24 June 2016
Meanwhile, cities and towns across the globe enthusiastically switch to LED street lighting. The energy savings are significant, but in news reports of the plans and projects, there is usually no mention of the technical specifics (or “warmth”) of the light. Early bright white LED streetlights were mostly above 4000K, whereas warmer versions are now available, 3000K or below.
One problem with extremely bright light is that it impairs vision in darker areas, so any illusion of safety at night vanishes as visibility diminishes once you get into a shadow. For drivers as well as pedestrians, this can be dangerous.
Now the American Medical Association (AMA) has issued guidance encouraging communities to adopt LED lighting that minimizes blue-rich light. The AMA also recommended that “all LED lighting should be properly shielded to minimize glare and detrimental human health and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods,” according to a press release.
“The guidance adopted by grassroots physicians who comprise the AMA's policy-making body strengthens the AMA's policy stand against light pollution and encourages public awareness of the adverse health and environmental effects of pervasive nighttime lighting,” the release says.
We requested a copy of the original report that led to these recommendations from the AMA. Here’s an excerpt:
More recently engineered LED lighting is now available at 3000K or lower. At 3000K, the human eye still perceives the light as “white,” but it is slightly warmer in tone, and has about 21% of its emission in the blue-appearing part of the spectrum. This emission is still very blue for the nighttime environment, but is a significant improvement over the 4000K lighting because it reduces discomfort and disability glare. Because of different coatings, the energy efficiency of 3000K lighting is only 3% less than 4000K, but the light is more pleasing to humans and has less of an impact on wildlife.
“Disability glare” is defined by the Lighting Research Center at Rensselaer Polytechnic Institute as “the reduction in visibility caused by intense light sources in the field of view [because of] stray light being scattered within the eye.”
One city that put the brakes on the brighter LEDs is Davis, California. In 2014, as new lights were being installed, the Davis city council put the project on hold after multiple complaints from residents. Later, the city decided to spend an additional $325,000 to replace those too-bright streetlights in residential areas. However, Davis is the exception. Places that have not yet committed to the switch are encouraged by the International Dark-Sky Association (IDA), the Lighting Research Center, and others to ask the right questions and study the issues involved beyond the simple let’s-save-energy approach. (In fact, that justification is up for debate as well -– it seems that when something gets cheaper, people tend to use more of it.)
Last fall, SPIE Newsroom published an article exploring these issues and collecting the advice of lighting experts. Recommendations for municipalities considering a change are included. (See “LED light pollution: Can we save energy and save the night?” by Mark Crawford.)
Just this month, a world atlas of artificial sky luminance, described in Science Advances reported that 80% of North Americans and one third of all humans are unable to see the Milky Way because of light pollution. Calculated with data from professional researchers and citizen scientists, the atlas also takes advantage of the newly available, low-light imaging data from the VIIRS DNB sensor on the Suomi National Polar-orbiting Partnership (NPP) satellite. The authors conclude:
"Light pollution needs to be addressed immediately because, even though it can be instantly mitigated (by turning off lights), its consequences cannot (for example, loss of biodiversity and culture)."
The IDA says this is a "watershed moment." The sky atlas and the AMA recommendations offer "an unprecedented opportunity to implore cities to transition to LEDs in the most environmentally responsible way possible." It's a good chance to start a conversation with your elected officials.
07 June 2016
|Simon Blackmore talks about farming with robots|
for precision agriculture in an
SPIE Newsroom video interview [6:58].
Now, he said in an SPIE Newsroom video interview posted last week, they’re asking questions about how robotics and other photonics-enabled technologies can help save energy and money, minimize soil damage, and improve crop yield.
Blackmore, who is Head of Engineering at Harper Adams University in Shropshire, director of the UK National Centre for Precision Farming (NCPF), and project manager of FutureFarm, also shared his ideas in a new conference at SPIE Defense and Commercial Sensing in April on technologies with applications in precision agriculture.
Blackmore and his NCPF colleagues are working to overhaul current farming practices by intelligently targeting inputs and energy usage. Their lightweight robots are capable of planting seeds in fields even at full moisture capacity, replacing heavy tractors that compact and damage the soil.
“Now one of my former PhD students has developed a laser weeding system that probably uses the minimum amount of energy to kill weeds, by using machine vision to recognize the species, biomass, leaf area, and position of the meristem, or growing point,” Blackmore said.
A miniature spray boom of only a few centimeters wide can then apply a microdot of herbicide directly onto the leaf of the weed, thus saving 99.9% by volume of spray. Or, a steerable 5W laser can heat the meristem until the cells rupture and the weed becomes dormant. These devices could be carried on a small robot no bigger than an office desk and work 24/7 without damaging the soil or crop.
Not surprisingly, data is a hot topic in the field of precision agriculture.
Several speakers at the April event — among them John Valasek, and Alex Thomasson of Texas A&M University (TAMU), chairs of the conference, and Elizabeth Bondi of the Rochester Institute of Technology (RIT) — spoke about best practices for collecting data, and Kern Ding of California State Polytechnic University discussed data processing techniques.
Valasek also described several sensors and different ways they may be flown. Factors such as weather, speed, altitude, and frame rate can dramatically change the quality of the data products from UAV imagery.
Bondi discussed the calibration of imagery from UAVs (unmanned aerial vehicles, such as drones) to maintain consistency over time and under different illumination conditions.
Other speakers — Haly Neely of TAMU, Carlos Zuniga of Washington State University, and Raymond Hunt of the U.S. Agricultural Research Service — focused on the use of UAVs for such applications as soil variability, irrigation efficiency, insect infestation, and nitrogen management for crops including cotton, grapes, and potatoes.
Plant phenotyping — the analysis of crop characteristics such as growth, height, disease resistance, nutrient levels, and yield — is vital to increase crop production. Taking these data with current methods can damage plants, and is time-consuming and expensive. UAVs, carrying the right sensors, have the potential to make phenotyping more efficient and less damaging.
Speakers Yu Jiang of the University of Georgia, Andrew French of the U.S. Arid-Land Agriculture Research Center, and Grant Anderson of RIT described ground-based systems to expedite phenotyping, and Joe Mari Maja of Clemson University, Yeyin Shi of TAMU, Maria Balota of Virginia Polytechnic Institute, and Lav Khot of Washington State University discussed UAV-based systems.
With images and measurements from such devices, for example, cotton height may be determined and cotton bolls counted, soil temperature can be mapped, and nutrient levels in wine grapes were assessed remotely.
Small- and mid-sized farms are expected to see the largest yield increase from these initiatives. The ultimate result of all this photonics-enabled precision agriculture is profound: healthier food, more productive farms and gardens, and more nutritious food for a growing world population.
Thanks to Elizabeth Bondi and Emily Berkson, both of RIT, for contributions to this post.
Thanks to Elizabeth Bondi and Emily Berkson, both of RIT, for contributions to this post.
06 April 2016
On left, the patient’s left eye has no cataract and all structures are visible. On right, retinal image from fundus camera confirms the presence of a cataract. (From Choi, Hjelmstad, Taibl, and Sayegh, SPIE Proc. 85671Y, 2013)
Article by guest blogger Roger S. Reiss, SPIE Fellow and recipient of the 2000 SPIE President's Award. Reiss was the original Ad Hoc Chair of SPIE Optomechanical Working Group. He manages the LinkedIn Group “Photonic Engineering and Photonic Instruments.”
The human eye and its interface with the human brain fit the definition of an "instrument system." The human eye by itself is also an instrument by definition.
After the invention of the microscope and the telescope, the human eye was the first and only detector for hundreds of years, only to be supplemented and in most cases supplanted by an electro-optical detector of various configurations.
The evolution of the eye has been and still is a mystery. In National Geographic (February 2016) an excellent article titled "Seeing the Light" has a very good explanation of the eye's development.
Having recently had cataract surgery, my interest in the eye was stimulated. First, I wondered why "cataract surgery" is called "cataract surgery."
In cataract surgery, no surgery is performed on the cataracts (cataract material). A very small incision is made in the lens pocket and the cataract material is flushed out by using the opening to introduce the flushing substance, and the flushing substance carries out the cataract material through that opening. The cataract material may require ultrasonic fracturing to reduce particle size. A man- and machine-made lens is inserted into the opening. The opening may or may not require suturing. This procedure should more accurately be known as "lens replacement surgery."
Why are a large number of measurements made on the eye before the eye surgery?
Without invasion of the eyeball, a great many measurements from outside it must be made to determine the required focal length of the replacement lens. (Some people do need corrective glasses to achieve the correct value.) When I asked about all these measurements (made by high-precision lasers) other important factors were brought up, including knowledge of the instruments by the operator, guesswork, and finally…some luck. Luckily, without glasses distance vision is infinite after surgery, but reading glasses are a necessity. Today, there are many options available to cataract patients, including multifocal lenses, which may enable complete independence from glasses.
After having lens replacement surgery myself, two haunting questions remain unanswered in my mind.
A. Where did the optical-quality fluid (vitreous) in the original eye lens and the eyeball come from, and how did it know where it belonged? Optical-quality liquid or gel occurs in the human eye but nowhere else in the human body.
B. How did the Creator (or whoever or whatever, a religious question) -- without Physics 101 or Optics 101 or Warren Smith's book on basic optics -- determine the focal length of the eye lens (the distance from the eye lens to the retina; some people do need corrective glasses to achieve the correct value). The focal length of the human eye lens is a mathematical value based on measurements and calculations or both and could not have just evolved without some knowledge and information about basic optics.
I wish I could answer either of these two questions but I will have to wait for someone smarter than me. Until then let’s at least change the name of the operational procedure to reflect what is actually being performed, so that people will understand that their cataracts are not being operated on but that their eye lens is being replaced.
Meanwhile, beyond these everyday procedures for improving vision, exciting advances are emerging from labs around the world, enabled by photonics. These include smart contact lenses for monitoring and even treating disease. Artificial retinas under development at Stanford, USC, and elsewhere offer the promise of vision to the blind. The results might not be as clear as what we are used to (yet), but imaging technologies and/or nanomaterials that send visual signals to the brain are helping counter the effects of age-related macular degeneration and other vision problems. New devices and treatments may offer a bright future to those with previously intractable vision problems.
09 March 2016
|In existing technologies, 2D technologies can be introduced|
into products such as silicon electronics, semiconductor
nanoparticles, plastics and more for added new
functionality; above; a flexible 2d prototype sensor.
Graphene, anticipated as the next "killer" app to hit optical sensing, is expected to offer an all-in-one solution to the challenges of future optoelectronic technologies, says Frank Koppens. A professor at the Institute of Photonic Sciences (ICFO) in Barcelona, Koppens leads the institute's Quantum Nano-Optoelectronics Group.
Koppens, along with Nathalie Vermeulen of B-PHOT (Brussels Photonics Team, Vrije Universiteit Brussel), will lead a daylong workshop in Brussels on 5 April on transitioning graphene-based photonics technology from research to commercialization.
In his article on Light and Graphene in the current issue of SPIE Professional magazine, Koppens describes the 2D material's tunable optical properties, broadband absorption (from UV to THz), high electrical mobility for ultrafast operation, and novel gate-tunable plasmonic properties.
Two-dimensional materials-based photodetectors are among the most mature and promising solutions, Koppens notes. Potential applications include expanded communications networking and data storage, increased computing speeds, enhanced disease control utilizing increasingly larger and more complex data sets, and more accurate fire, motion, chemical, and other sensor systems including the next generation of wearables.
Graphene is gapless, absorbing light in the ultraviolet, visible, short-wave infrared, near-infrared, mid-infrared, far-infrared, and terahertz spectral regimes. A few of many advantages include:
- Ability to be monolithically integrated with silicon electronics
- Extremely fast -- exceeding 250GHz -- as a material-based photodetector
- Able to bend, stretch, and roll while maintaining useful properties
- Low-cost production with potential to integrate on thin, transparent, flexible substrates
- Potential to be competitive against alternate applications in health, safety, security and automotive systems.
Koppens notes that the €1 billion European Union Graphene Flagship program is aiming to work through academia and industry to bring graphene into society within the next 10 years.
For more, read the complete article in the SPIE Professional, and watch Koppens' SPIE Newsroom video interview [7:09] on manipulating light with graphene.
08 February 2016
For the first time, scientists have observed gravitational waves, ripples in the fabric of spacetime arriving at Earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 general theory of relativity and opens an unprecedented new window to the cosmos.
The discovery was announced on 11 February at a press conference in Washington, DC, hosted by the National Science Foundation, the primary funder of the Laser Interferometer Gravitational Wave Observatory (LIGO).
The gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.
The event took place on 14 September 2015 at 5:51 a.m. EDT (09:51 UTC) by both of the twin (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington. The LIGO observatories are funded by the National Science Foundation (NSF), and were conceived, built and are operated by the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT).
Earlier this week (on 8 February), we wrote:
Gravitational wave rumors pulsate through media
The cosmic rumor mill has been busy lately with tweets and lots of buzz about a potential announcement of observation of gravitational waves by the Laser Interferometer Gravitational Wave Observatory (LIGO). Predicted by Einstein 100 years ago, gravitational waves are ripples in space-time caused by collisions of massive objects like black holes and neutron star.
The LIGO interferometers in Louisiana and Washington State were just retooled, based on what researchers learned from their first few years of observations from 2002 to 2010. They are already several times more sensitive, and as the instruments are tuned to design sensitivity, they will be even better. According to some reports, their first observing run may have already found something. We’ll know on 11 February and we will update this post after that. Until then, see these reports:
The SPIE Newsroom visited LIGO Hanford Observatory last fall, just after the first observing run began for Advanced LIGO. In the following video, observatory Head Frederick Raab and LIGO Hanford Lead Scientist Mike Landry introduce us to the instrumentation and setup of LIGO Hanford, from the laser whose beam travels through the 4-km tubes of LIGO, to the stabilization needed for the interferometer’s mirrors:
25 January 2016
Sci-fi meets reality in this 1975 NASA photo: The Shuttle Enterprise rolls out of its Palmdale, California, manufacturing facilities with Star Trek television cast members on hand for the ceremony. From left to right are James Fletcher (NASA), DeForest Kelley (“Dr. ‘Bones’ McCoy”), George Takei (“Mr. Sulu”), James Doohan (“Chief Engineer Montgomery ‘Scotty’ Scott”), Nichelle Nichols (“Lt. Uhura”), Leonard Nimoy (“Mr. Spock”), Star Trek creator Gene Roddenberry, an unnamed NASA official, and Walter Koenig (“Ensign Pavel Chekov”).
Fifty years after Gene Roddenberry launched the Star Trek series on American television, many of the then-futuristic devices and ideas on the award-winning show have become commonplace on Earth.
Roddenberry’s creativity and extensive homework in consultation with scientists and engineers of his day infused the show with technology such as photodynamic therapy, laser weapons, and handheld sensors and communication devices. In the process, his sci-fi world colored our expectations, inspiring more than a few young people with a level of interest that led to STEM careers.
The short list that follows notes photonics-enabled ideas and props from the initial series (1966–69) that have become reality. See the January 2016 SPIE Professional magazine article for more.
1. The Replicator: today’s 3D printer
Star Trek’s replicator synthesized food, water, and other provisions on demand.
Today, the company 3D Systems sells consumers a popular 3D printer based on stereolithography, a solid-imaging technology for which company founder Chuck Hull received a patent in 1986. General Electric uses laser-powered 3D printers to create jet-engine fuel nozzles and other complex components
In space, a 3D printer from the company Made in Space was delivered to the International Space Station to test the effects of microgravity on 3D printing.
2. The Communicator: the first flip phone
Captain Kirk and other Enterprise crew members flipped open their personal communicators to speak to someone elsewhere on the starship or on a planet below.
Motorola engineer Martin Cooper, who invented the first mobile phone, told Time magazine that his invention was inspired by the Star Trek communicator.
The flip phone already has been succeeded by smartphones and tablets; photonics devices with displays, lenses, cameras, and more. Lasers are used to manufacture the processors, cases, and batteries and to mark a serial number on each device.
3. The Long-Range Scanner: today’s space-based sensors
Scanners on the Enterprise could detect atmospheric chemistry and presence of water on faraway planets, and even count life forms.
All of this is possible today via satellites or aircraft equipped with photonics sensors.
This year, the European Space Agency will launch a spacecraft equipped with sensors that optical engineers developed to search Mars for evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes, using two infrared and one ultraviolet spectrometer.
4. The Tricorder: tomorrow’s Tricorder!
The Star Trek tricorder (a TRI-function reCORDER) was a black rectangular device with a shoulder strap with three functions: to scan a person or unfamiliar area, record technical data, and analyze that data.
For today’s Tricorder, contestants for the $10 million Qualcomm Tricorder XPRIZE are competing in developing a consumer-friendly device capable of diagnosing 15 medical conditions and capturing metrics for health. Consumer testing of finalist teams’ solutions is scheduled for this September, with the winner to be announced in early 2017.
5. Invisibility Cloak: object cloaking
Metamaterials have been demonstrated to effectively cloak objects by manipulating the paths of lightwaves through a novel optical material, demonstrating the basic physics used to make Romulan and Klingon spacecraft invisible in Star Trek.
Sir John Pendry of Imperial College is one of the real-life pioneers of invisibility cloaking with negative-refractive-index metamaterials, and many others report on their research at various SPIE conferences on metamaterials and plasmonics.
6. Healing with light: photodynamic therapy
Star Trek’s chief medical officer, “Bones,” used light for surgery, wound care, accelerated bone healing, and as a dermal regenerator to rebuild skin -- all of which will be discussed at SPIE BiOS during SPIE Photonics West in San Francisco next month.
Lasers and specific wavelengths of light are used today to treat cancer and help skin heal faster, and for for aesthetic treatments, dentistry, and eye surgery. Transcranial near-infrared laser therapy (NILT) has been used to reduce the severity of stroke. Complex skin cancers have been treated at University of Lund and elsewhere using light-activated (photodynamic) medicine.
What fueled your dreams?
Theoretical physicist Stephen Hawking once wrote that "Science fiction such as Star Trek is not only good fun but it also serves a serious purpose, that of expanding the human imagination.” With a nod to such inspiration, the SPIE Photonics West 2016 welcome reception will celebrate the Star Trek anniversary.
What other light-based technologies depicted by Star Trek or elsewhere in science fiction serve a real purpose today or inspired your STEM career?
15 December 2015
|Researchers are learning more about how to improve cancer|
detection through teaching pigeons like the two above
to identify images of cancerous cells.
Researchers from the University of California Davis, the University of Iowa, and Emory University published a paper last month detailing how they trained pigeons -- Columba livia, commonly called rock doves, to be precise -- to detect cancerous cells. The birds attained an accuracy rate of 85%, higher than the accuracy of humans doing the task (84%), the Chicago Tribune reported. (Also see the Wall Street Journal for more coverage.)
And when four pigeons were tested on the image and their results combined (“flocksourcing”?), the birds were 99% accurate in identifying cancerous cells.
The researchers also found that while the pigeons had high-accuracy results when looking at slides from tissue samples, they were not able to learn how to accurately identify signs of cancer when looking at mammograms. Unlike biopsied cells viewed under magnification, mammogram images show neighboring tissues such as blood vessels, a factor which affects human accuracy as well.
Because a pigeon’s vision works much the same as a human’s, the research could help scientists improve the results in teaching humans how to visually identify cancer.
“Pathologists and radiologists spend years acquiring and refining their medically essential visual skills, so it is of considerable interest to understand how this process actually unfolds and what image features and properties are critical for accurate diagnostic performance,” the researchers wrote in their article in PLoS ONE.
The research team included Edward Wasserman, Stuit Professor of Experimental Psychology at the University of Iowa; Elizabeth Krupinksi, professor and Vice Chair for Research in the Department of Radiology and Imaging Sciences at Emory University; Richard Levenson, professor and Vice Chair for Strategic Technologies in the Department of Pathology and Laboratory Medicine at the University of California Davis Medical Center; and Victor Navarro, a graduate student in the Department of Psychological and Brain Sciences at the University of Iowa.