Invisible cloak…

Cloak of Invisibility: Engineers Use Plasmonics to Create an Invisible Photodetector

12:08:44 AM, Wednesday, May 23, 2012

“(ScienceDaily May 21, 2012) – It may not be intuitive, but a coating of reflective metal can actually make something less visible, engineers at Stanford and UPenn have shown. They have created an invisible, light-detecting device that can “see without being seen.”

At the heart of the device are silicon nanowires covered by a thin cap of gold. By adjusting the ratio of metal to silicon — a technique the engineers refer to as tuning the geometries — they capitalize on favorable nanoscale physics in which the reflected light from the two materials cancel each other to make the device invisible.

Pengyu Fan is the lead author of a paper demonstrating the new device published online May 20th in the journal Nature Photonics. He is a doctoral candidate in materials science and engineering at Stanford University working in Professor Mark Brongersma’s group. Brongersma is senior author of the study.

Cloak of invisiblity

Light detection is well known and relatively simple. Silicon generates electrical current when illuminated and is common in solar panels and light sensors today. The Stanford device, however, is a departure in that for the first time it uses a relatively new concept known as plasmonic cloaking to render the device invisible. . .”

READ HERE

About Tom Harley

Amateur ecologist and horticulturalist and CEO of Kimberley Environmental Horticulture Inc. (Tom Harley) Kimberley Environmental Horticulture Incorporated Kimberley Environmental Horticulture (KEH) is a small group of committed individuals who promote the use of indigenous plants for the landscaping of parks and gardens. Rehabilitation of Kimberley coast, bushland and pastoral regions are also high on our agenda. This includes planting seedlings, weed control, damage from erosion or any other environmental matter that comes to our attention. We come from all walks of life, from Professionals and Trades oriented occupations, Pensioners and Students, Public Servants and the Unemployed. We have a community plant nursery where we trial many old and new species, with a view to incorporating these into our landscaping trials. Our labour force are mainly volunteers, but with considerable help from the 'work for the dole' program, Indigenous Community Development Employment Program (CDEP) groups and the Ministry of Justice, with their community work orders; in this way we manage to train many people in the horticultural skills needed for indigenous plant growing. We constantly undertake field trips that cover seed and plant collection in the Kimberley. Networking around the Kimberley region and the east Pilbara is a necessary part of promoting our activities. We consult on a range of Environmental and Landscaping matters that deal with our region. Our activities involve improving Broome's residential streetscapes by including 'waterwise' priciples in planting out nature strips. Sustainable environmental horticulture is practised by members of our group. We use existing vegetation as the backbone of any plantings, using these species to advantage when planning to develop tree forms or orchards. The Broome region is sensitive to development. Subsequently many weed species have become dominant in and around developed areas. The use and movement of heavy machinery is the biggest single cause of environmental degradation. We dont live in a 'Tropical Paradise' but on the edge of the Great Sandy Desert. The plants that survive best here, grow in well-drained pindan sand, and are found from the Dampier Peninsular southward to where average rainfall is below 600mm. When we use rainforest species, detail is important when planting, water catchment, sunlight and understorey species are all considered. The use of recycled 'grey' water is an advantage here as well as treated waste-water, although many local species do not fare well with nutrients from this source. We use waterwise planting methods which include harvesting asmuch rainwater as possible, with swales designed to hold up to 200 litres, to help recharge the local groundwater aquifer. There has been a serious decline in this aquifer over the last few years. With the fast expansion of the Broome peninsular, more and more land is being covered by concrete, iron and bitumen so that much less water is available to replenish the aquifer, allowing the salt content to become significantly higher. The small Broome Peninsular is on the south-western corner of the Dampier Peninsular (bound by Broome, Derby and Cape Leveque at the northern tip). Compaction by vehicles also inhibits water retention due to the content of our local pindan sand, hard as concrete in the dry, going to soft and sloppy mud after rain. None of us are botanists, inevitably we have got some names wrong, names changed, or have not gone to sub-species level. If you note a photo or description may be wrong, please e-mail to kimenvhort@yahoo.com.au
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