“Oh what a tangled web we weave, when first we practise to deceive” ~ Sir Walter Scott.

Monday, June 16, 2008

Sph-Eric Aberration

fter many attempts to create a carefully-worded email to send to "Doug" were scrapped before sending, I settled down to write in advance of the beginning of the academic term of fall 2006. I was aware that Doug would be leaving the East Coast at about this time in order to relocate to the West Coast permanently to take up a research fellowship position in California. While I knew that I did not have the luxury of an extended period of time to make contact, I wished to ensure that my email would encourage some sort of response that would help me and I wanted to address the suggestion he'd made in an earlier email that I might have confused him for someone else.

The thought that he could think me so foolish was unsettling, to be sure. I'd never jump to a conclusion without checking facts closely before communicating that I'd discovered his real identity. In my typical fashion, rather than be annoyed, I concluded that this was his way of implying that I was suffering from Sph-eric aberration. No way, indeed! Well, not on my part anyway.

The dictionary defines aberration as a deviation from its proper or expected course; a defect or blurring of focus; an imperfect image caused by a physical defect in an optical element, as in a lens, or an abnormal alteration of one's mental state.

Spheric aberration (SA) is image imperfection that results from a lens that is spherical in shape. Without getting too technical, light rays which are parallel to the optic axis but at different distances from the optic axis, fail to converge to the same point. This creates an aberration and the defect that is most noticeable for light striking the outer edges of the source. The result is that the images of objects are often blurry and unclear.

Of course spheric aberration can be reduced or eliminated by alteration in the shape of the lens or mirror, as well. For example, a parabolic lens or mirror will bring all reflected rays into a common focus. However, when a small screen is placed at the paraxial focal plane and then moved toward the mirror or lens, a point is reached where the image size is focused to a minimum. The precise location of this point is termed the "circle of least confusion" and that is precisely the reason for contacting him ...to approach a point of least confusion.

I carefully composed an email that simply projected friendly contact. No mention of anything unpleasant, and I inserted a joke that would be especially pertinent, given that I was now absolutely certain that he was of Canadian origin. I hoped that this benign and friendly correspondence would be received in the spirit in which it was offered and would reopen the line of mutual contact.