On-chip differential interference contrast microscopy using lensless digital holography

Abstract

We introduce the use of a birefringent crystal with lensless digital holography to create an on-chip differential interference contrast (DIC) microscope. Using an incoherent source with a large aperture, in-line holograms of micro-objects are created, which interact with a uniaxial crystal and an absorbing polarizer, encoding differential interference contrast information of the objects on the chip. Despite the fact that a unit fringe magnification and an incoherent source with a large aperture have been used, holographic digital processing of such holograms rapidly recovers the differential phase contrast image of the specimen over a large field-of-view of ~24 mm2.

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.…”

In-line hologram segmentation for volumetric samples

“…1(a)] and is applicable whenever the wave field of the objects can be considered only as a perturbation of the reference; that is, sparse, slightly scattering objects are to be recorded [16,18]. Using such an architecture, even lensless DHM systems become realizable [19,20].…”

“…Special fiber-coupled lasers provide the illumination and guarantee the even spherical reference wave field in this device [7]. In contrast to other DHM approaches, the objects spread all over a substantial volume and do not concentrate in a thin layer [11,12,20]. Therefore, their diffractions can considerably overlap not only at the hologram recording but also at the reconstruction plane.…”

Iterative Noise Reduction in Digital Holographic Microscopy

“…Some DHM setups employ microscope objectives to form the image of the object (Ferraro et al, 2003;Mann et al, 2005;. However, it is also possible to implement DHM in a lensless setup, where the light field scattered from the object is used instead of its projected image (Wagner et al, 1999;Schnars-Juptner, 2002;Repetto et al, 2004;Cruz et al, 2008;Oh et al, 2010). A conventional setup in DHM is based on the use of an external reference wave (RW), which interferes with the field generated by the object, forming an intensity pattern which is known as hologram of the field (Takeda et al, 1982;Kreis, 1986;Yamaguchi-Zhang, 1997;Yamaguchi et al, 2001;Arrizón-Sanchez, 2004;Liebling, 2004;Quian, 2006;Meneses-Fabian, 2006;Guo, 2007;Cruz et al, 2009).…”