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1300 Papers Presented at BiOS

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Biomedical optics took center stage at Photonics West this weekend as the BiOS 2008 conference began. Researchers from around the globe gathered in San Jose to attend a program this week that includes the presentation of 1300 papers documenting the latest clinical and technical advances in the fast-growing field.

Saturday, Jan. 19, included a presentation on a technique by Giuliano Scarcelli and Seok-Hyun Yun of Harvard Medical School that uses a Brillouin confocal microscope as a noninvasive way to monitor the density of a material as its properties change. Brillouin scattering is a process where photons are scattered in a material by acoustic vibrations (sound waves, or phonons). Scarcelli and Yun have used the technique with biological samples, such as monitoring the changes in a mouse eye lens in situ to see age-related density changes.BiOS2008Exhibition.jpg
Luminetx Director of Clinical Operations David Pennington demonstrates the VeinViewer, a tool that enables technicians to find veins for easier IV insertion, during the BiOS 2008 exhibition. Luminetx Corp. is based in Memphis, Tenn. (Photo courtesy SPIE)
A paper on the latest applications for two-focus fluorescence correlation spectroscopy detailed work by Thomas Dertinger of the University of California, Los Angeles, et al. Dertinger and his fellow researchers wanted to measure the diffusion coefficient of molecules (in this case in an isotropic liquid) and its dependence on the state of the molecules. Standard fluorescence microscopy techniques suffer from potential errors introduced by aberrations of the optical system, and size and shape of the optical focal spot, which is critical in measuring the diffusion, depends on the index of the material which varies with temperature.

Dertinger's team used a laser confocal microscope arrangement with a dual laser source of orthogonal polarization, combined the source beams with a polarization beamsplitter and separated them with a polarization wedge at the sample. The two spots were then separate by a known amount (in this case approximately 400 nm) that provided a known size calibration of the sample area. In addition they implemented both auto- and cross-correlation algorithms to accurately extract the diffusion coefficient from the measured data.

The application of adaptive optics (AO) to optical coherence tomography (OCT) for in vivo imaging of healthy and diseased retinas was the subject of a paper by Robert J. Zawadzki of the University of California/Davis Medical Center, et al. Using adaptive optics with optical coherence tomography is improving the resolution of the instrument to see 3-µm structures in the retina. A dual AO system is employed in the sample arm of the OCT instrument; one AO mirror system addresses low order aberrations while the second corrects for the higher order aberrations of the optical train (including the lens of the eye). The description of the AO system will be covered in a talk during the MEMS conference on adaptive optics.

Research by Wonshik Choi and Michael S. Feld of the Massachusetts Institute of Technology was presented in a paper on tomographic phase microscopy. Biological cell material is very hard to see because the index of refraction of the material is all very similar and close to that of water. Using phase contrast enhances the optical phase difference as light travels through the material, but the phase contrast microscope doesn't give quantitative results, it only improves the image.

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Choi and Feld sought to build a quantitative phase microscope that could produce a real-time, 3-D map of the index of the material in a living cell with enough resolution to differentiate the different materials in the cell. Doing it in real time allows researchers to see changes in the cell under varying conditions. They applied techniques used for x-ray computed tomography -- where the imaging system is rotated around the patient -- in the optical regime by analyzing the interference fringes at multiple angles using rotating mirrors to tilt the beam before it passes through the sample. They have been able to extend their technique to high speed and are now performing video rate optical tomography for cellular samples and show they can monitor the changes in a living cell as it is exposed to different chemicals.
BiOS2008HotTopics.jpg
The Hot Topics session during Photonics West's Biomedical Optics (BiOS) symposia always draws a standing-room-only crowd. (Photos courtesy SPIE)
During the BiOS Hot Topics session on Saturday night, a full-house crowd heard a series of expert reports that moderator Sergio Fantini of Tufts University characterized as "important advancements in medical treatments and diagnostics being made by the field of biomedical optics."

Among the highlights:
  • R. Rox Anderson, Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard School of Medicine, said that a deeper version of laser-guided fractional microbeam surgery methods now used in ophthalmology and dermatology provides a new paradigm for treatment of more deadly cancers; he also described the potential of low-light laser therapy in treating and preventing stroke damage.
  • Bruce Tromberg, Beckman Laser Institute and Medical Clinic, University of California Irvine, and Lihong Wang, Washington University in St. Louis, showed impressive positive impacts on the success of therapy as a result of enhanced data gathered during treatment by diffuse optical imaging at Beckman and by photoacoustic tomography and microscopy at Washington University.
  • David Piston, Vanderbilt University, described real-time quantitative microscopy at the nanometer scale that enables more focused therapies, and Mary-Ann Mycek, University of Michigan, showed how tissue optical spectroscopy is used in earlier, more accurate diagnosis and treatment of pancreatic disease.
  • Paul French, Imperial College, talked about work in fluorescence lifetime imaging that has been revolutionized by the supercontinuum source technology.
  • W. E. Moerner, Stanford University, described single-molecule superresolution imaging and trapping to control molecular activity, and Stefan Andersson-Engels, Lund University, reported on fiber-optic treatments for prostate and other cancers with considerably greater tissue penetration than current photodynamic therapies.
During the two-day Biomedical Optics exhibition, 150 companies displayed their latest products, components, and systems and gave BiOS conference attendees a focused look at the technologies aligned with their work.

For more information, visit: http://spie.org/pw


Published: January 2008
Glossary
adaptive optics
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it to experience distortions, resulting in image blurring and degradation in various optical applications, such as astronomical observations, laser communications, and imaging systems. Adaptive optics systems actively adjust the optical elements in real-time to compensate for these distortions. Key...
eye
The organ of vision or light sensitivity.
fluorescence
Fluorescence is a type of luminescence, which is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Specifically, fluorescence involves the absorption of light at one wavelength and the subsequent re-emission of light at a longer wavelength. The emitted light occurs almost instantaneously and ceases when the excitation light source is removed. Key characteristics of fluorescence include: Excitation and emission wavelengths: Fluorescent materials...
image
In optics, an image is the reconstruction of light rays from a source or object when light from that source or object is passed through a system of optics and onto an image forming plane. Light rays passing through an optical system tend to either converge (real image) or diverge (virtual image) to a plane (also called the image plane) in which a visual reproduction of the object is formed. This reconstructed pictorial representation of the object is called an image.
light
Electromagnetic radiation detectable by the eye, ranging in wavelength from about 400 to 750 nm. In photonic applications light can be considered to cover the nonvisible portion of the spectrum which includes the ultraviolet and the infrared.
microscope
An instrument consisting essentially of a tube 160 mm long, with an objective lens at the distant end and an eyepiece at the near end. The objective forms a real aerial image of the object in the focal plane of the eyepiece where it is observed by the eye. The overall magnifying power is equal to the linear magnification of the objective multiplied by the magnifying power of the eyepiece. The eyepiece can be replaced by a film to photograph the primary image, or a positive or negative relay...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
ophthalmology
Ophthalmology is a branch of medicine that focuses on the anatomy, physiology, and diseases of the eyes and visual system. Ophthalmologists are medical doctors who specialize in the diagnosis, treatment, and prevention of eye disorders and diseases. They are trained to provide comprehensive eye care, including medical, surgical, and optical interventions. Key areas within ophthalmology include: General eye care: Ophthalmologists perform routine eye examinations to assess visual acuity,...
phonon
A phonon is a quantum of vibrational energy associated with the periodic motion of atoms or molecules in a crystalline lattice. In simpler terms, phonons are quanta of lattice vibrations in a solid material. They represent the collective vibrational modes of atoms or groups of atoms in a crystal lattice and play a crucial role in understanding the thermal and mechanical properties of materials. Key points about phonons include: Quantization of vibrational energy: Similar to photons for...
photon
A quantum of electromagnetic energy of a single mode; i.e., a single wavelength, direction and polarization. As a unit of energy, each photon equals hn, h being Planck's constant and n, the frequency of the propagating electromagnetic wave. The momentum of the photon in the direction of propagation is hn/c, c being the speed of light.
photonics
The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
retina
1. The photosensitive membrane on the inside of the human eye. 2. A scanning mechanism in optical character generation.
superresolution
Superresolution refers to the enhancement or improvement of the spatial resolution beyond the conventional limits imposed by the diffraction of light. In the context of imaging, it is a set of techniques and algorithms that aim to achieve higher resolution images than what is traditionally possible using standard imaging systems. In conventional optical microscopy, the resolution is limited by the diffraction of light, a phenomenon described by Ernst Abbe's diffraction limit. This limit sets a...
adaptive opticsAObiomedical opticsBiophotonicsBiOsBrillouincancerchemicalsenergyeyefluorescenceimagelenseslightmicroscopeMicroscopynanoNews & FeaturesOCTophthalmologyoptical tomographyphononphotonphotonicsPhotonics WestretinaspectroscopysuperresolutionLasers

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