Though I listed some good Halloween reading a few days ago, I couldn't resist suggesting a few more! I'm sure most people will be heading to bed soon, so here's…
Optics basics: Inverse problems
In previous posts, I’ve talked at some length about computed tomography (CT) and optical coherence tomography (OCT). Each of these is a technique for determining information about the internal structure of an object, such as the human body, from exterior measurements of the scattering of electromagnetic waves from the object. In the case of CT, x-rays are used to measure and image a cross-sectional ‘slice’ of the human body, while in OCT, broadband visible light is used to probe a few millimeters into the skin or an internal organ of the human body.
Plenty of other techniques exist for measuring the internal structure of objects, using a variety of different types of waves. Magnetic resonance imaging (MRI) subjects a patient to an intense magnetic field, and makes an image by measuring the radio waves emitted when the field is suddenly switched. Ultrasound imaging uses ultrasonic waves to probe the soft tissues of the human body, and is used in mammography.
Each of these techniques is quite different in its range of application, but all require nontrivial mathematical techniques to reconstruct an image from the raw scattered wave data. These mathematical techniques are broadly grouped into a class of problems known as inverse problems, and I thought it would be worth an optics basics post to discuss inverse problems, their common features, and the challenges in solving them.
Aaaagh! Attack of the work-week!
Just a brief apology about the lack of science posts this week. Work has been crazy: on top of trying to catch up on all the class stuff I ignored…
Bertram Mitford’s The Sign of the Spider
It’s hard to find out information about author Bertram Mitford (1855-1914). Even Wikipedia doesn’t have information about him, instead redirecting to another Bertram Mitford who wrote about Japan. He was, like H. Rider Haggard, a writer of adventure stories set in the wilds of Africa, though certainly not as well known (Haggard wrote King Solomon’s Mines and She, the latter of which I’ve blogged about before). Valancourt Books, which has not led me wrong yet, has been valiantly reprinting much of Mitford’s work. I decided to give The Sign of the Spider (1896) a read:
I was, quite frankly, blown away. According to the book notes, Mitford has been dismissed as an imitator of Haggard. I found The Sign of the Spider to be a much more compelling, and even deep, read than any of the Haggard work I’ve read so far. A summary and some observations follow.
I voted! Early!
Well, it took 1 1/2 hours, but I got my early voting in! And I didn't get tricked by the abysmal design of the NC ballot. For me, the occasion…
Halloween Treats, 2008
It's time for my yearly installment of classic horror stories for some good Halloween chills! My 2007 edition can be found here. Happy reading, and Happy Halloween! The Dead Valley,…
Letchworth State Park: The panoramas
I mentioned in my post on Letchworth that I had a bunch of panorama photos to put together when I got home, and I’ve done so! They’re posted below…
John Wyndham’s The Day of the Triffids (1951)
This continues my brief foray into 1950s/1960s horror/science fiction, which I started with John W. Campbell’s Who Goes There?, which was the source for The Thing From Another World and John Carpenter’s The Thing. Today let’s talk triffids! A couple of weeks ago I finished reading John Wyndham’s classic apocalyptic novel, The Day of the Triffids (1951), and I thought I’d share some observations about it and how it relates to the science fiction film of the same name.
FiO: Day 4 and day 5
Well, I’m home! A hectic final few days at the FiO conference combined with a lack of hotel internet access prevented me from checking the blog very often (I would wander around the Hyatt, where I wasn’t staying, looking for a place where I could get a signal — and the optimal location always changed).
I attended fewer talks on the last couple of days, in large part because I switched into planning collaborative research projects. I attended a few special sessions, however: one on the 200 year anniversary of polarization, and one which encompassed the ‘best of topicals’. I briefly summarize these below.
FiO 2008: Day three
All the ‘big ticket’ events took place on the first and second days, so by day 3 I settled into listening to some shorter talks on various subjects. Also, day 3 is about the time I start trying to actually get some work done and start drifting away from sitting in sessions all day. I did manage to sit in on a number of talks on plasmonics and metamaterials, and I briefly summarize some of the substance below.