Laser Microbeam and Medical Program    »     People  |   Education & Dissemination  |   Research & Resources  |   Publications
Laser Speckle Imaging (LSI)

LSI is a non-contact optical imaging technology capable of quantitative mapping of blood flow. Coherent light is used to irradiate the object of interest. A CCD or CMOS camera is used to image the irradiated object, and a speckle pattern is observed. Local fluctuations in speckle pattern occur due to motion of optical scatterers, such as red blood cells. If the image exposure time is greater than a characteristic fluctuation time of the scatterers, then local blurring of the speckle pattern occurs. Using various algorithms, a local speckle contrast value (K) is calculated at each pixel. K is high when the degree of local blurring is low (i.e., stationary scatterers), and K is low when the degree of local blurring is high (i.e., moving scatterers). With an assumption made on the motion characteristics (e.g., Brownian, ordered) of the moving scatterers, estimates of the speckle decorrelation time Tc are made from the K value. The relative degree of scatterer motion, which we call Speckle Flow Index (SFI), is assumed to be the reciprocal of Tc.

There are currently six LSI instruments available for collaborative studies.

Features common to the instruments:
  • Non-contact imaging geometry
  • Variable field of view (0.35mm-20mm)
Specific Features:

LSI1

  • Designed for window chamber imaging
  • Color CCD camera (Point Grey Flea)
  • Macro lens
  • Typical field of view = ~10 mm
  • 30mW, 633-nm HeNe laser
  • Transillumination geometry
  • Broadband halogen lamp
  • Heating pad and gas anesthesia for small animal imaging

LSI2

  • Designed for clinical imaging
  • Monochrome, thermoelectrically-cooled, 12-bit camera (QImaging Retiga 2000R)
  • Typical field of view = 20 cm x 20 cm
  • 30mW, 633-nm HeNe laser
  • Epiillumination geometry
  • Purpose-designed LabVIEW software
  • Real-time blood-flow imaging capabilities enabled with NVIDIA GPU processing
  • Cart-based system

LSI3

  • Designed for window chamber imaging
  • Monochrome CCD camera equipped with electro-optic tunable filter (420-720nm) (Nuance, Caliper Life Systems)
  • Macro lens
  • Typical field of view = ~10 mm
  • 30mW, 633-nm HeNe laser
  • Transillumination geometry
  • Broadband halogen lamp
  • Water-based heating pad and gas anesthesia for small animal imaging
  • Hemoglobin oxygen saturation imaging capabilities enabled

LSI7

  • Monochrome CCD camera (Pt. Grey Firefly)
  • Macro lens
  • Typical field of view = ~20 mm
  • 50mW, 785-nm long-coherence laser
  • Epiillumination geometry
  • Broadband halogen lamp

LSI8

  • Designed for LSI microscopy
  • Designed around a Nikon inverted fluorescence microscope
  • Color CCD camera (Pt. Grey Grasshopper2)
  • Equipped with 1x-40x objectives
  • Typical field of view used for LSI= 3.5mm
  • 30mW, 633-nm long-coherence laser
  • Epiillumination geometry
  • Broadband mercury lamp
  • Equipped with filters for DAPI, FITC, and TRITC fluorescence imaging

cSFDI

  • First-generation coherent structured illumination system
  • Monochrome CCD camera (QImaging Retiga EXi)
  • Typical field of view used = 10mm
  • Epiillumination geometry
  • Liquid Crystal on Silicon (LCoS) spatial light modulator

[Return to list of shared instrumentation]

Research

Contact Us

  • Hanna Kim
    Resource Coordinator
    Phone:949.824.2251
    Email: hhkim3@uci.edu

Supported by


P41EB015890