THE BIRTH OF MODERN TIMEKEEPING

When the Olympic Games resumed in 1948 for the first time since 1936, new timekeeping devices included the photoelectric cell, the slit photofinish camera and the athletics starting block. OMEGA was there to help usher in the era of modern timekeeping.

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THE PHOTOELECTRIC CELL

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The London 1948 Olympic Games introduced a number of technological innovations changed Olympic Games timekeeping dramatically. That year, OMEGA used its photoelectric cell for the first time at a summer Olympic Games. The now ubiquitous “slit” photofinish camera, developed by a British firm called Race Finish Recording Company, also made its Olympic Games debut.

This photoelectric cell could determine precisely when the runners crossed the finish line, ultimately eliminating the need for the familiar tape at the finish line. However, in an event like the 100-metre sprint, the athletes finished so tightly grouped that it was sometimes impossible to tell, beyond a shadow of a doubt, what the finishing order had been. The photofinish camera recorded an image that could be developed in about eight minutes, removing any question about who would claim the gold, silver and bronze medals.

More than six decades after these groundbreaking technologies were introduced, their descendants remain an essential cornerstone in the timing of world-class track and field events. The combined use of photoelectric cell technology and photofinish images changed sports timekeeping forever.

No matter how well intentioned, the human eye has its limitations. At the finish line, it was replaced by a highly sensitive photoelectric cell which instantaneously stopped the chronograph, while a lightning-fast electric current eliminated inconsistencies caused by timekeepers’ reaction times. In sprints and races with grouped finishes, there was the possibility that there would be no space between the athletes crossing the finish line so other timekeeping systems had to be used in support of the photoelectric cells. The photoelectric cell placed at the finish line dramatically outperformed all previous timing devices and in time, replaced the finishing tape.

In 1948, the results recorded by automatic timing devices were not used officially at the events in London. The first photofinish equipment only served to aid the judges in their determination of the rankings, most-famously in the men’s 100-metre sprint. It would be 20 years before the automatic times were accepted as official at the Mexico City 1968 Olympic Games.


HOW THE PHOTOFINISH CAMERA WORKS

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The camera used in London was essentially a standard 35 mm still frame camera mounted on a box that contained the film cartridge. On the side of the track opposite the camera was a drum roller which was the source of the incremental numerical markers on the film. These markers appear as a continuous line but were, in fact, lapsed-time images of the drum roller. The speed at which the film moved through the camera could be adjusted according to the demands of each event. For example, the film would be advanced more quickly for a sprint than for a walk.

Following an event the film was processed in a developing agent and removed from the casing to be rinsed. The goal was to achieve a total development time of three minutes so that the final results could be visually verified as quickly as possible. All of this was activated by the same start gun mechanism which triggered the chronographs.

Despite the differences between the original film-based cameras and the current digital models, the sensors that trip the cameras and chronographs remain fundamentally the same as the first devices used in 1948. A beam of light from the photoelectric cell is projected across the finish line, and at the instant the runner interrupts the beam, the chronographs are stopped and the camera verifies the finishing order.

The photofinish camera was immediately put to the test in the historic 100-metre final where two Americans, Harrison Dillard and Barney Ewell, fought to an exciting finish. Both men clocked the same time of 10.3 seconds and because of the elasticity of the finishing tape, both had touched it. Ewell, believing that he had won, reacted jubilantly but when the judges checked the photofinish image, they named Dillard the winner and he claimed the gold medal. Ewell also saw the photograph and immediately accepted the result.


TECHNOLOGY TODAY

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At the London 2012 Olympic Games, OMEGA will deploy 420 tons of equipment including scoreboards as well as 180 kilometres of cabling. Around 450 professional timekeepers and data handlers will be assisted by some 850 selected and trained volunteers.

Improvements in timekeeping technology allow more precise results than ever. Although today’s photofinish cameras are more than ten times more accurate than their predecessors were 64 years ago, the basic principles remain the same. Today we call our photo finish camera the Scan’O’Vision. The main difference between this camera and its trailblazing ancestor is that instead of using film, it records its images digitally.

The image it sees is one pixel wide, scanning at 2000 frames per second. The image produced is 2000 pixels high with length determined by the athletes’ spacing. Three years ago, the camera was roughly a quarter of the size of the current one which houses an on-board computer. The aim is to deliver the results of the first three finishers within fifteen seconds of the end of the race. The old drum roller which created the continuous image behind the athletes has been replaced by a “line scanner” which displays an image as a strip of LED lights at a frame rate relative to the camera.



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The diagram above shows the setup of the timing equipment. The entire data management system, including the photofinish camera itself, is set up in the control room. At least two timing systems are installed at the venue – one for primary use, the other as a backup. Technicians in the control room can change systems with a single switch in the unlikely event that one system fails. The photo cells also record a time but are only used for reference as the official time is given by the photofinish camera. The photo cells can be used in some skiing events as there is considerable distance between the competitors; the process is also simplified as they cross the finish line in single file.

There are two photo cells at the end of the track, set at different heights in order to ensure that they are triggered by a runner’s torso and not his arm. For an accurate result, both photo cells need to be triggered to establish and record the race time. There are some key factors in determining the results in a track race. A false start is declared if an athlete begins to run less than a tenth (100/1000th) of a second after the start pistol has been fired. It has been determined that human beings require at least this much time to react to a signal.

If wind speed is greater than two metres per second, the result cannot be registered as a record on any level. Depending on the direction of the wind, it could lead to times which are greater or lesser than those merited by the athletes’ performances. The entire photofinish camera system is calibrated by the light produced by the start gun when it is triggered. The start mechanism is aligned to this instantaneous occurrence.

In 2012, state-of-the-art timekeeping and data-handling technology developed by OMEGA and adapted to the requirements of each sport will be used for every event – the equivalent of 37 simultaneous world championships!


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