Nowadays cameras are
one of the hottest selling items in all of consumer electronics. But as anyone
who has ever seen them can attest, the images that come out of these camera
phones leave plenty to be desired. Part of the problem is their CMOS imaging
chips, which typically have a censor array of only about 300 kilo pixels-a
quarter or less of the number in a low-end digital camera. But the major
problem is their tiny, fixed focus lenses. These fixed focus lenses are very
small but they have poor light gathering power and resolving power.
Conventional auto focus
systems used in high quality digital cameras use motors and gears to shift the
position of the lenses. They have high quality, but are difficult to
miniaturize because of the gears and motors.
‘FLUID FOCUS LENSES’
can combine both these qualities. It is a special type of lens developed by
Philips Research Laboratories. It uses the principle of a human eye. Like the
lens of a human eye it focuses on objects at different distances by varying the
shape of the lens rather than by varying the relative positions of multiple
lenses. It uses electrostatic force to alter the shape of a drop of slightly
salty water inside a cylinder 3 millimeters and 2.2 mm long. So it can be made
to be very small and the images taken by using these lenses will be having very
high quality.
These superior
capabilities of ‘FLUID FOCUS LENSES’ should make them ideal not only in camera
phones but also in products whose design constraints demand a tiny but capable
optical systems.
Camera
A camera is a device that captures an
image on a film for an optical camera, or a CCD(charged coupled device) for a
digital camera. A simple camera consisting of a lens, a shutter, a media
holder, and a viewfinder. The main part of a camera is lens. A lens is
an optical device that focuses light rays. In cameras, the lens is the device
on the front face (or in a tube extending from the front face) that gathers the
incoming light and concentrates it so that it can be directed toward the film
(in an optical camera) or the imaging device (in a digital camera).
The term focus means to move the
lens or film/image sensor in order to record a sharp image.Then the term focal
length describes the distance from
the surface of the lens to the focal point or center point at which light rays
converge; the focal length determines the length of the lens.
Image Formation by A Lens
Image
formation by a lens depends upon the wave property called refraction.
Refraction may be defined as the bending of waves when they enter a medium
where their speed is different. Since the speed of light is slower in a glass
lens than in air, a light ray will be bent upon entering and upon exiting a
lens in a way that depends upon the shape and curvature of the lens. In the
case of a converging lens such as the double convex lens shown below, parallel
rays will be brought together at a point.
The distance from the
lens to this principal focus point is called the focal length of the lens and
will be designated by the symbol f. A converging lens may be used to project an
image of a lighted object. For example, the converging lens in a slide
projector is used to project an image of a photographic slide on a screen, and
the converging lens in the eye of the viewer in turn projects an image of the
screen on the retina in the back of the eye.
