High-speed line-field confocal holographic microscope for quantitative phase imaging

Abstract

Abstract:We present a high-speed and phase-sensitive reflectance linescanning confocal holographic microscope (LCHM). We achieved rapid confocal imaging using a fast line-scan CCD camera and quantitative phase imaging using off-axis digital holography (DH) on a 1D, line-by-line basis in our prototype experiment. Using a 20 kHz line scan rate, we achieved a frame rate of 20 Hz for 512x512 pixels en-face confocal images. We realized coherent holographic detection two different ways. We first present a LCHM using off-axis configuration. By using a microscope objective of a NA 0.65, we achieved axial and lateral resolution of ~3.5 micrometers and ~0.8 micrometers, respectively. We demonstrated surface profile measurement of a phase target at nanometer precision and the digital refocusing of a defocused confocal en-face image. Ultrahigh temporal resolution M mode is demonstrated by measuring the vibration of a PZTactuated mirror driven by a sine wave at 1 kHz. We then report our experimental work on a LCHM using an in-line configuration. In this inline LCHM, the coherent detection is enabled by moving the reference arm at a constant speed, thereby introducing a Doppler frequency shift that leads to spatial interference fringes along the scanning direction. Lastly, we present a unified formulation that treats off-axis and in-line LCHM in a unified joint spatiotemporal modulation framework and provide a connection between LCHM and the traditional off-axis DH. The presented high-speed LCHM may find applications in optical metrology and biomedical imaging.

Interferenceless coded aperture correlation holography–a new technique for recording incoherent digital holograms without two-wave interference

“…Digital holograms are important in the imaging technology because they are used as a compressed storing medium in which 3D information is stored into a 2D digital matrix. Furthermore, digital holograms can be composed together to a hologram with a large synthetic aperture [31], they can be used for imaging objects covered by a scattering medium [4] and they can be processed to yield various 2D sections of a 3D image [32], or edgeenhanced images [33].…”

High-resolution label-free imaging of tissue morphology with confocal phase microscopy

“…Optical coherence tomography has been applied to phase imaging of single cells and depth-resolved phase imaging of tissue [37,38]. Recently, synthetic optical holography (SOH) [39] was demonstrated as a holographic approach to confocal QPI [40][41][42]. Implemented in a commercial confocal instrument, SOH allowed confocal QPI based on a beam scanning approach with frame acquisition times on the order of seconds, thus mitigating the slow scanning speed of initial demonstrations of confocal QPI based on sample scanning [43,44].…”

Accessible quantitative phase imaging in confocal microscopy with sinusoidal-phase synthetic optical holography

“…By implementing SOH, the reference mirror vibration was replaced by a mirror movement at constant velocity, and imaging speed was improved by more than a magnitude [30]. Further, SOH was shown to enable quantitative phase imaging in confocal microscopy for optical surface profiling with sub-nanometer vertical sensitivity [31], confocal hologram recording [33], fast quantitative phase imaging in a line-scanning modality [34] and transient vibration imaging [35]. These holographic as well as related interferometric techniques for phase retrieval were typically implemented on custom systems that afforded the necessary space and flexibility in reconfiguring the optical setup.…”