Oct 03

Photonics for Global Health

By JamesVanHowe CLEO Conference, CLEO Tech Transfer, CLEO: Applications No Comments »

Left: Reflection images of a histopathology slide corresponding to skin tissue using a low-cost, portable, lens-free off-axis holographic microscope. Right: Conventional reflection-mode microscope image of the same specimen using a 4X objective lens (NA: 0.1). Image from Biomedical Optics Express.

This post originally appeared on Jim’s CLEO Blog and is reproduced with permission from the author.

Research performed in the Ozcan group at UCLA holds a unique place in the field of optics and photonics. Besides the typical pursuit of advancing optical technology, another major initiative of this photonics group is solving problems of global world health, particularly in resource-poor countries.

Early September marked a milestone for the UCLA group as they published work on a compact, low-cost (~$100 USD of parts), dual-mode microscope with 2 micron resolution in Biomedical Optics Express (also written up in a recent OSA press release). The key to making such a low-footprint, low-cost, lab-grade device is using holographic microscopy. The image information stored in a hologram (the interference of the reflected or transmitted light from the specimen with a reference beam) requires no lenses, drastically reducing the weight, size, and overall expense of the device. A computer reconstructs the wavefront reflecting from (or transmitting through) the sample instead of a lens (see fig below). The impact to world health will be increased blood-diagnostics, water quality tests, tissue screening and analysis, and other imaging diagnostics in areas where microscopes currently are not available due to cost and/or remoteness of location. Getting more microscopes into the hands of health workers may have large impacts for heading off disease outbreaks as well as treatments for individuals.

The idea of using holograms in microscopy is not new. In fact it was the quest for higher resolution in electron microscopy which prompted Dennis Gabor to devise wavefront reconstruction by holography in 1948. Gabor coined the word “hologram” which translates “whole message” to emphasize the amount of information that is stored in this very special interference pattern. For a brief history of holography from its roots in microscopy, its development through radar, and its boom in mainstream art and media in the 60′s and 70′s , see Jeff Hecht’s 2010 OPN article.

Schematic of the 200 gram microscope developed by the Ozcan group in reflection mode. LD: laser diode, PH: pin hole, BC: Beamsplitting Cube. Note the two AA batteries as the power source as well as for scale. Image from M. Lee, O. Yaglidere, and A. Ozcan, Biomedical Optics Express, 2, 2721 (2011).

What makes the Ozcan group’s work so special is not the use of a fundamentally new technique, but clever and impressive engineering. This holographic microscope is small, inexpensive, and can work in both transmission and reflection mode. The transmission mode of the current device is similar to an earlier work by the Ozcan group- a cell-phone microscope. In the summer of 2010, the UCLA group published work in Lab on a Chip demonstrating a clever attachment to an ordinary cell-phone which could convert it into lab-grade microscope (see the youtube short below). By employing digital holographic microscopy, the group was able to produce a 38 gram attachment without any lenses, lasers, or bulky optics, which when incorporated with the cell phone camera, produced hologram on the cell phone detector array. The idea is that the hologram data would be sent over the same cell phone to the closest hospital/analysis station, a computer would process the hologram to extract the image information, and then the image would be sent back to the same phone, all within seconds of placing the sample to be analyzed into the device.

Though the current device cannot be so easily integrated onto a phone, the additional benefit of reflection-mode operation makes up for its “bulkiness.” By operating in reflection-mode, the new microscope is additionally suited for imaging optically dense media like tissue, something not possible using in-line transmission holography due to spatial distortions in the reference wave…  To read the full original post, click here.

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May 04

When light dances with sound, teases the molecules, and plays an important role in green energy!

By Frank Kuo CLEO Conference, CLEO Tech Transfer, CLEO: Expo, QELS Conference 2 Comments »

This post originally appeared on CLEO 2011 by Frank Kuo and is reproduced with permission from its author.

Shuffling among many eye-opening technical sessions and CLEO’s Market Focus & Technology Transfer Showcase, I simply realize adventures with light are everywhere:

An amazing imaging technique called photoacoustic imaging/microscopy (JTuG) caught my full attention on Tuesday. It is a perfect example of light collaborating with sound to achieve something fascinating.  Think about it, light and sound are siblings. They are governed by similar natural laws. You might argue that light can propagate in vacuum while the sound needs media to do so. But again, they are siblings, not twins. So this argument does not really hold. Anyway, taking that into account, isn’t it fun to see them hold hands and work on something new together!?

The principle behind this new imaging technique is actually straightforward. The pulsed laser light (MHz repetition rates) is focused into the tissue; the tissue of interest absorbs the light and expands. This process is repeated with laser repetition rate. The pulsed expansion creates the ultrasonic sound wave, and we detect this by transducers. We then reconstruct the image of the tissue through some complex algorithm. We know that ultrasonic can penetrate deep tissue, while the resolution of ultrasonic is not as great as optical imaging. On the other hand, optical imaging can only go to a few millimeters deep. By endeavors of the researchers in improving this technique, photoacoustic imaging actually combines the strength of these two – it can do deep tissue imaging with optical imaging resolution – optical resolution photoacoustic microscopy.

An experimental layout for photoacoustic microscopy.

Continue reading »

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Nov 24

Emerging THz technology could solve body-scanner controversy

By JamesVanHowe CLEO Conference, CLEO Tech Transfer, CLEO: Applications No Comments »

From TeraView press release Jan. 2010, THz Spectra of explosives (threats) and different clothing materials (non-threats).

This post originally appeared on Jim’s Cleo Blog and is reproduced with permission from its author.

Today, the day before Thanksgiving, is one of the busiest holidays for air-travel in the U.S. The latest hubbub in U.S. airport security is the use of x-ray body scanners to detect for potential explosives or weapons carried by passengers. The scanners spray the traveler with soft x-rays and then detect the back-scattered radiation to produce an image of the passenger, minus his or her clothing. Many travelers have found this new level of security too invasive and have opted out for the traditional pat-down. Others have used their experience as the “butt” of jokes; Humorist Dave Barry recently described his ordeal of going through airport security of having both the scan and a pat-down due to a “blurry groin area” from the image. The threat of body-scanner boycotts from various websites and blogs prompted transportation security administration (TSA) chief John Pistole to plead to holiday-travelers to put security needs above personal modesty since the pat-down takes much longer and will lead to travel delays, inconvenience, and economic hardship for the travel industry.

The first thing that came to my mind in the flurry of stories I’ve been hearing regarding body-scanners and privacy issues was Terahertz (THz) radiation. What makes THz radiation useful for a body-scan is that it is readily transmitted through non-metallic and non-polar materials like clothing. However, there is more to THz imaging than just seeing through clothing which could make THz scanners both a more effective and less invasive tool than x-ray scanners.

Unlike x-rays, there are a number of explosive, chemical, and biological agents of interest for threat-detection that have characteristic THz spectra, including PETN which was found in the “underwear bomber’s” briefs after his foiled attempt to blow-up a plane near Detroit last Christmas. Rather than build up an image of the body and rely on the scanner operator to judge the potential threat from visual inspection, a THz scanner could look at the reflected spectra point-by-point to compile a molecular fingerprint by comparing to a database of absorbance spectra. Effectively, this technique is “THz spectroscopy through clothing”. You build up a chemical map across the body instead of a body image. TeraView of Cambridge announced work on such a scanner last January when the U.K. ran into similar passenger discontent over x-ray body-scans. Besides giving travelers back their modesty, this technique likely could give better threat detection as well as less false-positives since threats are identified chemically instead of visually.

To find the latest breakthroughs on THz scanners, be sure to attend sessions under CLEO: Science & Innovation: Terahertz Technologies and Applications, or CLEO: Applications & Technology: Government & National Science, Security & Standards Applications this May. Until then, have happy, safe, and hopefully noninvasive travels……for the full original post, click here.

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Nov 01

Your mother may think you’re special, but does CLEO?

By JamesVanHowe CLEO Conference, CLEO Tech Transfer, CLEO: Applications, QELS Conference No Comments »

Reproduced from Ref. 1. Magnetomotion OCT (MM-OCT) of chiken breast tissue.

This post originally appeared on Jim’s Cleo Blog and is reproduced with permission from its author.

CLEO conference organizers recently posted the categories for the Special Symposia which are to include five areas: 1) Nano-bio-photonics, 2) Broadband Spectroscopy: New Techniques and Sources, 3) Quantum Communications, 4) Fiber Parametric Devices and Applications, and 5) Light-emitting Nano-plasmonic Devices.

Among other invited speakers in the Nano-bio-photonics Symposium, Stephen Boppart from University of Illinois, Urbana-Champaign, will be discussing “Endogenous Molecules or Exogenous Molecularly Targeted Contrast Agents for OCT.” OCT, or Optical Coherence Tomography, was pioneered in the early 1990′s by James Fujimoto of MIT, who will also be giving an invited talk in this Symposium. OCT uses the cleverness of interfering low-coherence light to scan through tissue to depths up to a few millimeters and with an axial resolution equivalent to the coherence length of the source, typically less than 10 microns. Complete OCT setups can be purchased commercially, like Thorlab’s OCS1300SS. In fact, during my last eye-checkup I asked my optometrist if she had heard of OCT since they are becoming more widely used by opthamologists to probe retinal health and conditions. She did. In fact, she had participated in a clinic to understand how to use OCT and read images.

Though roubst, OCT has been limited to a small number of medical applications because it is insensitive to standard molecular probes used by biomedical researchers such as fluorophores or bioluminescent markers. This is because fluorescence and bioluminescence arise from inelastically scattered light, and OCT is sensitive only to elastically scattered light (light coherent with the source). Therefore, in order to use molecular probes with OCT to diagnose a wider variety of diseases or to answer fundamental questions of cellular function, one must use a different set of probes that are sensitive to elastic scattering properties of light like changes in scattering itself, absorption, polarization, phase, or frequency.1

From the title of the talk, I imagine that Professor Boppart will be discussing some of the exogenous probes (probes introduced into the tissue) he and his group have created and used for OCT like metallic nanoshells and microspheres engineered from a variety of materials to enhance scattering.1 My favorite of the ingenuous probes are particles with high magnetic susceptibilities such that when modulated with a magnetic field, their subsequent motion changes the local scattering properties of the tissue, see the figure above.1 I also suspect he will be talking about endogenous probes (where the tissue of interest naturally contains helpful probes) like collagen that can be stimulated by a coherent process like second harmonic generation, or Hb/HbO2 whose scattering and absorbing properties are frequency-dependent.1 I’m excited to hear advances in this work as well as attend the other symposia.

The latter four symposia are open for submission of contributed papers and you can find the CLEO or QELS subcategory to which to submit beneath the particular symposium description. I’m particularly interested in the Broadband Spectroscopy Symposium since one of the emphases is Mid IR sources, a new interest of mine. I also am excited that the Quantum Communication Symposium, which like the Nano-bio-photonic Symposium, has been placed under the designations of QELS: Fundamental Science, and CLEO: Science and Innovation, and CLEO: Applications and Technology. These symposia will attempt to show their fields from the idea-stage all the way to commercialization.

So if you think you’re special (which if you’re planning on submitting work to CLEO you most certainly are), take a moment to see if your work falls into the Special Symposia categories.

References

1. S. A. Boppart et al., “Optical probes and techniques for molecular contrast enhancement in coherence imaging ,” Journal of Biomedical Optics, 10, 041208, (2005).

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Sep 30

Call for Papers and CLEO’s New Direction

By JamesVanHowe CLEO Conference, CLEO Tech Transfer, CLEO: Applications, CLEO: Expo, QELS Conference No Comments »

This post originally appeared on Jim’s Cleo Blog and is reproduced with permission from its author.

As the leaves are changing color and the days are becoming shorter, it’s time to get your CLEO submission into shape. Time to order those parts with long lead-times. Time to optimize your code. Time to hunker-down, build your experiment and collect data. And this time, perhaps even demonstrate your prototype.

This Thursday marks the official Call for Papers for CLEO 2011 in Baltimore. The deadline for submissions (with the exception of post-deadline papers) is December 2, 12:00 pm EST. For your convenience, and hopefully not to stress you out, I’ve embedded a countdown timer at the top of the blog.

CLEO 2011 will prove to be even more exciting this coming May due to the addition of a new conference, CLEO: Applications and Technology. The classic CLEO conference, CLEO: Science and Innovation and CLEO/QELS: Fundamental Science, will still remain intact. The new conference will “explore the intersection of academic research with product commercialization.” Papers submitted to the Applications and Technology conference will demonstrate the transition of fundamental and applied research toward product commercialization. The conference programmers emphasize work should be pre-commercial. Topic categories include Biomedical, Environment/Energy, Government and National Science, Security and Standards Applications, and Industrial.

The addition of CLEO: Applications and Technology, to classic CLEO, QELS, Market Focus, and the Expo gives continuity to the spectrum (no pun intended) of innovation at the conference. Under one roof conference-goers will now be able to learn about break-throughs in fundamental science (QELS), applied science (CLEO), the transition of applied research to commercial products (Applications and Technology), commercial developments and research ready-for-commercialization (Market Focus), as well as see and purchase commercial products first-hand (Expo).

In my opinion, the move to foster more collaboration and communication between fundamental research and product development is wholly positive. I recently showed my electronics class the NOVA special Transistorized which recounts the development of the transistor. The history of this device that revolutionized all of our lives shows how synergy between commercial enterprise and fundamental science can produce both Nobel laureates and corporate behemoths like Sony and Intel. Let’s hope history repeats itself in Baltimore.

For the full original post click here.

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May 21

Exhibit and Power Lunch

By KseniaDolgaleva CLEO Conference, CLEO Tech Transfer, CLEO: Applications, CLEO: Expo No Comments »

A good thing about the exhibit is that you don’t have to submit and wait for a quote. It is simply enough to speak to a company representative to get an approximate idea about the prices, or sometimes even exact value. Walking around the exhibit, I’ve managed to get some things done, such as looking up an upgrade to our Coherent OPO and figuring out the pricing for certain items that I meant to check long time ago, always saving it for later. So, I’ve done my equipment homework. … (May 20, 2010) Click here to read the complete post.

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May 18

Celebrating laser’s 50th anniversary

By KseniaDolgaleva CLEO Conference, CLEO Tech Transfer, QELS Conference No Comments »

I’ve been looking forward to the 50th Anniversary of Laser symposium. Like many of you, I am sure. It was surprising how many people succeeded to arrive that early to attend this remarkable event. I almost felt spoiled having so many distinguished scientists in one session. The memories in their presentations were flashing at us with the old scanned photographs, original hand-written equations and raw data collected with the first laser, together with the well-known pictures and graphs from the old articles that we have seen used in the Lasers textbooks. It truly makes you feel like you are in the middle of some significant experiment, at the edge of the great discovery – the Laser. … (May 17, 2010) click here to read the complete post

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May 16

What’s Hot from the U of Toronto

By KseniaDolgaleva CLEO Conference, CLEO Tech Transfer, CLEO: Applications, QELS Conference No Comments »

Before the conference started, let me overview some upcoming interesting talks that I already know something about. These are presentations by the Photonics Group at the University of Toronto. I am sure that CLEO/QELS attendees will find quality research and exciting new results there, so I would like to give you all some heads-up. … (May 16, 2010) Click here to read the complete post

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May 15

Optics on a microchip

By KseniaDolgaleva CLEO Conference, CLEO Tech Transfer, CLEO: Applications No Comments »

Photonics group at the ECE Department at the University of Toronto has been working to enable practical realization of all-optical devices for telecommunications, lab-on-a-chip, sensors, and many other applications. We are happy to have the Emerging Communication Technologies Institute at the University of Toronto that provides us an access to the state-of-the-art electron beam lithography apparatus and microfabrication clean room facilities. Equipped with these advanced tools, so important for successful research in integrated optics, we collaborate with each other to accelerate the progress in the field. … (May 15, 2010) click here to read the complete post

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May 05

Quantum sources: Are diamonds your best friend?

By David Nugent CLEO Conference, CLEO Tech Transfer, CLEO: Applications, QELS Conference No Comments »

Enticed perhaps by successes with laboratory quantum key distribution demonstrations, academic and commercial interest in single photon sources (SPS) has accelerated in recent years. To celebrate the 50 year anniversary of the invention of the laser, I wrote an Innovation Brief on single photon sources and you can download a copy here.

Photo credit: Swamibu

Broadly speaking single-photon generators can be broken down into three categories:

  1. Nitrogen vacancies (‘NV’) in high-purity diamond.
  2. Single quantum dots (‘QDs’) encapsulated in nanostructures.
  3. Other methods such as spontaneous parametric downconversion.

CLEO/QELS 2010 does not disappoint with papers covering all three SPS topics, though admittedly the program is focused on NV and QD sources. Here is a selection of my own pick of the crop.

Quantum Emitter Photonic Devices

Monday, May 17, 3.45pm – 5.30pm

Presider: Won Park, Univ. of Colorado.

Stephan Reitzenstein (Univ. Wurzburg) et al will present work on high-efficient electrically driven quantum dot micropillar SPSs. The authors report a record high (34%) coupling efficiency and single photon emission rate of 35 MHz under pulsed electrical excitation. I will be interested to learn about the operating temperature of this configuration and the manufacturability of the micropillar structures.

Birgit Hausmann (Harvard Univ.) et al will present work on a hybrid diamond-plasmon particle device containing individual NV centers for QIP and quantum cryptography applications. My personal view is that plasmon enhancement could play a crucial role in the realisation of practical single-photon sources, so this talk is particularly interesting for me.

Finally, Matthew Rakher (NIST) et al will discuss progress on fiber-coupled waveguides for enhanced resonant interactions with single QD sources. I wonder method of fiber coupling Rakher will present. Photonic crystal fibers, I guess?

QELS Symposium on Quantum Repeaters and Networks (QWD)

Wednesday, May 19, 1.30pm to 3.15pm

Presider: Christoph Simon (Univ. of Calgary)

Continuing the theme started by Rakher et al the day before, Paul Barclay (Hewlett Packard) et al will present work on optical coupling between NV centers in single-crystal diamond and hybrid gallium phosphide microcavities.

Poster Session

Wednesday, May 19

Although I have read many papers on the embedding of NV centers into nanostructures to achieve Purcell effect efficiency enhancements, I have never heard about embedding a single-photon crystal source inside or atop a host crystal. A poster by Luke Stewart (Macquarie Univ.) et al show how the lifetime of NV emitters can be increased by incorporating nano-diamonds inside opals and the lifetime variance may be reduced by placing them on the surface of opals.

Australia boasts some great credentials in the development and exploitation of SPS science and applications, including the renown R&D labs at Quantum Communications Victoria. Will anyone from QCV will be attending CLEO/QELS this year? It would be great to hook up with them.

QELS: Single Emitters and Photons

Thursday, May 20, 4:45 p.m.–6:30 p.m.

Presider: Charles Santori (Hewlett-Packard Labs)

This session contains two papers discussing the post-production treatment of diamond-embedded NV centers. Santori himself will present a method for converting neutral NV centers to the desired negatively charged state, while Russell Barbour (Univ. of Oregon) will discuss the role of deformed silica microspheres in enhancing evanescent coupling between whispering gallery modes and neighboring NV centres embedded in diamond nanopillars.

What are your views on NV versus QD single photon sources? What are the biggest hurdles confronting each method? Drop us a note. Let’s debate!

Dr David Nugent is Founder and CEO of Elucidare Limited, a boutique technology development and investment advisory business.

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