Lasers Aim to Replace Scalpels in Cutting-Edge Biopsy Technique
05-16-19
Professor Lihong Wang and Postdoctoral Scholar Dr. Junhui Shi have developed a new imaging technique that uses pulses from two kinds of lasers to take pictures of microscopic biological structures. This new approach, called ultraviolet-localized mid-infrared photoacoustic microscopy, or ULM-PAM, develops images of the microscopic structures found in a piece of tissue by bombarding the sample with both infrared and ultraviolet laser light. "Because ultraviolet light and infrared have different properties, we had to find special mirrors and glass that could focus both," Dr. Shi says. "And because no camera exists that can see both, we had to develop ways to see if they were correctly focused." [Caltech story]
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Lihong Wang
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Junhui Shi
Popping Microbubbles Help Focus Light Inside the Body
12-03-15
Changhuei Yang, Professor of Electrical Engineering, Bioengineering, and Medical Engineering, and his postdoctoral colleague Dr. Haowen Ruan have developed a novel technique called time-reversed ultrasound microbubble encoded (TRUME) that uses gas-filled microbubbles to focus light inside tissue. "Ultrasound and X-ray techniques can only detect cancer after it forms a mass," Yang says. "But with optical focusing, you could catch cancerous cells while they are undergoing biochemical changes but before they undergo morphological changes." [Caltech story]
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Changhuei Yang
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A New Tool for Secret Agents—And the Rest of Us
12-10-12
Ali Hajimiri, Thomas G. Myers Professor of Electrical Engineering, and Postdoctoral Scholar in Electrical Engineering, Kaushik Sengupta, have developed tiny inexpensive silicon microchips that generate terahertz (THz) waves that fall into a largely untapped region of the electromagnetic spectrum and that can penetrate a host of materials without the ionizing damage of X-rays. When incorporated into handheld devices, the new microchips could enable a broad range of applications in fields ranging from homeland security to wireless communications to health care, and even touchless gaming. "This extraordinary level of creativity, which has enabled imaging in the terahertz frequency range, is very much in line with Caltech's long tradition of innovation in the area of CMOS technology," says Chair Ares Rosakis. "Caltech engineers, like Ali Hajimiri, truly work in an interdisciplinary way to push the boundaries of what is possible." [Caltech Release]
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Ali Hajimiri
Kaushik Sengupta
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Point of Light
12-07-12
Hyuck Choo, Assistant Professor of Electrical Engineering, and Postdoctoral Scholar Myung-Ki Kim have invented a light-focusing device that may lead to applications in computing, communications, and imaging. This new kind of waveguide is made of amorphous silicon dioxide and is covered in a thin layer of gold. Just under two microns long, the device is a rectangular box that tapers to a point at one end. With the new device, light can ultimately be focused in three dimensions, producing a point a few nanometers across, and using half of the light that's sent through, Choo says. (Focusing the light into a slightly bigger spot, 14 by 80 nanometers in size, boosts the efficiency to 70 percent). The key feature behind the device's focusing ability and efficiency, he says, is its unique design and shape. [Caltech Release and Video]
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Hyuck Choo
Myung-Ki Kim
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