Seeing things Alhazen

Seeing things

The bright sparks illuminating the mysterious world of LIGHT AND SIGHT

People have long been fascinated by what light is or how our eyes detect it. Here are some of the trailblazers who saw the light.

Did you know? Camera obscura is Latin for “dark chamber”. This device led to the development of photography.

16th-century spectacles Light rays from the object travel in straight lines. This image on the screen appears upside down.

Alhazen

In the 10th century, this Islamic scholar wrote the highly influential Book of Optics.

Through experiment, he proved that vision occurs when light enters the eye. He also discovered that refraction, or bending, of light is caused by light rays moving at varying speeds through different materials. Alhazen noticed that when light travels through the small hole in a CAMERA OBSCURA, the projection on the other side appears upside down. He therefore worked out that light rays must travel in straight lines. Camera obscura

Roger Bacon

This 13th-century English scholar placed great emphasis on EXPERIMENT AND

OBSERVATION in science. Inspired by the work of Alhazen, he investigated the effects of mirrors and magnifying glasses.

Bacon was one of the first people to suggest that lenses could be used to improve a person’s vision. In 1267, Bacon gathered all his major ideas into a big book called Opus Majus.

Willebrord Snell

In 1621, this Dutch astronomer used mathematics to show that it was possible to predict HOW MUCH A RAY OF LIGHT WILL REFRACT, or bend, when passing from one medium to another. This formula was called Snell’s law and it forms the basis of modern-day fibre optics. This technology uses light energy to transmit data via fibre-optic cables (thin glass or plastic fibres that carry data) for many wired phones and the Internet.

Leeuwenhoek’s microscope

Antonie van Leeuwenhoek

Despite having no formal education, this 17th-century Dutch textile merchant became a pioneer of microbiology. Using a homemade microscope, he examined a drop of pond water, and was astonished to see tiny organisms – the

FIRST OBSERVED BACTERIA. He built several hundred microscopes and went on to make many more discoveries, including blood cells.

Patricia Bath

This laser scientist is known for her innovative research in the areas of blindness prevention, treatment, and cure.

Her achievements include the invention of a new device, the LASERPHACO

PROBE, used in eye surgery to correct cataracts – a condition that can cause blindness. Patricia Bath was the first female African-American doctor to patent a medical invention.