Simple and robust digital holography for phase imaging of microstructure

Abstract

Digital holography is particularly well suited for characterization of microstructure such as surface shape, surface nanostructures and surface roughness. The wavefront recording and reconstruction with lensless Fourier transform digital holography is analyzed. By using a special 3-D minute object, the simulation and experimental investigation is performed. The accurate intensity and phase image is obtained with the lateral resolution of 2.76 ȝm. The results show that digital holography is an effective method for simultaneous amplitude-and phase-contrast imaging.

Terahertz digital holography using angular spectrum and dual wavelength reconstruction methods

“…Compelling advantages of digital holography over conventional holography include the ability to perform Fourier transforms and spectral filtering without the need for additional optical components and the simplicity by which reconstruction data may be interpreted quantitatively. Optical digital holography applications are manifold and include biological microscopy [2][3][4][5][6][7], metrology of microstructures [8][9][10], and deformation and vibration analysis [11][12][13]. Previously identified advantages of optical wavelength off-axis digital holography over in-line holography include the separation of amplitude and phase information [14], noise reduction [15], and object focusing [16], as well as the ability to quantify optical thickness and refractive index variations of an object with sub-wavelength accuracy [17].…”

“…The THz region (~0. [3][4][5][6][7][8][9][10], which lies between the microwave and infrared (IR) regions, manifests advantages of both: the former penetrates many materials such as polymers and composites but provides poor spatial resolution, while the latter provides high resolution but is mostly restricted to image surfaces. Terahertz imaging provides a unique opportunity to take IR-like highresolution imagery using RADAR-like techniques, including imagery of objects visually obscured by most dielectric materials.…”