news digest ♦ Lasers
Bomb detecting lasers could improve security checkpoints
Michigan State University research has put the possibility of bomb-detecting lasers at security checkpoints within reach
In the current issue of Applied Physics Letters, Marcos Dantus, MSU chemistry professor and founder of BioPhotonic Solutions, has developed a laser that can detect micro traces of explosive chemicals on clothing and luggage.
“Since this method uses a single beam and requires no bulky spectrometers, it is quite practical and could scan many people and their belongings quickly,” Dantus comments. “Not only does it detect the explosive material, but it also provides an image of the chemical’s exact location, even if it’s merely a minute trace on a zipper.”
This doesn’t mean that security forces will be armed with handheld laser in airports, however. This laser would more likely be in a conveyor belt, like the X-ray scanners already used for airport security. The low-energy laser is safe to use on luggage as well as passengers, he adds.
For decades, scientists have been working to develop lasers that are powerful enough for detection, but safe enough to use on people. Dantus’ initial spark for this breakthrough came from collaboration with Harvard University that developed a laser that could be used to detect cancer, but has the beam output of a simple presentation pointer.
“While working on biomedical imaging, I began exploring additional applications,” Dantus says. “We soon learned how effective it was for detecting traces of hazardous substances from distances up to 10 metres away.”
Dantus’ bomb-detecting laser works as a single beam, but uses two pulses. The first resonates with certain chemical frequencies found in explosives. The second, a shadow pulse, serves as a reference. A discrepancy between the two pulses indicates the presence of explosive materials.
“The laser is not affected by the colour or surface of clothes or luggage,” Dantus says. “The resonant pulse and the shadow pulse are always in balance unless something is detected. Our method has Raman chemical specificity, excellent sensitivity and robust performance on virtually all surfaces.”
Not only does the laser detect explosive material, but it also provides an image of the chemical’s exact location, even if it’s merely a minute trace on a zipper. (Courtesy of MSU)
An aerospace company has already expressed interest in furthering this technology. With additional funding, a standalone prototype could be created in about one year, he adds.
This work is described in detail in the paper, “Standoff explosives trace detection and imaging by selective stimulated Raman scattering,” published online in Applied Physics Letters, 103, 061119 (2013). The full paper can be accessed via the website
http://dx.doi. org/10.1063/1.4817248
Funding for this research was provided by the Department of Homeland Security, Science and Technology Directorate. BioPhotonic Solutions is a high- tech company Dantus launched in 2003 to commercialise technology invented by his research group at MSU.
Nanoplus orders Oxford Instruments tool for laser etching
The Ionfab300 Plus will be used for laser bar facet coating with anti-reflective and high-reflection multilayers, and the PlasmaPro System100 RIE system will be used for GaAs and InP compound etching
Oxford Instruments Plasma Technology (OIPT) has just received an order from Nanoplus in Germany for an ion beam deposition and a plasma etch system for use on novel types of semiconductor laser production.
Nanoplus produces semiconductor lasers over several wavelength ranges (some exclusively) for many different customers with a wide range of applications.
The Ionfab300 Plus ion beam deposition is a multi- 98
www.compoundsemiconductor.net October 2013
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142