Stories with Tag Imaging

• Nonlinear soundsheet microscopy:imaging opaque organs capillary/cellular scale

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  Posted: 2025-04-05 15:13:00

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  Researchers have developed a nonlinear soundsheet microscopy technique capable of imaging opaque organs at capillary and cellular resolution. This method uses focused ultrasound pulses to generate microbubbles within the tissue, which serve as transient acoustic sources. Detecting the nonlinear acoustic emissions from these microbubbles allows for high-resolution, three-dimensional imaging through scattering media like biological tissue. This approach overcomes limitations of optical microscopy in opaque tissues and provides a promising new tool for studying microvasculature and cellular structures in vivo.

  A groundbreaking advancement in biomedical imaging, detailed in the Science publication "Nonlinear soundsheet microscopy: Imaging opaque organs at capillary/cellular scale," introduces a novel technique capable of visualizing the intricate microstructures within optically opaque organs, down to the level of individual capillaries and cells. This technique, termed nonlinear soundsheet microscopy, circumvents the limitations of traditional optical microscopy, which struggles to penetrate deep into dense tissues due to scattering and absorption of light. Instead of relying on photons, this method leverages the unique properties of ultrasound combined with nonlinear optical phenomena.

  The process involves illuminating the tissue sample with a thin, two-dimensional sheet of ultrasound waves, aptly named a "soundsheet." This soundsheet acts as a virtual "acoustic lens" within the tissue. Simultaneously, a pulsed laser is focused onto this soundsheet plane. The interaction between the ultrasound and the focused laser light generates nonlinear optical signals, such as two-photon fluorescence and third-harmonic generation, specifically from the region where the laser and soundsheet intersect. These nonlinear signals are then detected and used to construct high-resolution images.

  Crucially, the ultrasound soundsheet modulates the optical properties of the tissue within the focal plane, effectively tagging the generated photons. This allows for highly sensitive detection of the nonlinear optical signals against a significantly reduced background of scattered light originating from outside the soundsheet plane. This dramatic reduction in background noise is key to enabling deep tissue imaging.

  Furthermore, the soundsheet method allows for rapid scanning of the tissue by electronically steering the ultrasound beam, enabling the acquisition of three-dimensional images at impressive frame rates. This capability opens up exciting possibilities for real-time in vivo imaging of dynamic processes at the cellular and capillary level.

  The authors demonstrate the power and versatility of nonlinear soundsheet microscopy by imaging various opaque organs, including mouse brain, kidney, and liver, achieving resolutions sufficient to visualize individual blood cells flowing through capillaries and even subcellular structures. This technology holds immense promise for advancing our understanding of biological processes within complex tissues and could revolutionize disease diagnosis and treatment by providing unprecedented insights into the cellular and microvascular dynamics of healthy and diseased organs. It could potentially offer a powerful new tool for observing drug delivery, immune responses, and other intricate biological interactions deep within living tissues.

  • microscopy
  • nonlinear acoustics
  • soundsheet
  • Imaging
  • opaque organs
  • capillary
  • cellular scale
  • biomedical imaging
  • acoustic microscopy
  • high-resolution imaging
  • deep tissue imaging
  • organ imaging

  Summary of Comments ( 0 )
  https://news.ycombinator.com/item?id=43594090

  Verbose tl;dr

  HN commenters discuss the potential impact of the nonlinear soundsheet microscopy technique. Some express excitement about its ability to image opaque organs at capillary and cellular levels without requiring contrast agents, potentially revolutionizing medical imaging and diagnostics. Others raise questions about the scalability and practical applications of the technique, wondering about the cost, complexity, and limitations of the current implementation. Concerns about the limited penetration depth and potential for artifacts are also mentioned. Several commenters highlight the novelty of using sound for high-resolution imaging, comparing and contrasting it with existing optical microscopy techniques. A few users also point to the intriguing possibility of using this technique for non-destructive material inspection beyond medical applications. There's a general sense of cautious optimism, acknowledging the early stage of the technology but recognizing its potential transformative impact.

  The Hacker News post titled "Nonlinear soundsheet microscopy: imaging opaque organs capillary/cellular scale" linking to a Science article has generated a modest discussion with a few interesting points raised.

  One commenter questions the novelty of the technique, pointing out that photoacoustic microscopy has existed for a while and asking how this new method compares in terms of resolution, penetration depth, and speed. They specifically wonder about the practicality of the setup described in the article. This comment highlights a desire to understand the advancements this research offers over existing technologies.

  Another commenter expresses excitement about the potential of this technology for non-invasive medical imaging, especially in diagnosing diseases earlier and more accurately. They envision a future where this kind of microscopy could replace biopsies, reducing the need for invasive procedures. This optimistic perspective emphasizes the potential real-world impact of the research.

  A third comment briefly touches on the challenges associated with scaling such technologies, suggesting that cost and complexity could be significant hurdles to widespread adoption. This pragmatic observation brings a dose of realism to the discussion, acknowledging that technological advancements don't always translate to immediate practical applications.

  The remaining comments are less substantial, with some simply expressing interest in the technology and others offering minor observations. One commenter mentions the potential for combining this technique with AI for image analysis. Another notes the impressive resolution achieved.

  While the discussion is not extensive, it captures a range of perspectives on the research, from excitement about the potential benefits to pragmatic concerns about practical implementation. The most compelling comments center on the comparison to existing technologies, the potential impact on medical diagnosis, and the challenges of scaling the technology.

• Optical Fresnel zone plate flat lens: colored photoresist through I-line stepper

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  Posted: 2025-01-17 13:40:33

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  Researchers have fabricated a flat, diffraction-based lens using a single layer of colored photoresist patterned via conventional I-line stepper lithography. By varying the photoresist's absorbance at different wavelengths, they created a Fresnel zone plate structure that focuses different colors of light at different focal lengths. This chromatic aberration is typically a drawback, but here it's exploited to produce color filtering and full-color imaging onto a single image sensor, eliminating the need for complex and bulky Bayer filters. This low-cost, readily-scalable fabrication method opens new possibilities for compact, multispectral imaging systems.

  This Nature Light: Science & Applications article details the fabrication and characterization of a novel flat lens based on the Fresnel zone plate principle, achieved using a conventional I-line stepper lithography process and a colored photoresist. Traditional Fresnel zone plates, while offering potential advantages in terms of compactness and cost-effectiveness compared to conventional refractive lenses, suffer from chromatic aberration due to their diffractive nature. Different wavelengths of light focus at different distances, resulting in blurry images and limiting their applicability, especially for full-color imaging. This research overcomes this limitation by leveraging the wavelength-dependent absorption properties of a commercially available colored photoresist.

  The researchers meticulously designed a multi-level Fresnel zone plate structure. By carefully tuning the exposure dose during the lithography process, they controlled the depth of the etched features within the colored photoresist. Crucially, the colored photoresist exhibits varying degrees of absorption for different wavelengths of light (specifically, the I-line wavelength used for lithography and the target wavelengths for imaging - blue, green, and red). This differential absorption enables the creation of distinct zone profiles for each color channel within a single lens element. The fabrication process involves multiple exposures at optimized doses, effectively creating a superimposed set of Fresnel zone plates tailored for different wavelengths within the same photoresist layer.

  The resulting lens demonstrates a remarkable ability to focus blue, green, and red light at the same focal plane, effectively mitigating chromatic aberration. The authors rigorously characterize the lens performance through experimental measurements and simulations, showcasing the achieved focusing efficiency and the reduction in chromatic focal shift. They demonstrate a significant improvement in the polychromatic focusing efficiency compared to conventional single-material Fresnel zone plates. The use of a standard I-line stepper for fabrication underscores the potential for cost-effective mass production of these chromatic-aberration-corrected flat lenses. This approach offers a promising pathway towards integrating compact and high-performance optical elements into a wide range of applications, including imaging, sensing, and virtual/augmented reality devices, without resorting to complex and expensive fabrication techniques. The researchers suggest that further optimization of the photoresist formulation and the lithography process could lead to even better performance and broader applicability of this innovative flat lens technology.

  • optics
  • Fresnel Zone Plate
  • Flat Lens
  • Photolithography
  • I-Line Stepper
  • Colored Photoresist
  • Nanofabrication
  • Microoptics
  • Diffractive Optics
  • Imaging
  • Lens Design
  • Optical Materials
  • photonics

  Summary of Comments ( 5 )
  https://news.ycombinator.com/item?id=42737401

  Verbose tl;dr

  HN commenters discuss the practicality and implications of the Fresnel zone plate lens fabrication method described in the linked Nature article. Some express skepticism about its real-world applicability due to chromatic aberration and limited resolution, pointing out that current multi-element lens systems already address these issues effectively, particularly for photography. Others find the technique interesting for specialized applications like microscopy or lithography where simplicity and cost-effectiveness might outweigh the drawbacks. The potential for customizing the focal length and numerical aperture for specific wavelengths is also highlighted as a potential advantage. A few commenters delve into the technical details of the fabrication process, questioning aspects like alignment precision and the impact of resist thickness variations. Overall, the consensus seems to be that while the approach isn't revolutionary for general-purpose optics, it offers intriguing possibilities for niche applications.

  The Hacker News post titled "Optical Fresnel zone plate flat lens: colored photoresist through I-line stepper," linking to a Nature article about creating flat lenses using colored photoresist, has a modest number of comments, generating a brief but focused discussion.

  Several commenters focus on the practical implications and limitations of this technology. One commenter questions the scalability of the fabrication process, specifically regarding the use of an I-line stepper, which they believe might limit the achievable resolution and therefore the potential applications. Another user responds by agreeing with the limitations of I-line steppers but suggesting that more modern and higher resolution photolithography techniques could be employed to overcome this hurdle. This exchange highlights the manufacturing challenges in moving this technology from lab demonstration to widespread adoption.

  Another commenter points out the chromatic aberration inherent in Fresnel lenses, implying that while the research is interesting, this fundamental optical limitation would need to be addressed for broader applicability. They question the practical advantage over existing lens technologies if color correction remains a problem.

  One commenter draws a parallel between this research and previous work on diffractive optics, suggesting that the novel aspect here lies primarily in the use of colored photoresist. They question whether this approach offers significant advantages over other methods for creating diffractive elements.

  Finally, one commenter makes a more general observation about the nature of academic research, suggesting that the title of the paper might oversell the practical significance of the findings. They argue that the research primarily demonstrates a fabrication technique rather than a revolutionary new type of lens.

  In summary, the comments on Hacker News reflect a cautious but interested response to the research. They acknowledge the novelty of the fabrication technique but also raise important questions about scalability, chromatic aberration, and overall practicality compared to existing lens technologies. The discussion is grounded in a realistic understanding of the challenges involved in translating academic research into commercially viable products.