THE LIGHT WE BRING

FIRST there was darkness, then there was light, carriage light. Horse carriage light. At the dawn of the age of the horseless carriage, the world was quite hostile to the idea of the car and at times they treated it like a deranged distant relative; they let it roam around but it had to have someone to chaperone the proceedings.

At first, they had people carrying flags or warning placards walking ahead of the cars. This sort of limited the speed of the car to painfully slow and pretty much limited driving as a sun-up activity.

Obviously the man-ahead-of-horseless-carriage age did not last long and soon car drivers were bolting on carriage lamps to their primitive cars but those were not really meant to light the way, instead these lamps sort of cast a soft haze on the surroundings to help the carriage driver see a bit better than under moonlight.

Not really useful for high-speed night driving.

The development of acetylene lamps that burnt the gases created by combining calcium carbide and water helped to create a light that is bright and constant. This type of lamp can still be bought at hardware stores in small towns.

Calcium carbide is used as one of the components for fertiliser and, therefore, commonly found at farm supply stores. It is particularly con- venient that it can also be used as lighting source.

These acetylene lamps were housed in a copper or bronze housing with a reflector behind the flame and glass in front.

The glass doesn’t really do much other than keep wind and dirt and dust out and the light came out flooding in a barely controlled way, this unfocused light meant that drivers still could not see very well at night.

The Americans pioneered electric lamps for cars in the 1890s but these simply replaced the acetylene lamp and did not improve much on the light management technology.

What was needed was a way to manage the light rays and direct them to the road rather than allow it to stray every which way and causing glare on pedestrians and oncoming motorists.

The principle of lensing is well understood by this time and the Fresnel was already widely used to focus and direct the limelight used in light houses. Although limelight in theatres were not as well focused by that time, they acted more like floodlights.

Corning Glass was the first to offer technical glass lens for car headlamps. The glass has a familiar Fresnel patterns although the aim of the lights were not as precisely controlled as in modern halogen or High Intensity Discharge headlamps in modern times.

At least with this lens, light was focused downwards and onto the road rather than at the trees and eyes of pedestrians.

If we look at the development of headlamp Fresnel, it is clear that with time engineers understood better the role that light plays in safety and began designing lenses that would direct the left and right side of the lamps differently and different again in left and right hand drive cars.

Modern halogen and HID lamps are focused further on the passenger side of the road and shorter on the driver side. This is to help the driver see the edges of the road better while reducing glare for oncoming motorists.

The Fresnel is designed to work with the different bulb designs which have different filament combinations for main and dipped beam.

Some bulbs have reflectors on the top of the bulb itself, others may have reflectors on the front of the bulb and although you may be able to swap them, depending on the socket design, they would not work as well and may even be illegal due to their wrong light spread.

With the advent of projector style headlamps, the problem was solved with a combination of filament and reflectors that form the shape of the beam and the lens that then directs the beam according to the requirements of driving.

Modern projector headlamps tend to come with self-levelling feature, which is an electronic device that senses the angle of the lights and ensures that it is not pointing too high.

The level of intelligence and automation in modern headlamps is impressive and many can track corners according to steering angle while others can detect oncoming traffic and automatically select main or dipped beam to ensure maximum illumination.

Light Emitting Diodes (LED) is the new lighting medium and they can be super bright. However the nature of the design and construction of these lamps mean that light is highly scattered at source and require careful reflector and lens designs to ensure effectiveness.

LED lamps also tend to generate a lot of heat and this poses some questions about its installation as they typically come with significantly sized heat sinks.

The compact design of medium brightness LED means they are a popular way of injecting new design flair in modern cars.

Sequencing the turn indicator and designing dancing headlamps start-up sequence is becoming a common feature among luxury brands and even brands aspiring for a luxury image.

For the moment it seems LED will stay for some time as it is a highly efficient source of light and can generate sun-like brightness without demanding too much power from the car.

When cars become self-driving, headlamps would be more of a design element and less of a safety feature.

So enjoy the light while it lasts.