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Our products incorporate cutting-edge technologies, a result of ongoing research conducted by our team in the domains of computational optics and machine learning. This research underscores the scientific foundation of our technologies, positioning them at the forefront of their respective fields. Explore this section for an overview of our latest publications.

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Hologram Noise Model for Data Augmentation and Deep Learning (2024)

This paper introduces a noise augmentation technique designed to enhance the robustness of state-of-the-art (SOTA) deep learning models against degraded image quality, a common challenge in long-term recording systems. Our method, demonstrated through the classification of digital holographic images, utilizes a novel approach to synthesize and apply random colored noise, addressing the typically encountered correlated noise patterns in such images. Empirical results show that our technique not only maintains classification accuracy in high-quality images but also significantly improves it when given noisy inputs without increasing the training time. This advancement demonstrates the potential of our approach for augmenting data for deep learning models to perform effectively in production under varied and suboptimal conditions. 

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Classification of Holograms with 3D-CNN (2022)

A hologram, measured by using appropriate coherent illumination, records all substantial volumetric information of the measured sample. It is encoded in its interference patterns and, from these, the image of the sample objects can be reconstructed in different depths by using standard techniques of digital holography. We claim that a 2D convolutional network (CNN) cannot be efficient in decoding this volumetric information spread across the whole image as it inherently operates on local spatial features. Therefore, we propose a method, where we extract the volumetric information of the hologram by mapping it to a volume—using a standard wavefield propagation algorithm—and then feed it to a 3D-CNN-based architecture. We apply this method to a challenging real-life classification problem and compare its performance with an equivalent 2D-CNN counterpart. Furthermore, we inspect the robustness of the methods to slightly defocused inputs and find that the 3D method is inherently more robust in such cases. Additionally, we introduce a hologram-specific augmentation technique, called hologram defocus augmentation, that improves the performance of both methods for slightly defocused inputs. The proposed 3D-model outperforms the standard 2D method in classification accuracy both for in-focus and defocused input samples. Our results confirm and support our fundamental hypothesis that a 2D-CNN-based architecture is limited in the extraction of volumetric information globally encoded in the reconstructed hologram image.

Further Publications

Fast High Resolution In-line Phase Retrieval of Sparse Off-Axis Holograms (2022)
Deep-learning-based bright-field image generation from a single hologram using an unpaired dataset (2021)
High speed phase retrieval of in-line holograms by the assistance of corresponding off-axis holograms (2015)
Special multicolor illumination and numerical tilt correction in volumetric digital holographic microscopy (2014)
Multicolor digital holographic microscope (DHM) for biological purposes (2010)
In-line color digital holographic microscope for water quality measurements (2010)

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