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Spatial Frequency Domain Imaging (SFDI)
SFDI, also known and modulated imaging (MI) is a non-contact optical imaging technology capable of quantitative imaging, spectroscopy, and tomography of tissues over a large field-of-view (many cm) and up to a depth of ~1cm. While compatible with time-modulation methods, SFDI alternatively uses spatially-modulated illumination for imaging of tissue constituents. Periodic illumination patterns of various spatial frequencies are projected over a large area of tissue, and the remitted diffuse light is detected via a CCD camera. The spatially-varying (2D or 3D) absorption, scattering and/or fluorescence characteristics of the sample can then be reconstructed from the measured diffuse reflectance and/or fluoresence, respectively. Estimation of intrinsic tissue chromophores is further enabled by quantifying absorption at many wavelengths. For example, images of tissue hemoglobin concentration (total, oxy- and deoxy-forms) and tissue oxygen saturation, lipid, water, and melanin concentration can all be quantified using appropriate red or infrared wavelengths. There are currently 5 SFDI instruments available for collaborative studies.

Features common to both:
  • Non-contact imaging geometry
  • Automated data acquisition
  • User-selectable spatial frequencies
  • Cart-based system for transport
Specific Features:


  • Commercial digital projector-based system
  • Variable field-of-view (5mm-10cm)
  • Visible white light illumination (450-700nm, mercury lamp)
  • Bandpass detection filters on motorized filter wheel
  • Fluorescence excitation filtering available
  • Black-box for fluorescence-mode detection
  • Currently housed in LAMMP
  • Common uses: single-wavelength studies, tomographic imaging studies


  • Custom-built NIR projector system
  • Variable field-of-view (5mm-10cm)
  • White light illumination (650-1000nm, QTH lamp)
  • Flexible acquisition geometry for lab & clinic use
  • Currently housed in LAMMP
  • Commonly used for spectroscopic imaging studies

WiFI #1 & WiFI #4 Clinical systems

(identical to each other)
  • LED based (4 wavelength LEDs; 658 nm, 730 nm, 850 nm, 970 nm) Fixed field of view (13.5 cm x 10.5 cm)
  • Can quantify oxy-hemoglobin, deoxy-hemoglobin, tissue oxygen saturation, total hemoglobin and reduced scattering coefficient.
  • Imaging times range from 0.5 to 10 seconds depending on the application.
  • Mounted on an articulating arm attached to a cart.
  • WiFI #1 housed at UCI Medical Center
  • WiFI #4 housed in LAMMP

Spatially Modulated Quantitative Spectroscopy (SMoQS)

  • Can perform quantitative spectroscopy on a single "pixel" (2mm x 2mm) of tissue.
  • Imaging Spectrometer + CCD detection spans the range from 450 - 1000 nm
  • This system can be used for either small animal or in-vivo human studies.

[Return to list of shared instrumentation]


Contact Us

  • Hanna Kim
    Resource Coordinator

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