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♥ Monday, August 23, 2010 ♥

In 1508, Leonardo Da Vinci described the contact lens as a convenient means of correcting vision. Today, they’ve become so widely accepted that it’s not unusual for people to wear colored contact lenses purely for cosmetic reasons.

Contact lenses are medical products, so it’s necessary to obtain them from a qualified optician who’s authorized to prescribe contact lenses. With a thorough eye check-up and proper aftercare, contact lenses are quite safe. Problems usually occur when the eye examination is hastily or badly performed, the wrong type of lens is chosen and the lenses are poorly maintained or cleaned.

There’re two main types of contact lenses: soft lenses and rigid (hard) lenses. Both have their advantages-soft lenses are more comfortable, but hard lenses keep shape better and may therefore provide sharper vision.

A contact lens is really a foreign object in the eye, so it must be handled and maintained properly to prevent complications. Contact lenses must be cleaned and disinfected after each wearing. Cleaning products and schedules very according to the type of lens prescribed. Follow instructions on the package carefully. Clean with enzyme tablets to help remove protein deposits weekly. Don’t mix or substitute solutions from different cleaning systems. This could lead to discolored lenses, eye discomfort or injury.

Remember to wash and rinse your hands thoroughly with soap and water before handling your lenses. Clean, rinse and air-dry your lens case. Dirty contact lens cases can be a source of bacterial growth. Replace your lens cases regularly. Don’t wear lenses beyond the recommended number of hours. Don’t wear your lenses while sleeping. Discard soft lenses after 12 to 18 months of use. Hard lenses need to be replaced after 5 years.

Don’t use saliva to wet your lenses and don’t use home-prepared saline, distilled water or tap water for cleaning your lenses. These solutions may not be sterile. Keep your contact lenses moist. Hard lenses may warp if allowed to dry and soft lenses may harden, shrivel and break. Don’t allow your lenses to come into contact with cosmetic lotions, creams or sprays. It’s best to insert your lenses before putting on makeup and to remove your lenses before cleaning face. Water-based cosmetics are less likely to damage your lenses than oil-based products. Use appropriate protection for the eyes when necessary. For example, during water sports like swimming, surfing, windsurfing and sailing, goggles should be worn to protect both the user’s eyes and lenses.

Daily disposable lenses may useful for those who have trouble keeping their lenses clean. Disposable lenses are worn for a single day then thrown away and replaced with a new pair. During camping or long trips, use extended-wear lenses to minimize handling. Extended-wear soft lenses can be worn up to 6 days continuously and the discarded. However, this type of lens is not recommended for daily long-term use. See your contact lenses practitioner or family doctor if you experience pain, discomfort, redness or itching of the eye, or if you find your sight is blurred.

Labels: brainy, contact lens, project

♥ Last Written @ 2:23 AM

♥ Saturday, August 7, 2010 ♥

The discovery that sounds could travel by radio waves set several scientists thinking. If sound could be transmitted in this way, what about pictures?

The main problem faced was scanning, which was how to convert picture into a continuous sequence of information. When a person looks at a picture on a television screen, he is actually seeing millions of tiny dots of light. These dots are arranged in lines. On a modern television, there’re 625 lines on the picture. The more lines the picture has, the clearer and precise the picture is. This is because the image is broken up into very tiny parts.

Some of the first pioneers of television looked at electronic methods. In 1923, a procedure for converting an image into electrical signals was developed by Vladimir Zworykin, a Russian-born American.

Another pioneer was John Logie Baird, a Scottish engineer-turned-inventor who developed television in a different way. He had struggled unsuccessfully for 9 years until one day he came up with an idea for a mechanical scanning system; a system which was based on an invention by Paul Nipkow, a German student. Nipkow had the idea of cutting up images into lines and he produced an ‘electric telescope’ which comprised a disc pierced with a spiral of holes at the edge. The disc would divide the object into a series of lines when it was spun in front of an object. Baird applied for a patent to use Nipkow’s idea to make television. He managed to produce a flickering, blurred picture in 1925.

Braid greatly excited by his success, borrowed money to improve his invention. He rented a workshop in London to continue his work. He televised a ventriloquist’s dummy to the public at his workshop. The image was very dim and blurred as it was made up only with 8 lines. However, it was a success despite the poor quality. The public began to believe in the possibilities of this new communication system.

Baird set up his own company and continued to work to improve the quality of the images. The BBC was founded in 1922 to broadcast radio programs. Baird persuaded them to transmit television service. Meanwhile, other companies were working on electronic methods. In 1933, Zworykin patented the ‘iconoscope’, a camera tube that converted an image into electrical pulses, which was used by the Radio Corporation of America in 1936.

The electronic method was more sophisticated and could produce better quality pictures than Baird’s mechanical device. There were several drawbacks to the latter’s system. The camera was immobilized so anyone televised had to stay in one position. Besides, those televised were asked to wear heavy make-up so that their features could be seen. This was due to the poor quality of the picture. They were also almost blinded by the flickering light from the machine. Finally, the system’s frequent breakdowns proved to be the last straw.

For a while, the BBC used both mechanical scanned system and electronic system for their programs, but they finally dropped the former favor of the latter in 1937. Baird was bitterly upset over the decision. However, Baird’s first flickering pictures earned his credit as the inventor of the television, despite other pioneers who had been working on producing more advanced and technological equipment than Baird.

Labels: brainy, lines, project

♥ Last Written @ 7:31 PM