Surface enhanced Raman spectroscopy has become a viable technique for the detection of single molecules. This highly sensitive technique is due to the very large (up to 14 orders in magnitude) enhancement in the Raman cross section when the molecule is adsorbed on a metal nanoparticle cluster. We report here SERS (Surface Enhanced Raman Spectroscopy) experiments performed by adsorbing analyte molecules on nanoscale silver particle clusters within the gelatin layer of commercially available holographic plates which have been developed and fixed. The Ag particles range in size between 5 - 30 nanometers (nm). Sample preparation was performed by immersing the prepared holographic plate in an analyte solution for a few minutes. We report here the production of SERS signals from Rhodamine 6G (R6G) molecules of nanomolar concentration. These measurements demonstrate a fast, low cost, reproducible technique of producing SERS substrates in a matter of minutes compared to the conventional procedure of preparing Ag clusters from colloidal solutions. SERS active colloidal solutions require up to a full day to prepare. In addition, the preparations of colloidal aggregates are not consistent in shape, contain additional interfering chemicals, and do not generate consistent SERS enhancement. Colloidal solutions require the addition of KCl or NaCl to increase the ionic strength to allow aggregation and cluster formation. We find no need to add KCl or NaCl to create SERS active clusters in the holographic gelatin matrix. These holographic plates, prepared using simple, conventional procedures, can be stored in an inert environment and preserve SERS activity after several weeks subsequent to preparation.
The San Jose State University Physics Department, located in Silicon Valley, provides students with a high quality education in optics and provides local high-tech industry and government laboratories with a partner for optics- related research and development projects. There are approximately 50 undergraduate majors and 20 graduate (M.S.) students in the Department. Core courses leading to the B.S. in Physics are offered with upper division courses in Modern Optics, Lasers and Applications, Advanced Optics Lab, Advanced Instrumentation Lab, and Individual Studies as well as graduate courses in Electro-optics, Graduate Optics, Optical Metrology, and Laser Spectroscopy. Graduates are well prepared to enter the lasers and optics industry or go onto graduate school. A 4000 square-foot lab in the Science Building houses the Institute for Modern Optics, an organized research unit in the College of Science. One of the major goals of the Institute is to facilitate collaborative research between the local optics industry and the faculty and students at SJSU. The Department is presently developing a new biophotonics lab for single molecule studies with a dual beam optical tweezers already operational. A National Science Foundation Research Experience for Undergraduates Program grant provides research support for undergraduates.
This is an improved version of the prism fingerprint sensor described in an earlier paper by Bahuguna et. al.1. The new design uses a modified holographic grating glued to a right-angled truncated prism and is more compact than the previous one.
A prism fingerprint sensor is described which uses a holographic grating glued to a right angled prism. The quality of the fingerprint is very good; the pores on the ridges can be seen.
Character recognition by matched filtering is almost impossible to accomplish without the use of a liquid gate when the object to be recognized is on a transparency. This paper suggests a simple method to overcome this problem. A practical application to fingerprint recognition is discussed.
Located in high-tech "Silicon Valley," California, San Jose State University is ideally suited to provide students with a high quality education in optics, and industry with a partner for optics related research and development projects. There are 130 undergraduate majors and 65 graduate (M.S.) students in the Physics Department. For the past five years the Department has offered a special program leading to the B.S. in Physics with a Concentration in Lasers and Optics. Students take the usual core undergraduate Physics courses plus upper division courses in Modem Optics, Lasers and Applications, Advanced Optics Lab, Advanced Lasers Lab, Advanced Instrumentation Lab, and either Individual Studies or a graduate course in Electro-optics, Graduate Optics, Optical Metrology, or Laser Spectroscopy. Graduates are well prepared to enter the lasers and optics industry or go on to graduate school. Recently, a 4000 square foot area in the Science Building has been renovated to house the new Institute for Modem Optics, an organized research unit in the College of Science. One of the major goals of the Institute is to facilitate collaborative research between the local optics industry and the faculty and students at SJSU. The Institute is well equipped with lasers, optical instrumentation, electronics/computers, and about 10 optical tables. A National Science Foundation Research Experience for Undergraduates Program grant provides research support in optics for about eight undergraduates at any time throughout the calendar year. The National Science Foundation also provides support for "Laser Applications in Science Education," a summer program that provides hands-on experience with lasers for high school science teachers.
Yeast and bacteria growth has been detected by observing light diffracted from specially prepared diffracting
screens upon which these organisms were grown. The screens were fabricated by impressing patterns on the
surface of a growing medium. As the microbes metabolized, they caused severe changes in the lightdiffracting
properties of the patterns as they ate into them. Such changes were detected within twenty
minutes for bacteria and ten minutes for yeast.
Yeast and bacteria growth has been detected by observing light diffracted from specially prepared diffracting
screens upon which these organisms were grown. The screens were fabricated by impressing patterns on the
surface of a growing medium. As the microbes metabolized, they caused severe changes in the lightdiffracting
properties of the patterns as they ate into them. Such changes were detected within twenty
minutes for bacteria and ten minutes for yeast.
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