My Note: Recently, I reached out to Dr. Willie Padilla, at Boston College regarding the amazing work he is doing at BC relating to the development of metamaterials which can be employed in the terahertz regime. Dr. Padilla along with his research assistants, graduate students, Claire M. Watts, and David Shrekenhamer, recently announced that they had created a revolutionary single-pixel imaging technique which takes images that are guided through a coded aperture using a semiconductor to guide and direct the reproduced image of an object once THz waves have passed through it. The BC team described this technique as depicted in the picture above in the following way:
"A new method for single pixel terahertz (THz) imaging developed by Boston College researchers uses a set of instructions delivered by a laser beam to tune THz waves in order to produce new types of THz images. During the imaging method devised by the team, THz waves pass through an object (a); then they strike a silicon semiconductor (b) given specific instructions about how to sample the image; that data is passed along in order to digitally reconstruct an image (c) of the original object in just a few seconds. "( Image credit: Claire M. Watts, Boston College).
Here is what I wrote to Dr. Padilla, and his response, which Ms Watts,
Dear Dr. Padilla,
Thank you for agreeing to answer a few questions for me, and for readers of my blog, Terahertz Technology. As I know, I am a layman, and please excuse any of my questions which may be inartful, naïve or simply inane.
1. Are there names or other identifiers for the specific metamaterials which you have created for use in THz? If so, can you share that information, to give readers an idea of the number of different materials which you have developed for use with terahertz radiation?
Metamaterials can be scaled across almost the entire electromagnetic spectrum, from optical to microwave. What designates THz metamaterials is their size, the unit cell dimensions being on the order of tens of microns. Additionally, we choose to use materials that interact appropriately in the THz regime. There are many different metamaterials that have been designed to operate in THz, achieving many different electromagnetic responses. For example, we have developed perfect absorbers, polarization sensitive and insensitive metamaterials, multi-frequency metamaterials, and spatially patterned metamaterials. We and other researchers have also created dynamic reconfigurable metamaterials whose material response can be controlled through a variety of mechanisms including electronic, optical, thermal, and mechanical.
2. Do the metamaterials you have developed rely upon the use of either photons or electrons for the generation of THz? Perhaps asked another way, would a device created with the use of your metamaterials function in the realm of electronics or photonics, (both or neither)?
THz metamaterials are typically fashioned within the photonic domain having demonstrated the ability to tailor the electromagnetic response in ways that are difficult and or expensive to find within natural occurring materials.
3. How close or how far away (months or years) are you from developing commercially viable uses for your single pixel THz camera, enhanced by your coded aperture semiconductor?
There are a lot of aspects about our imaging system that make it reasonably close to a commercially viable THz camera. First, the masks are reconfigurable and easily changeable. This allows us to image many different types of scenes. Second, the optics are easily transferable to a lens system, just like the one we see in conventional cameras. Third, and most importantly, we use a very low power source which makes our device easily adaptable to real world use.
4. Are there any plans to spin-off your work into a private or publically held entity to further develop and market your work?
We have no plans to spin off this work into the private sector. We have, however, applied for various patents related to our technology.
5. Are you involved in any way with compressive sensing, (cs) and does your single pixel camera rely in any way upon cs?
We are currently working on a few projects using compressive sensing. This particular implementation of the single pixel camera does not rely on CS, but rather uses Hadamard masks to improve SNR over conventional raster scan masks. However, we are now investigating several new designs that utilize CS methods in a single pixel camera architecture, similar to the one we are using in this project. In these single pixel cameras, the time of image acquisition is directly tied to the number of measurements you take. Therefore, by using CS methods to reduce the number of images, we can greatly reduce the image acquisition time. In the next iteration of this project we plan to implement these methods to increase our image frame rate.
6. Are you in contact with or do you do you work with any of the current commercial ventures engaged in the sale of THz products, Advantest, Coherent, Teraview, Advanced Photonix, Agilent, Genia, etc.?
No.
I want to thank Dr. Padilla, and his team for taking time to answer these questions, relating to the amazing work they are doing. Cheers to them!
(for a related link see:
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