Automatic method for focusing biological specimens in digital lensless holographic microscopy

Abstract

A self-focusing method applicable to digital lensless holographic microscopy is presented. The method searches for the global minimum of the area enclosing a given amount of energy in a region surrounding the object of interest. The proposed modified enclosed energy method has been tested on self-focusing experimental holograms of a paramecium specimen and a section of the head of a drosophila melanogaster fly. The presented self-focusing technique also has been contrasted with some of the already reported methods to seek the best focus image.

3D Holographic Observatory for Long-term Monitoring of Complex Behaviors in Drosophila

“…The image is reconstructed by convolving with the wave diffraction kernel implemented efficiently using the Fourier transform property of convolutions. Various metrics such as gradients, Laplacian, variances in intensity22, enclosed intensity energy23, or intensity profiles24 of the reconstructed image stack have been successfully applied to identify the location of sharpest focus. However, they all require the storage of the complete stack for each detected object, which quickly grows to overwhelm the memory available.…”

“…The general distribution shows that the flies are stationary over long durations of the processing time. The variation in climbing strength with aging, which can be inferred from the 3D trajectories, over long time scales have also been shown to be an effective marker for neurodegeneration23.…”

Technical and Methodical Notes on the Lensless Holographic Microscopy Applications for Helminthology and Zooparasitology. Case I: Spectrozonal/Multispectral Analysis of Ascaris Lumbricoides based on Coherent and Incoherent Light Sensor Platforms

“…Нужно отметить, что технологически удавалось достичь объёмной/ псевдообъёмной репрезентации гельминтологических и паразитологических объектов за счет использования голографии на чипе и лазерных многоугловых технологий проецирования. В силу контактной локализации и возможностей программного обеспечения впоследствии была устранена дефокусировка и потребность в Y-позиционировании с помощью ручки тонкой настройки (Trujillo, Garcia-Sucerquia, 2014). Рекордные времена экспонирования были достигнуты на терагерцовой или фемтосекундной лазерной технике (Mendoza-Yero et al, 2013), но, в целом, измерения такого типа и регистрация псевдотрёхмерных голографических паттернов и паттернов паразитов в лазерных шлирен-методах и спекл-опосредованных методах проецирования не требует этой экзотики и может быть реализована на лазерах из обычных лазерных указок.…”

Fast reconstruction of multiple off-axis holograms based on a combination of complex encoding and digital spatial multiplexing

“…Digital holography (DH) has drawn much attention in recent years due to its unique capability for digitally retrieving the complex amplitude distribution transmitted or scattered by a sample. Its applications have been extended to many areas, such as contour measurement [1][2][3][4][5] , digital microscopy [6][7][8][9] , image recognition [10][11][12] , x ray imaging [13][14][15] , electron microscopy [16][17][18] , and various noninvasive measurements [19][20][21] . According to the relative orientations between the object beam and the reference beam in a holographic recording system, DHs are often divided into two categories: on-axis and off-axis.…”