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

Area of Science:

• Optical microscopy
• Holography
• Confocal imaging

Background:

• Confocal microscopy offers high resolution but can be slow.
• Digital holography provides quantitative phase information.
• Integrating these techniques presents challenges in speed and data acquisition.

Purpose of the Study:

• To develop a high-speed, phase-sensitive reflectance line-scanning confocal holographic microscope (LCHM).
• To achieve rapid confocal imaging and quantitative phase imaging simultaneously.
• To explore both off-axis and in-line configurations for coherent holographic detection.

Main Methods:

• Utilized a fast line-scan CCD camera for rapid confocal imaging.
• Employed off-axis digital holography (DH) for line-by-line quantitative phase imaging.
• Implemented two LCHM configurations: off-axis and in-line with Doppler shift detection.

Main Results:

• Achieved a frame rate of 20 Hz for 512x512 en-face confocal images using a 20 kHz line scan rate.
• Attained axial and lateral resolutions of ~3.5 µm and ~0.8 µm, respectively, with NA 0.65.
• Demonstrated nanometer precision surface profiling, digital refocusing, and 1 kHz vibration measurement.

Conclusions:

• The developed LCHM provides high-speed, phase-sensitive imaging capabilities.
• Both off-axis and in-line configurations are viable for LCHM implementation.
• This technology holds potential for advanced optical metrology and biomedical imaging.