Dynamic optical tomographic imager with optimized digital lock-in filtering

Joseph M. Lasker, James M. Masciotti, Li Yang, Chris Fong, Andreas H. Hielscher

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We describe a new dynamic optical tomography system that is, unlike currently available analog instrumentation, based on digital data-acquisition and filtering techniques. At the heart of this continuous wave instrument is a digital signal processor (DSP) that collects, collates, processes, and filters the digitized data set. A digital lock-in filter that has been designed for this particular application maximizes measurement fidelity. The synchronously-timed processes are controlled by a complex programmable logic device (CPLD) that is also used in conjunction with the DSP to orchestrate data flow. Real-time data rates as high as 140Hz can be achieved. The operation of the system is implemented through a graphical user interface designed with LabVIEW software, Performance analysis shows very low system noise (∼600fW RMS noise equivalent power), excellent signal precision (<0.04% - 0.2%) and long-term system stability (<1% over 40 min). A large dynamic range (∼195dB) accommodates a wide scope of measurement geometries and tissue types. First experiments on tissue phantoms show that dynamic behavior is accurately captured and spatial location can be correctly tracked using this system.

Original languageEnglish (US)
Title of host publicationDiffuse Optical Imaging of Tissue
StatePublished - 2007
EventDiffuse Optical Imaging of Tissue - Munich, Germany
Duration: Jun 19 2007Jun 21 2007

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


ConferenceDiffuse Optical Imaging of Tissue


  • Digital lock-in detection
  • Dynamic imaging
  • Instrumentation
  • Optical tomography

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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