Fourier-transform holographic microscope

Abstract

We describe a holographic microscope with a spatial resolution approaching the diffraction limit. The instrument uses a tiny drop of glycerol as a lens to create the spherically diverging reference illumination necessary for Fourier-transform holography. Measurement of the point-spread function, which is obtained by imaging a knife edge in dark-field illumination, indicates a transverse resolution of 1.4 microm with wavelength lambda = 514.5 nm. Longitudinal resolution is obtained from the holograms by the numerical equivalent of optical sectioning. We describe the method of reconstruction and demonstrate the microscope's capability with selected biological specimens. The instrument offers two unique capabilities: (1) it can collect three-dimensional information in a single pulse of light, avoiding specimen damage and bleaching; and (2) it can record three-dimensional motion pictures from a series of light pulses. The conceptual design is applicable to a broad range of wavelengths and we discuss extension to the x-ray regime.

Lensfree on-chip imaging using nanostructured surfaces

“…[1][2][3][4]6,7 Recent results confirmed the promising potential of lensfree in-line holography especially for high-throughput cytometry applications. 6 Quite recently, lensfree on-chip imaging has also been extended to fluorescence microscopy to achieve an ultrawide imaging field-of-view ͑FOV͒ of Ͼ8 cm 2 without the use of any lenses or mechanical scanning.…”

“…[1][2][3][4][5][6][7][8] Such on-chip microscope designs would especially benefit microfluidic systems to create powerful capabilities especially for medical diagnostics and cytometry applications. Being light-weight and compact, lensfree imaging can also potentially create an important alternative to conventional lens-based microscopy especially for telemedicine applications.…”

Digital holographic microscopy applied to measurement of a flow in a T-shaped micromixer

“…In digital holographic microscopy, two different approaches can be distinguished: the so-called Fourier transform approach was introduced by Haddad et al (1992) and the convolution approach was described by Sheng et al (2006). This paper follows the second approach, which is mainly motivated by the fact that-in contrast to the first approach-the pixel size in the reconstruction planes does not depend on the longitudinal position of the reconstruction plane which is convenient-if not essential-for a correct analysis of volumetric fluid motion.…”

“…An instrument that combines microscopy and digital holography is generally referred to as a Digital Holographic Microscope (DHM). Although a significant amount of work has been published on the application of a DHM in biological research (Haddad et al 1992;Dubois et al 1999;Xu et al 2003) and in micro-structure research (Xu et al 2001), only a few publications have appeared on the application of a DHM to microfluidics. Satake et al (2005) first described the application of a DHM to flow measurements in a micro channel and later presented improved results (Satake et al 2006).…”

Iterative Noise Reduction in Digital Holographic Microscopy

“…Digital holographic microscopy (DHM) is an optical technique useful to retrieve quantitative information of microscopic objects with subwavelength axial accuracy (Haddad et al, 1992;Zhang-Yamaguchi, 1998;Pedrini et al, 1999;Ferraro et al, 2005). An important feature of DHM is its non-invasive character that allows the appropriate study of microorganisms in vivo (Car et al, 2004;Marquet et al, 2005;Rappaz et al, 2005Javidi et al, 2006;Charrière et al, 2006).…”