Pages- Terahertz Imaging & Detection

Friday, April 10, 2009

Some questions for Dr. Mittleman

First, thank you Dr. Mittleman for joining our small group, and for your posts. I honestly, believe that our group will grow, and you could greatly assist in that process, by sharing some of your cutting edge knowledge with us. Obviously, if you decline to comment on any particular topic, I fully respect your decision. Secondly, please excuse any obvious technical gaffe in the questions I ask. Dave in Ohio, who is a group member, has an engineering/optical background so perhaps he will ask better questions.
So, here goes.First, and foremost, what do you see as the greatest impediment to commercial acceptance of the current Teraherz machines on the market, and do you envision any breakthroughs in the near future in pharma, oil & gas, or other, in the near future?Second, as between the various terahertz applications, machines on the market, (eg. Thru-vision, passive, Api, & Teraview, time-domain) do you envision any significant technological breakthoughs for any of the commercial, "players", and how would you rate each application today? You have indicated that Thz is an unlikely candidate for medical imaging similiar to xray? I got this faulty understanding from web pages such as wikipedia, where the following is found:
http://en.wikipedia.org/wiki/Terahertz_radiation
"Theoretical and technological uses under developmentMedical imaging: Terahertz radiation is non-ionizing, and thus is not expected to damage tissues and DNA, unlike X-rays. Some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content (e.g. fatty tissue) and reflect back. Terahertz radiation can also detect differences in water content and density of a tissue. Such methods could allow effective detection of epithelial cancer with a safer and less invasive or painful system using imaging. Some frequencies of terahertz radiation can be used for 3D imaging of teeth and may be more accurate and safer than conventional X-ray imaging in dentistry. Security: Terahertz radiation can penetrate fabrics and plastics, so it can be used in surveillance, such as security screening, to uncover concealed weapons on a person, remotely. This is of particular interest because many materials of interest have unique spectral "fingerprints" in the terahertz range. This offers the possibility to combine spectral identification with imaging. Passive detection of Terahertz signatures avoid the bodily privacy concerns of other detection by being targeted to a very specific range of materials and objects. [3] Scientific use and imaging: Spectroscopy in terahertz radiation could provide novel information in chemistry and biochemistry. Recently developed methods of THz time-domain spectroscopy (THz TDS) and THz tomography have been shown to be able to perform measurements on, and obtain images of, samples which are opaque in the visible and near-infrared regions of the spectrum. The utility of THz-TDS is limited when the sample is very thin, or has a low absorbance, since it is very difficult to distinguish changes in the THz pulse caused by the sample from those caused by long term fluctuations in the driving laser source or experiment. However, THz-TDS produces radiation that is both coherent and broadband, so such images can contain far more information than a conventional image formed with a single-frequency source. A primary use of submillimeter waves in physics is the study of condensed matter in high magnetic fields, since at high fields (over about 15 teslas), the Larmor frequencies are in the submillimeter band. This work is performed at many high-magnetic field laboratories around the world. Submillimetre astronomy. Terahertz radiation could let art historians see murals hidden beneath coats of plaster or paint in centuries-old building, without harming the artwork.[4] Communication: Potential uses exist in high-altitude telecommunications, above altitudes where water vapor causes signal absorption: aircraft to satellite, or satellite to satellite. Manufacturing: Many possible uses of terahertz sensing and imaging are proposed in manufacturing, quality control, and process monitoring. These generally exploit the traits of plastics and cardboard being transparent to terahertz radiation, making it possible to inspect packaged goods. "
Care to give us any thoughts on what is and isn't accurate in the above description?
Once again, comment when you have the time and desire, but there are a number of people visiting this group and blog, even if they haven't joined or commented yet. Thanks!

1 comment:

  1. Dr. Mittleman responds on the companion group discussion page.

    "Randy,
    I'll try to answer your questions as best I can. Let me start by saying
    that I am truly a "teravangelist" - that is, I believe quite strongly in
    the potential value of this technology. Having said that, I also recognize
    that there is a lot of hype and inaccuracy out there, and it is important
    to distinguish this nonsense from the real promise. The wikipedia article
    is a good case in point - it contains some statements that are true, some
    that are true but incomplete, and others that are just overselling the
    technology.



    > First, and foremost, what do you see as the greatest impediment to
    > commercial acceptance of the current Teraherz machines on the market,
    > and do you envision any breakthroughs in the near future in pharma,
    > oil & gas, or other, in the near future?


    I think the field of THz technology is very much in a chicken-and-egg
    situation: many people are reluctant to think seriously about real-world
    applications when the technology is as expensive as it is, but real-world
    applications are what will eventually drive down the per-unit cost of
    instruments. This problem has been around for some time, but is gradually
    being overcome by a variety of factors (growing recognition of the
    potential in various areas, increased federal research funding, etc.).
    Ultimately, I think there will be some really important applications that
    will drive the subsequent development. I can't say what market segment is
    the most promising - there are too many variables there. I do suspect that
    there are possible applications that nobody has yet considered. Remember,
    most people still have never heard of "terahertz".


    > Second, as between the various terahertz applications, machines on the
    > market, (eg. Thru-vision, passive, Api, & Teraview, time-domain) do
    > you envision any significant technological breakthoughs for any of the
    > commercial, "players", and how would you rate each application today?


    ooh my, if I could answer this question, then I'd be pursuing those
    breakthroughs, not just talking about them. I'm quite certain that the
    field has a long way to go, which implies that there will be important
    technological advances, possibly revolutionary ones. But forecasting those
    is impossible - that's the nature of basic research. As to rating specific
    applications, that's really difficult too. For example, you have mentioned
    medical diagnostics as an interesting area. I agree, it is interesting.
    But the feasibility has yet to be proved, and my sense is that the
    scientific community is growing skeptical, since the idea has been around
    for quite a while and has yet to gain significant traction. Ultimately, I
    would expect a few niche applications in biomedical areas. Those niche
    applications could end up being quite significant in terms of raising the
    profile of the technology, or they could have almost no impact at all.
    It's just too early to say. In the area of medical diagnostics, the basic
    scientific questions have not yet been answered with sufficient clarity to
    provide a good forecast.

    Anyway, I hope that helps you understand the situation a bit better.
    Thanks for making the effort to spread the word about T-rays!


    Regards,
    Dan

    ReplyDelete

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