770 research outputs found
Fast Autofocusing using Tiny Transformer Networks for Digital Holographic Microscopy
The numerical wavefront backpropagation principle of digital holography
confers unique extended focus capabilities, without mechanical displacements
along z-axis. However, the determination of the correct focusing distance is a
non-trivial and time consuming issue. A deep learning (DL) solution is proposed
to cast the autofocusing as a regression problem and tested over both
experimental and simulated holograms. Single wavelength digital holograms were
recorded by a Digital Holographic Microscope (DHM) with a 10
microscope objective from a patterned target moving in 3D over an axial range
of 92 m. Tiny DL models are proposed and compared such as a tiny Vision
Transformer (TViT), tiny VGG16 (TVGG) and a tiny Swin-Transfomer (TSwinT). The
experiments show that the predicted focusing distance is
accurately inferred with an accuracy of 1.2 m in average in comparison
with the DHM depth of field of 15 m. Numerical simulations show that all
tiny models give the with an error below 0.3 m. Such
a prospect would significantly improve the current capabilities of computer
vision position sensing in applications such as 3D microscopy for life sciences
or micro-robotics. Moreover, all models reach state of the art inference time
on CPU, less than 25 ms per inference
Versatile optimization-based speed-up method for autofocusing in digital holographic microscopy
We propose a speed-up method for the in-focus plane detection in digital holographic microscopy that can be applied to a broad class of autofocusing algorithms that involve repetitive propagation of an object wave to various axial locations to decide the in-focus position. The classical autofocusing algorithms apply a uniform search strategy, i.e., they probe multiple, uniformly distributed axial locations, which leads to heavy computational overhead. Our method substantially reduces the computational load, without sacrificing the accuracy, by skillfully selecting the next location to investigate, which results in a decreased total number of probed propagation distances. This is achieved by applying the golden selection search with parabolic interpolation, which is the gold standard for tackling single-variable optimization problems. The proposed approach is successfully applied to three diverse autofocusing cases, providing up to 136-fold speed-up
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