The purpose of this project is to develop a multifocal optical coherence microscope (OCM). The proposed OCM will allow noninvasive imaging of unstained biological specimens, with millisecond temporal resolution and sub-cellular spatial resolution in three dimensions. During this project, we expect to achieve three specific aims as follows: 1) Construction of a full-field OCM: We plan to develop a digital camera based full-filed OCM. An electro- optic phase modulator will be used for rapid, vibration-free phase modulation of the reference beam. A near infrared light will be employed to ensure high penetrating depth of OCM imaging. A four-step phase shifting algorithm will be used for concurrent reconstruction of intensity-sensitive and phase-sensitive OCM images. Polarization-sensitive imaging capability will be added to achieve high contrast imaging of biological specimens with birefringence characteristics. 2) Development of a multifocal OCM: In order to ensure the stability of sampling volume, we will employ a multifocal illumination and virtual pinhole confocal imaging strategy for further improvement of the full-field OCM. The combination of the virtual pinhole confocal imaging and low coherence gating mechanism will provide a two-stage `filtering'system for effective rejection of undesired noise light: 1) Computer- synthesized virtual pinholes will be used to reject out-of-focus light;2) Low coherence gating mechanism will be used to reject cross-talk noise light between adjacent sampling volumes. Using a near infrared light (center wavelength: ~800 nm) with 100 nm bandwidth, we anticipate a depth resolution better than 3 ?m. The lateral (perpendicular to the light axis) resolution will be optical diffraction limited. 3) Functional test of the multifocal OCM: A series of biological tissues/cells will be used to assess the intensity-sensitive, phase-sensitive, and polarization-sensitive imaging capabilities of the proposed OCM. Multi-modal OCM imaging of human skin will be also implemented for preliminary test of imaging stability of the proposed instrument for in vivo application. Although the proposed OCM promises a versatile imaging platform for a variety of biomedical applications, this project will focus on proof-of-concept of the imaging system.
The proposed multifocal optical coherence microscope can provide fast, noninvasive imaging with sub-cellular spatial resolution in three dimensions. We anticipate that the multifocal OCM will find a wide range of applications in cell biology, neurobiology, tissue engineering, dermatology, and ophthalmology.
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