 100 kHz. Thus we increase the useful bandwidth of tweezers experiments by nearly two decades. This opens for investigations of phenomena in biophysics, soft matter, and polymer science at much higher frequencies than before.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kirstine Berg-Sorensen, Kirstine Berg-Sorensen, Erwin J. G. Peterman, Erwin J. G. Peterman, Lene Broeng Oddershede, Lene Broeng Oddershede, Meindert van Dijk, Meindert van Dijk, Ernst-Ludwig Florin, Ernst-Ludwig Florin, Christoph F. Schmidt, Christoph F. Schmidt, Henrik Flyvbjerg, Henrik Flyvbjerg, } "Parasitic filtering in position detection systems for optical tweezers", Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.559582; https://doi.org/10.1117/12.559582

Back to Top