Line Scanning: A Technical Appendix to Postblogging Technology, November 1955

 My familiarity with all of this begins with vignettes in Charles Stross novels in which Concordes and the like demonstrate that there's something to high Elizabethan British aviation technology by penetrating American air defences. Since sourcing pastiche science fiction novels is no basis for a system of historiography, I remained agnostic until I arrived at OPERATION SAGE BRUSH, which I find pretty fully summarised online here with respect to land operations,  and with respect to air superiority operations by Not A Pound For Air to Ground at Youtube.

SAGE BRUSH opened with 9 Aggressor B-57s crossing the Exercise's "Truce Zone." The Canberras of the attacking force easily evading defending interceptors and nuked 18 air bases as far north as Tennessee. Our narrator summarises the lesson of the Exercise as the one about the bomber always getting through and goes on to talk about the upcoming generation of American fighter bombers, blaming the Great Mistake of the Vietnam War on an excessive emphasis on atomic warfare (275 simulated atomic bombs with 15 simulated megatons was used by Aggressor forces alone in an exercise area consisting basically of Louisiana, a rather smaller area than, say, West Germany). This being a judicious combination of strategic velleities and hobby horses, I will defer to Newsweek, which focussed on the transient technological aspects, successful jamming and the unstoppable speed of the B-57. I mean, general atomic war is a bad thing, but they actually built F-111s and Buccaneers, and tried to build TSR-2s, so in some sense this part is more important. No-one, apparently, gives a shit about backward-wave oscillator, aka the "carcinotron," for reasons unknown to the author

As the electrons travel down the tube, they interact with the RF signal. The electrons are attracted to areas with maximum positive bias and repelled from negative areas. This causes the electrons to bunch up as they are repelled or attracted along the length of the tube, a process known as velocity modulation. This process makes the electron beam take on the same general structure as the original signal; the density of the electrons in the beam matches the relative amplitude of the RF signal in the induction system. The electron current is a function of the details of the gun, and is generally orders of magnitude more powerful than the input RF signal. The result is a signal in the electron beam that is an amplified version of the original RF signal.

Just kidding. Let's talk about Latin grammar next! But Concordes dropping James Bond pastiches on Cthulhu-occupied Washington (spoilers I guess) is a bit more graspable than analogue electronic circuits. Just one aspect of all this is tactical reconnaissance to find atom bomb targets, which you don't want to waste, there being only 300 of them to spare. (On the bright side, the defending side in SAGE BRUSH had twenty-five bombs to spare  for not-Louisiana at the end of the exercise.) The line is very pithy: The TSR-2 was to carry sidescanning "line scan" optics, which previously had gone into a pod on the Buccaneer. So what was that thing they did with the lines and the scanning?

By Halfblue - from en.wikipedia.org (http://en.wikipedia.org/wiki/File:
Maksutov_150mm.jpg), CC BY-SA 3.0, https://commons.
wikimedia.org/w/index.php?curid=10378575

It turns out that this is also the "read the headlines in Pravda over the shoulder of the guy sitting on a bench in Red Square" cameras," which is way cooler than Buccaneers crawling into the sky on their Gyrons and taking pictures of Commie stuff from safely offshore in the Baltic with their camera pods Truly, military surveillance is omnipresent and infallible, and let's not even talk about "bucket recovery,"  or the fact that space monkeys were apparently cover for developing this "technology." You can tell its cooler because the section on camera technology in the "Corona" article is (a lot) longer than the article about Line-scan cameras. The concept is just a narrow strip image because the best focusing lenses only produce an undistorted image at the centre, so if you rotate the camera while dragging it along, you produce a "scan" of up-and-down-in-a-track. Just five engineers were responsible for designing CORONA's optics, which were built at Hiller Helicopter's Palo Alto plant, and was just a part of the overall $108 million WS-117LO program (for fiscal 1958), so they were not developing a radical new technology here, but rather adapting lenses already in production for high-end cameras. No-one is particularly interested in those, either, but the big thing in the Fifties, and which do seem to meet the gnomic descriptions in the public literature, was catadioptric systems. Bernard Schmidt published a design in 1931 that was taken up in numerous telescopes of the Thirties, not an era that you associate with big spending on high tech, so I guess it's not surprising that everyone and his dog, Spot, began working on them as soon as wartime money flowed, including Dennis Gabor, who is prominent on account of doing it at Cambridge and then for the RAF, although probably more famous for getting the Nobel for Physics in 1971 for inventing holography. The rest of the Wiki goes all camera nerd, so you can get a sense of how many commercial camera builders were working with catadioptrics in the last pre-digital age. 

Wikipedia adds a Sixties vibe. More precise dating would
help, too.

Another bizarre (from the perspective of 2026) requirement of the camera package was the illuminants. With either flare dispensers or rockets incorporated, one stops to wonder about infrared photography. Wasn't that a thing? It turns out that it was not, due to the comparative insensitivity of available chemical fixatives to the infrared spectrum, and that all the infrared photography that we see before "the 1960s" is stunt photography. It appears that better developing processes first emerged during WWII and, if they were offered commercially in the "1960s," were available to military users by at least that date. So I have no idea what is up with the flares. I'll at least say this: The above link to Kodak promotional material at least helps me understand that "film" is not just film. Ektachrome infrared camera film was a five-layer acetate laminate of blue sensitive, yellow filter, green-sensitive, and red-sensitive strip on a backing layer, and the developing process uses nine separate chemical rinses and baths to produce a final image. So it's a bit hard to imagine all of that happening at a forward operational base, and that might be why the technology was not finding operational military applications but might have been used in strategic photographic reconnaissance. It'll do as a hypothesis, anyway.