Phase-sensitive Optical Imaging and Turbidity Suppression

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The aim of this core research area is to exploit wave nature of light for developing next-generation optical tools for biomedical applications. The use of optical phase in biological imaging of cells has a rich and long history dating back to Zernike’s invention of phase-contrast microscopy [1], for which he won the 1953 Nobel Prize. Later, differential interference contrast microscopy provided further sensitivity, outstanding contrast, high spatial resolution, and optical sectioning capability. Recent technical advances in phase microscopy have focused on obtaining quantitative information through the use of interferometry and digital imaging devices such as CCD cameras [2-6].

The LBRC has been active in the field of quantitative phase microscopy for over a decade, and has been responsible for several major technological advances in this field over the past. Specific examples for wide-field configurations include Fourier phase microscopy [7], Hilbert phase microscopy [8], and diffraction phase microscopy (DPM) [9]. DPM is particularly interesting as it minimizes system phase noise by using a near common-path configuration, and permits single-shot wide-field measurement via off-axis holography. This achieved by placing a transmission grating in a conjugate plane. A pinhole is used in the Fourier plane of a 4f system (following the grating) to filter spatial frequency information of the sample in one of the beams after grating, providing a plane reference wave in the imaging plane. In this configuration, the sample and reference beams share most of the beam path, which ensures that the system phase noise is minimized. The single-shot interferogram can be post-processed to determine the sample amplitude as well as phase information. LBRC has also made remarkable progress in tomographic phase microscopy (TPM), which readily provides 3-D refractive index maps of live cells containing vital structural and functional information [10].

Ongoing projects

  1. Self-reference quantitative phase microscope [ PDF ]
  2. High-resolution tomographic phase microscope [ PDF ]
  3. Wide-field digital optical phase conjugation [ PDF ]
  4. Scattering matrix measurements and applications [ PDF ]
  5. Wide-field reflection phase microscope
  6. High-speed dispersion phase microscope
  7. 3-D holographic flow cytometer

Background Publications

  1. F. Zernike, “How I discovered phase contrast,” Science, vol. 121, pp. 345-9, Mar 11 1955.
  2. G. A. Dunn and D. Zicha, “Dynamics of fibroblast spreading,” Journal of Cell Science, vol. 108, p. 1239, 1995.
  3. T. E. Gureyev, A. Roberts, and K. A. Nugent, “Partially coherent fields, the transport-of-intensity equation, and phase uniqueness,” Journal of the Optical Society of America A, vol. 12, pp. 1942-1946, 1995.
  4. J. W. Goodman and R. W. Lawrence, “Digital image formation from electronically detected holograms,” Applied physics letters, vol. 11, p. 77, 1967.
  5. I. Yamaguchi and T. Zhang, “Phase-shifting digital holography,” Optics letters, vol. 22, pp. 1268-1270, 1997.
  6. E. Cuche, F. Bevilacqua, and C. Depeursinge, “Digital holography for quantitative phase-contrast imaging,” Optics Letters, vol. 24, pp. 291-293, 1999.
  7. N. Lue, W. Choi, G. Popescu, T. Ikeda, R. R. Dasari, K. Badizadegan, et al., “Quantitative phase imaging of live cells using fast Fourier phase microscopy,” Applied optics, vol. 46, pp. 1836-1842, 2007.
  8. T. Ikeda, G. Popescu, R. R. Dasari, and M. S. Feld, “Hilbert phase microscopy for investigating fast dynamics in transparent systems,” Opt. Lett, vol. 30, pp. 1165-1167, 2005.
  9. G. Popescu, T. Ikeda, R. R. Dasari, and M. S. Feld, “Diffraction phase microscopy for quantifying cell structure and dynamics,” Optics letters, vol. 31, pp. 775-777, 2006.
  10. W. Choi, C. Fang-Yen, K. Badizadegan, S. Oh, N. Lue, R. R. Dasari, et al., “Tomographic phase microscopy,” Nature Methods, vol. 4, pp. 717-719, 2007.