Examples

Through our digital lensless holographic microscope, we were able to conduct basic static biosample inspection on honeybee foreleg and zea seeds. The first row of images represent the initially taken "holograms", with a wide field of view of 36mm² - few dozens times larger than conventional microscopes - and a resolution of 2.4μm per pixel. We were later able to enhance the resolution to 1.2μm per pixel through resolution interpolation. Part of the field of view was selected for 3D reconstruction, and the ultimate phase information is retrieved through a series of algorithms shown in the second row. The phase information is converted into 3D profiel in the third row. 

Looking at the images provided by the lensless microscope, the 3-D shape of the cellular
types are easily visible, though there are some fluctuations due to rough surfaces and other
noise sources. There are less distinctive 3-D shape then as expected because a non-living,
compressed sample was used for this study. Moreover, due to the inherent properties of the
lensless holographic microscope, some internal structures within semi-transparent samples are
also recorded. 

Through our digital lensless holographic microscope, we were able to conduct basic static industrial inspection on micro-lens. The first column of images represent the initially taken holograms through the optical setup, where the lower image is the raw hologram and the upper image is the normalized hologram. The second and third image on the first row represents the first retrieved phase information. As can be seen, it is limited in a region and requires unwrapping procedures. After unwrapping, the images are shown on the lower right corner of the figure, with both colored phase maps and 3D constructed representations. 

Holographic microscopes provide a significant advantage in the realm of industrial hardware inspection and analysis. Their ability to deliver high-resolution 3D images allows for meticulous examination, enabling the detection of even minor defects and imperfections that might escape notice with conventional 2D microscopy. Moreover, they excel in non-destructive testing, preserving the integrity of valuable or irreplaceable components. The quantitative data they generate regarding size, shape, and morphology proves invaluable for quality assessment and adherence to design specifications. Real-time monitoring capabilities are an asset for monitoring manufacturing processes, and their integration with digital technologies facilitates remote inspections in distributed or hazardous environments. This technology streamlines inspection processes, leading to cost savings and faster decision-making. Holographic microscopy's adaptability for multi-scale imaging, 3D reconstruction, material analysis, and research and development efforts underscores its vital role in enhancing product quality and competitiveness across various industrial sectors. 

Brownian motion is the random and chaotic movement of microscopic particles suspended in a fluid (liquid or gas) due to the constant bombardment by the fast-moving molecules of the surrounding medium. This phenomenon, named after the scientist Robert Brown who first observed it in 1827, is a result of thermal fluctuations and is a fundamental concept in the study of particle physics and the behavior of small particles in fluids. Brownian motion has important applications in fields such as physics, chemistry, and biology, and it provides evidence for the existence of atoms and molecules, as explained by Albert Einstein in 1905. 

Using the ability of our digital lensless holographic microscope to track 3D information of particles in semi-transparent samples, we were able to track the specific trajectory of a particle undergoing brownian motion in an observed water droplet. As seen in the figure, the particle is traced over short time frames through various holograms, leaving footprints of its path in 3D space. 

The capacity of digital lensless holographic microscopes to monitor the 3D motion of particles finds valuable application in the medical field. This technology allows researchers to gain insights into the behavior of cells, microorganisms, and biomarkers, aiding cellular biology, microbiology, and drug development. It also enhances diagnostics by enabling the early detection of diseases through the observation of disease-related particles or cells in bodily fluids. Moreover, it improves the accuracy and capabilities of flow cytometry, facilitating the identification and sorting of cells based on their characteristics. Additionally, in infectious disease research, it aids in understanding pathogen behavior, virulence, and treatment responses. Lastly, in cancer research, it supports the study of cell motility and migration, offering insights for better cancer therapies and prevention strategies. Overall, 3D motion tracking with lensless holographic microscopes contributes significantly to medical science, diagnosis, and treatment advancements.