In 1948, a phantasmal killer stalked Americans: thousands of motorists were dying on roads from what The New York Times described as “death rays”. Overcome by a blinding light – a “death dazzle” – they piled into oncoming traffic and telephone poles. But these death rays were not the stuff of fiction: they were headlights. As early as 1920, federal officials had declared the blinding glare of car headlights the country’s “chief road peril”. A peril, that was, to everyone except those driving a handful of cars in New York City. Owned by Edwin Land, the founder of Polaroid, these cars were mysteriously impervious to the rays. Had Land solved the greatest road safety puzzle of his time?
THE problem, Edwin Land concluded, always came down to one thing: “For safe night driving, each driver needs to put a powerful beam right where it will blind the other.”
Headlights were a mixed blessing to drivers. In their early years, they were flammable oil or acetylene lamps that occasionally incinerated the car. With no street lighting and no shoulders on the roads, cars in the US carried a pair of blazing headlights up front and often a third “ditch light” mounted on the right wing. On the narrow two-lane roads of the day, the effect was predictable: oncoming drivers blinded and killed both each other and pedestrians.
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A change to electric lights meant fewer car fires, but no less glare. Proposed solutions proliferated. “Mr Automobilist! Shade Your Headlights,” shouted an advert for Wridgway No-Glare Shade in 1909, while the Osgood Deflector Lens promised to “Light the Ground, Not the Air” and the Blindless Headlight Company pledged to “eliminate glare” altogether. Some claimed yellow headlights cut glare, while still others advised smearing grease or paint over the top half of the lens.
Nothing quite worked. Testing an endless flood of advice and gizmos, American road investigators found they produced little benefit. Fads such as coloured spectacles or swing-down perforated-tin visors reduced both glare and useful light so much that drivers were in graver danger than before. High and low beam systems helped but, as any driver knows, they rely on the undependable thoughtfulness of others.
Starting in New York in 1905, laws were introduced to regulate the brightness and height of headlights, but they were rarely enforced. Even when headlights were carefully shaded and adjusted to focus downwards, road vibrations nudged the beam upwards and into the eyes of other drivers. Regulators found that more than half the cars on the road had badly aimed headlights. Even a properly aimed light only worked when the car was travelling on a level road: cars driving up even the gentlest hills still faced the glare of oncoming traffic.
As car ownership and distances travelled soared, the human toll inexorably mounted: the “death ray”, it seemed, was unstoppable.
Enter Edwin Land. A Harvard dropout with vague notions of writing the great American novel, Land moved to New York in 1927 and settled on a different project altogether – conquering glare. The idea had preoccupied him since he was a teenager at summer camp, where he had watched a teacher demonstrate how a polarising crystal took the glare off a table top. During a night-time drive with one of the camp’s counsellors, he had a vivid demonstration of another kind of glare: they were nearly run off the road by oncoming traffic. Walking up Fifth Avenue years later, the two experiences clicked: why not polarise headlights and windscreens?
A polarising filter “combs” incoming light so that only waves moving in one particular plane pass through. Two polarising filters held at right angles to each other, so that the combing grids form a mesh, produce a striking effect: darkness. The trick, then, was to put a polarising filter over the headlight and a second filter over the windscreen, each oriented at the same 45-degree angle to the road. For drivers, the road ahead would remain visible, if somewhat dimmed, through their windscreen filter. But an oncoming car’s polarised headlights, shining directly into the cross-polarised windscreen, would hit at a combined angle of 90 degrees and be reduced to a faintly glowing pair of discs.
Land was not the first to have this notion. Lewis Chubb, director of research at Westinghouse Electric, applied for a patent on a polarising windscreen and driving goggles combination as early as 1920. It was hardly a hypothetical matter to Chubb: his wife had died a year earlier in a glare-induced car crash.
Chubb, however, lacked a practical way to mass-produce polarisers – or indeed to produce even a few. The most commonly used crystal polariser, the Nicol prism, would be ruinously expensive. Invented a century earlier, the Nicol prism consisted of a rhombohedral crystal of calcite split diagonally, with the two pieces stuck together with Canada balsam. “There are not enough of the great and precious rhombs of calcite employed in the classical Nicol prism to cover the headlights of the cars in a single city block,” Land pointed out. “Nicol prisms for a single headlight, if they could be collected, would cost a hundred times as much as all the rest of the car.”
Land’s solution was Polaroid: an inexpensive celluloid sheet extruded with a suspension of polarising herapathite crystals so that the crystals lined up in parallel. In 1936, New Yorkers visiting an exhibition at the Rockefeller Center marvelled at Polaroid sunglasses and 3D movies, but Land and his investors were already pursuing increasingly durable formulations of polarising sheets for what they considered Polaroid’s real market: headlights. “Night driving,” Land announced that year, “will become practically as safe and comfortable as daytime driving.”
Polarisers did have one drawback. The windscreen’s dimming effect on a car’s own lights meant it needed brighter lamps. But with the anti-glare filters, brighter headlights were no longer a problem, at least not for other drivers – to pedestrians Land rather unhelpfully suggested that they just look down more.
Success might have followed had it not been for the second world war. Both car manufacturers and Polaroid found their production lines requisitioned for the war effort, and headlights had to wait. After the war, in an attempt to drum up interest again, Land fitted three dozen test cars with polarisers. Journalists on a two-hour night-time jaunt were astonished by the effect.
So why don’t we have polarising headlights today? First, the US motor industry showed little interest in safety devices in the post-war years. “Automobile companies were not economically motivated, because they could sell all the cars they wanted,” Land later told interviewers. Polarisers were also in a double bind: to work, they would have to be adopted by every car manufacturer, but none was willing to be first. To be effective, there would have to be universal agreement or a law requiring every car on the road to have polarising lamps, something no manufacturer or politician dared suggest.
The experience left Land discouraged. “Intelligent men in groups are as a rule stupid,” he concluded. “And very intelligent men in the automobile industry were fantastically and simply stupid.” Land and Polaroid went on to make their fortune in another area altogether: instant photography.
“Intelligent men in the automobile industry were simply stupid”
With the rise of improved street lighting and multi-lane highways, the perils of the death dazzle largely receded to unfortunate encounters on rural roads. Yet inventors persisted in creating glare-blocking sunglasses and elaborate visors. Perhaps the most curious solution was patented by an ophthalmic surgeon in 1988: “liquid sunglasses”, an eye-drop gel to directly coat the eyeballs of drivers. But then the problem has never quite gone away, particularly given the modern popularity of SUVs. Comparatively lax regulation of headlight aiming in the US means that at their greater height, SUV headlights can shine right into the windscreens of passenger cars. Drivers themselves have also been changing: ageing eyes are more susceptible to glare, and baby boomers now run more risk of being dazzled.
Is a new anti-glare invention needed? Perhaps not. In 2001, a study by the American Automobile Association came to the startling conclusion that Land’s system remains the best: “Polarised lighting is the only countermeasure for headlight glare which has the potential to be used in all situations and resolve all problems.” All that was lacking, they noted, was precisely what had been missing in 1948: the will and patience to legislate for universal implementation.
Land himself always regarded Polaroid’s original purpose as his most important invention and the great tragedy of his career. “I didn’t set out to make money, but to get the polariser used,” he claimed in 1974. “It would have saved 40 lives a night.”
