Compact lensless phase imager

Abstract

Lensless quantitative phase imaging is of high interest for obtaining a large field of view (FOV), typically the size of the camera chip, to observe biological cell material with high contrast. It has the potential to be widely spread due to its inherent simplicity. However, the tradeoff is the added complexity due to the illumination. Current illumination systems are several centimeters away from the sample, use mechanics to obtain super resolution (i.e., smaller than the detector pixel size) or different illumination directions, and block the view to the sample. In this paper, we propose and demonstrate a side illumination system which reduces the height by an order of magnitude while providing an unobstructed view of the sample. We achieve this by shaping the illumination using multiplexed analog holograms that produce 9 illumination angles. We demonstrate experimentally imaging of phase samples with a FOV of ~17mm 2 .

Compact in-line lensfree digital holographic microscope

“…This can be prior knowledge about the sample as support constraints [31] , [32] , [33] , [34] , [35] . The required information can also be gathered by recording several holograms of the same sample with for instance different distances between the sample and the camera [36] , [37] , different light source wavelengths [38] , or by illuminating the sample with different illumination directions [24] , [39] . The last method is used in the proposed device.…”

“…Another advantage is the field of view (FOV) which is equal to the size of the camera chip (∼several mm 2 ). Most implementations use in-line digital holography [22] , [23] , [24] . The existing setups use partially coherent light (LEDs) in order to have less noisy images by limiting speckle and to be cost effective.…”

GlobalBioIm: A Unifying Computational Framework for Solving Inverse Problems

“…These measurements can take the form of traditional images, as in the case of 3D deconvolution microscopy [1], interferograms/holograms, modulations [2], or 2D projections of a specimen as in refractive-index tomography [3].…”

“…% R e g u l a r i z e r F u n c t i o n ( H e s s i a n −S h a t t e n Norm ) 2 OpReg= LinOpHess ( s i z e ( a c q ) ) ; % R e g u l a r i z e r O p e r a t o r ( H e s s i a n −S h a t t e n Norm ) …”

Lensless imaging through multiple phase patterns illumination

“…[12][13][14] In lensless microscopy, this factor is corrected through x − y translation of the illumination source. 8 The lensless microscopic system is made more compact through the side illumination technique 15 to reduce the complexity while achieving a large field of view. The reconstruction process is simplified through the phase mask pattern that is placed before the sample, where information of a sample is encoded.…”