Why zone plate has multiple foci?
Zone plate has multiple foci For a fixed distance of the object, a lens produces only one image, where as a zone plate produces a number of images. In other words, it has multiple foci. It is because the number of half-period zones contained in an area depends upon the position of the screen.
What is zone plate derive an expression for its Focal length?
The focal length of a zone plate is given by the relation f = rn2/n٨, Focal length of a zone plate is the distance measured along its axis at which the maximum is produced when the source of light is located at infinity i. e., when a plane wave front is incident on the zone plate.
How a zone plate is constructed?
The zone plate geometry is constructed by alternating transparent and opaque zones, where the radius of the nth zone is given by Eq. (7). All zone plates with radii given by Eq. (7) will bring plane wave illumination with wavelength λ to focus at a distance f past the lens.
How does a positive zone plate differ from a negative zone plate?
Zone plate: A diffracting device used to experimentally demonstrate the diffraction effect. Positive zone plate: Odd zones are kept transparent to the light. Even zones are made opaque.
What is Gabor plate?
The Gabor zone plate, which suppresses the higher-order foci to a pair of conjugate foci, is an attractive alternative to the conventional Fresnel zone plate. In this work, we developed a novel type of Beynon Gabor zone plate based on perfectly absorbing carbon nanotube forest.
What is a zone plate and how is it made explain how a zone plate acts like a convergent lens having multiple foci?
Answer: A zone plate is made by drawing concentric circles whose radii are proportional to the square root of natural numbers and alternate annular regions are shaded. The zone plate is used to focus light or for example to form images using X-rays and microwaves.
Does zone plate behave like?
zones, behaves like a lens which is simultaneously both converging and diverging. Improvements in the performance of such zone plates has recently led to some attention being given to their potential use as lenses in certain applications. of the zone plats and a hologram may be considered as a generalized zone plate.
What do you mean by zone plate?
Definition of zone plate : an optical device that consists of a series of concentric opaque rings of such width that rays from alternate half-period elements are cut off and that has some properties of a converging lens.
What is half period zone plate?
The distance between wavefront and point P is OP = b. point O is called the ‘pole’ of the wavefront corresponding to P. To find resultant intensity at point P due to wavefront, we divide the wavefront into a concentric half period zone. These period zone are known as fresnel’s half period zone.
What is the theory of zone plate?
A zone plate is a device used to focus light or other things exhibiting wave character. Unlike lenses or curved mirrors, zone plates use diffraction instead of refraction or reflection. Based on analysis by French physicist Augustin-Jean Fresnel, they are sometimes called Fresnel zone plates in his honor.
What is half period zone?
What Is Half Period Zones? According to a very famous scientist named Fresnel, the entire area of wavefront can be divided into be ‘n’ number of smaller regions of zones and these zones are referred to as half period zones.
What is positive zone plate?
(2) Positive zone plate : When odd zones are kept transparent to the light and even zones are made opaque, then it is called positive zone plate.