Detecting Alzheimer's in the eye, lifting fingerprints without touching the surface

09/21/05

Optics meeting to showcase state-of-the-art discoveries

September 21, 2005--Frontiers in Optics 2005--the 89th Annual Meeting of the Optical Society of America--will be held from October 16-20 in Tucson, Arizona, alongside Laser Science XXI, the annual meeting of the American Physical Society Division of Laser Science. Reporters interested in obtaining a badge for the meeting should contact Elizabeth Bowen at 410.821.8220, elizabethb@imrecommunications.com.

PLENARY SESSION HIGHLIGHTS: 100 YEARS OF EINSTEIN, ATTOSECOND-SPEED CAMERAS, AND IMAGES FROM SATURN MOON TITAN
At a plenary and awards session, five speakers will present topics that span numerous realms in cutting-edge optics. Stan Whitcomb of Caltech will celebrate the 100th anniversary of Albert Einstein's seminal paper on special relativity, which showed that the speed of light was the same for all observers, regardless of their own speeds. Ferenc Krausz of the Max Planck Institute for Quantum Optics and Ludwig-Maximilians-University, both located in Germany, will describe controlling and measuring processes on the time scale of the attosecond, or a billionth of a billionth of a second, a timescale important for the motion of electrons in the atom. Drawing from the NASA Huygens Probe's Descent Imager/Spectral Radiometer (DISR), Martin Tomasko of the University of Arizona in Tucson will present stunning images, recently captured in the Cassini mission to Saturn, of the mysterious moon Titan. Receiving OSA's Ives Medal, Theodor W. Hansch of the Max Planck Institute for Quantum Optics, who has made many important atomic measurements with world-record levels of detail, will discuss his "passion for precision." Texas A&M's Marlan O. Scully, the recipient of the 2005 APS Schawlow Prize, will describe theoretical connections between the quantum theory of lasers, black hole radiation and the ultracold gases known as Bose-Einstein condensates. (Monday, October 17, 8:30 AM)

Following are a few of the many technical highlights to be discussed at the meeting:

1. NON-INVASIVE OPTICAL TOOLS HOLD SIGNIFICANT PROMISE FOR DETECTING ALZHEIMER'S IN EARLY STAGES
2. OPTICAL METHOD LIFTS DETAILED FINGERPRINTS WITHOUT TOUCHING THE SURFACE
3. EXPLORING "LIVE" VIRTUAL REALITY
4. NEW OPTICAL TEST DETECTS COLON CANCER POTENTIALLY MUCH EARLIER THAN BEFORE
5. COMING SOON TO A THEATER NEAR YOU: NEW COMPUTER-GENERATED MOVIE BEAMS FULL RANGE OF NATURAL LIGHTING
6. SUPER LENSING IN THE MID-INFRARED
7. REAL-TIME, LASER-BASED SYSTEM FOR EXPLOSIVES DETECTION

1. NON-INVASIVE OPTICAL TOOLS HOLD SIGNIFICANT PROMISE FOR DETECTING ALZHEIMER'S IN EARLY STAGES

Building upon a stunning recent discovery that Alzheimer's disease can be detected early by looking for telltale proteins in the eye, researchers will present a pair of optical tests that can potentially diagnose the disease in its beginning stages. Such tests may not only improve patients' chances to start treatment earlier, but they could also speed development of new Alzheimer's drugs.

In a paper published in the journal Lancet, Lee Goldstein of Harvard Medical School and his colleagues showed that the exact same amyloid beta proteins which are a hallmark of Alzheimer's disease are also found in the lens and its surrounding fluid. In those portions of the eye, the proteins form amyloid deposits similar to those in the brain. Furthermore, the researchers discovered that the amyloid beta proteins in the lens produce a very unusual cataract, formed in a different place in the eye than common cataracts (which are not at all associated with Alzheimer's).

Working feverishly since their discovery, Goldstein and his colleagues will now present two optical tests for detecting these proteins. Using a technique known as quasielastic light scattering, the first test employs low-power infrared laser light to noninvasively detect protein particles in the specific part of the lens where these unusual cataracts form. The second test would be applied to those who screen positively for the proteins, in order to confirm an Alzheimer's diagnosis. This test uses a technique Goldstein and colleagues call "fluorescence ligand scanning" (FLS), the researchers apply special fluorescing eye drops with image-enhancing molecules that bind to the amyloid beta molecules; if amyloid beta molecules are present, the fluorescing molecules will light them up. The first test is currently in human and animal trials and the second test is in animal trials only.

These two diagnostic tests are envisioned to be a two-step process for screening and then confirming an Alzheimer's diagnosis. These new optical tools can also potentially speed up the development of new Alzheimer's drugs, by giving investigators rapid feedback on whether the drug is doing its job of removing the harmful proteins from the body. Moreover, the researchers are using the same technologies to develop new tests for rapidly detecting amyloid plaques resulting from prion diseases, including mad cow, scrapie in sheep, and Creutzfeldt-Jacob disease in humans. (Paper FTuBB4, Non-Invasive Optical Detection of Alzheimer's Disease -Amyloid in Human AD and Transgenic Mouse Lenses in vivo; Tuesday, October 18, 5:15 PM)

This work is funded by: National Institute of General Medical Sciences (NIH); National Institute on Aging (NIH); Beeson Scholars Program (American Federation for Aging Research); Alzheimer's Association; MA Lion's Eye Research Fund; Cooperative State Research, Education, and Extension Service, US Department of Agriculture (CSREES, USDA); and two anonymous donors.

2. OPTICAL METHOD LIFTS DETAILED FINGERPRINTS WITHOUT TOUCHING THE SURFACE

Optics researchers at the University of Pennsylvania have come up with a new light-based method of recording fingerprints at a crime scene without the use of chemicals or the need to make any kind of contact with the surface. While examiners presently rely on chemical reagents-- to one degree or another--for obtaining a fingerprint, the new method executes the often precarious task of lifting latent prints at a crime scene simply and noninvasively.

Using a standard light source, a polarizing filter similar to a sunglass lens, a digital camera and a computer to process the acquired data, researchers can detect, and record in fine detail, a latent fingerprint with at least as much precision and quality as is typically produced by conventional methods.

Because the system is completely chemical-free, it is devoid of treatments which often put the integrity of other simultaneously present forensic evidence at risk of contamination, including valuable DNA sources such as blood or saliva. Some traditionally tricky surfaces, like the sticky side of a tape that presents great difficulty for conventional methods like powdering, are actually cases in which the new method excels. Another advantage in using this technique of lifting fingerprints is that it is fast; while certain chemical-based methods can take hours or even days to develop the enhanced results, the new process obtains results in minutes.

While this new solution requires few pieces of equipment, its success depends upon the clever use of optics. By shining the light on the fingerprint at a special angle, and then positioning the polarizer so that reflected light passes through it, the polarizer will selectively darken either only the background or only the fingerprint mark area, thus increasing the contrast of the fingerprint mark against the background, making it visible to the eyes or to a recording camera. Like most other latent-fingerprinting techniques, the system does not work well on highly porous surfaces.

The fingerprinting method is only a laboratory device at present, though the researchers have applied for a patent on it. In the near future, the researchers plan to build a prototype that is both portable and inexpensive, something that they do not expect to be a major challenge. (Paper JWA57, Optical Non-Invasive Latent Fingerprint Lifting, Wednesday, October 19, 10 AM)

3. EXPLORING "LIVE" VIRTUAL REALITY

Optics is a scientific discipline but also an artistic endeavor, at least insofar as it contributes to aesthetic refinements (for example, the mathematical description of perspective in 15th-century Italy) or provides instrumentation for artists (such as the camera obscura, which projects images onto walls). In our own day, optics research can provide tools to enhance modern visual arts, which include virtual reality and other interactive video.

One artist/researcher, Michael Naimark, a Visiting Associate Professor in the Interactive Media Division of the USC School of Cinema/Television, strives to enhance the way viewers apprehend the "sense of place" in interactive video displays. As Naimark points out, present-day webcams contradict the intended effects of virtual reality, which aims to immerse a viewer fully in another setting. In general, webcams currently transmit low-resolution pictures over the Internet and therefore do not draw in a viewer very strongly.

Naimark has explored the concept of "virtual-reality webcams" by assembling low-res video sent over the Internet into panoramic video of a place (for an example filmed in Jerusalem, see http://www.naimark.net/images/vrwebcam/jer%20truckcomp.mov). Such a display, according to Naimark, can give the viewer a better sense of that location.

In addition, Naimark has produced "moviemaps," video presentations in which the viewer can "travel" through a pre-recorded route. For example, a moviemap of Banff, in the Canadian Rockies (see second half of http://www.naimark.net; paper FMD1, (Re)Presenting Place: Some Experimental Art Projects, Monday, October 17, 3:45 PM)

4. NEW OPTICAL TEST DETECTS COLON CANCER POTENTIALLY MUCH EARLIER THAN BEFORE

Colon cancer will be diagnosed in approximately 140,000 Americans this year, leading to 50,000 deaths. Now, Young Kim, Vadim Backman and their colleagues at Northwestern University in Evanston, IL have developed an optical probe that has shown signs of detecting colon cancer far earlier than any existing method.

In the new technique, called LEBS (low-coherence enhanced backscattering), researchers shine light on the colon and detect the light that bounces directly back (backscatters) from the tissue. The intensity of backscattered light provides information on the colon tissue's degree of disorder, which differs for normal and cancerous tissue. The backscattered light's spectrum also provides information on the tissue's structure and biochemical composition, which can further distinguish cancerous cells from normal ones.

In a pilot study of 100 human subjects, LEBS detected colon cancer with an accuracy of 90%. Animal studies demonstrated that LEBS detected pre-cancerous colon tissue far earlier than colonoscopy and other techniques, including those that search for currently known molecular markers for the disease. The researchers are currently conducting larger-scale human trials and working to develop a small fiber-optic probe that can carry out LEBS measurements.

The researchers envision that LEBS could become a part of an annual exam from a primary care physician, to detect very early signs of colon cancer and determine the need for more expensive tests such as colonoscopy. The cost of colonoscopy makes it impossible for all Americans who are at risk (more than 60 million people over age 50) to get the test on a regular basis, and the price of detecting colon cancer in a single patient is over $1,000,000.

Therefore, the researchers hope LEBS can serve as a screening tool that will identify all those who require a full colon examination with colonoscopy, which remains the gold standard for colon cancer screening. (Paper FMC4, Low-Coherence Enhanced Backscattering (LEBS) for Colon Cancer Screening, Monday, October 17, 2:45 PM)

5. COMING SOON TO A THEATER NEAR YOU: NEW COMPUTER-GENERATED MOVIE BEAMS FULL RANGE OF NATURAL LIGHTING

Anyone who has seen a recent summer blockbuster has witnessed the dramatic increase in computer-generated realism in recent years. Driving this increase in realism has been computer graphics (CG) techniques for simulating how light travels within a scene and how it reflects from surfaces. However, CGI movies have not fully exploited the entire scope or "dynamic range" of lighting that exists in real life, from the first light at dawn to the blinding light of the midday sun.

Paul Debevec of the University of Southern California Institute of Creative Technologies will demonstrate a method to capture the complete range of illumination we experience in the real world. First, he uses a "High Dynamic Range" imaging technique to capture the lighting conditions within a scene. Using the measurements of these real-world illuminations, he then applies these lighting conditions to synthetic objects, such as gleaming spheres in a CG version of St. Peter's Basilica, using a technique called Image-Based Lighting.

Elements illuminated in this way include the transforming mutants in X-Men and X-Men 2, virtual cars and stunt actors in The Matrix Reloaded, and whole cityscapes in The Time Machine. In Debevec's most recent works, the techniques were used to full range for an outdoor illumination environment--from the pre-dawn sky to a direct view of the sun--to illuminate a virtual 3D model of the Parthenon on the Athenian Acropolis. (Paper FMD2, Capturing and Simulating Physically Accurate Illumination in Computer Graphics, Monday, October 17, 4:15 PM)

6. SUPER-LENSING IN THE MID-INFRARED

Physicists at the University of Texas in Austin have made a "super lens," a flat lens that can image a point source of light down to a focused spot only one-eighth of a wavelength wide; this is the first time such super lensing has been accomplished in a functional device in the mid-infrared range of the electromagnetic spectrum.

Historically, lensing required a lens-shaped (that is, lozenge-shaped) optical medium for bringing the diverging rays coming from a point source into focus on the far side of the lens. But in recent years, researchers have found that in "negative permittivity" materials (in which a material's response to an applied electric field is opposite that of most normal materials), light rays can be refracted in such a way as to focus planar waves into nearly a point, though over a very short region, usually only a tenth or so of the wavelength of the light. Such near-field optics are not applicable for such uses as reading glasses or telescopes, but have become an important technique for certain kinds of nanoscale imaging of large biological molecules than can be damaged by UV light.

The micron-sized Texas lens consists of a silicon carbide membrane in between layers of silicon oxide. It focuses 11-micron-wavelength light, but the researchers hope to push on into the near-infrared range soon. Furthermore, the lensing effect seems to be highly sensitive to the imaging wavelength and to the lens thickness. Team leader Gennady Shvets says that additional possible applications of the lens include direct laser nanolithography and making tiny antennas for mid-IR-wavelength free-space telecommunications. (Lab website: www.ph.utexas.edu/~shvetsgr/; Paper FMG2, Phononic Nanophotonics: Super-Lensing in Mid-IR, Monday, October 17, 4:15 PM)

7. REAL-TIME, LASER-BASED DETECTION SYSTEM FOR EXPLOSIVES DETECTION

In response to the London train bombing and similar incidents, researchers are busily developing an arsenal of laser techniques for detecting explosives in various situations. Rosario Sausa of the Army Research Laboratory in Aberdeen Proving Ground, MD will present a new laser technique that can potentially be deployed to detect tiny traces of explosives on surfaces (such as a bomber's clothes or the doors of a truck) in mass transit and airport settings.

Called Surface Laser Photofragmentation-Fragment Detection Spectroscopy (SLP-FD), the laser system breaks up molecules on a surface and creates fragments of nitric oxide (NO), which is present at various levels in different explosives. A laser then ionizes the NO molecules, so that they become electrically charged and fly towards a detector where they are counted. By measuring the levels of NO fragments, the researchers demonstrated that the technique could detect and identify various high explosives such as TNT, RDX, HMX, and CL2O at trace concentrations, in the range of nanograms per square centimeter.

Like most other methods, SLP-FD cannot detect explosives hidden under the surface (though detectable traces of explosive usually find their way unavoidably on a bomber's clothing and trucks). Compared to other techniques, SLP-FD can find explosives that have not drifted in detectable quantities into the air. In addition, the technique can distinguish between the NO fragments generated on a surface from gaseous NO, should it be present in air, and air does not interfere with the measurement (unlike some other laser-based techniques available).

The SLP-FD system is still in the research stage, in a laboratory environment with a 3-foot by 4-foot laser costing about $100,000. With continued development and advances in laser technology, the researchers believe that a handheld or portable system, using one laser for both fragmentation and ionization, can be made for between $25,000 and $50,000. (Paper FThX6, Real-Time Detection of Explosive Residues by Surface Laser Photofragmentation-Fragment Ionization Spectroscopy, Thursday, October 20, 2:30 PM)

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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