What is relation between focal length and symmetry of lens?
Answers
Answered by
0
hey here is your answer
Based on Geometrical Optics (Geometrical optics) focal length is half of the radius of curvature. There are some assumption for this, i.e. lens is spherical and the refractive index is uniform (cmiiw).
However, most lens materials have dispersive properties which means that the focal length varies with the wavelength of the light. This dispersive properties of the lens is not a problem for most daily application for example spot light used at home usually has a rainbow on the edge of the spot, this is caused by the dispersive property of the focusing lens used to concentrate the light.
In some other application which requires color accuracy such as photography or microscopy, a small dispersion can cause a huge problem. In photography, the dispersion can be perceived as faint colored photographs. This happens when there are some part of the visible light spectrum (our eyes perceive this spectrum as color) that are properly focused on the sensor surface while some others don’t, the difference maybe only some micrometers but if the image is enlarged then the effect is visible. The same thing applies for microscopy. This effect can be minimized by using aspherical lenses (out of topic).
There are some special lenses that I know (there are a lot more):
GRIN lens (Gradient-index optics), the focal length varies with the distance from the radius. Usually used for focusing light on fiber optics.Another kind of special lens is Fresnel Lens (Fresnel lens ) usually used for making magnifier sheets used for reading books.Negative refractive index lenses. Called as the superlens (Superlens ). I don’t know much about this, I once collaborated with a research group that fabricate negative refractive index materials on lab scale.
So, focal length of the lens is actually an average focal length of the whole light spectrum that can pass through the lens (the spectrum can be limited by applying coating to the surface of the lens). Unless the lens is spherical and uniform, the focal length might not be half of the radius of curvature.
make sure it brainliest please
Based on Geometrical Optics (Geometrical optics) focal length is half of the radius of curvature. There are some assumption for this, i.e. lens is spherical and the refractive index is uniform (cmiiw).
However, most lens materials have dispersive properties which means that the focal length varies with the wavelength of the light. This dispersive properties of the lens is not a problem for most daily application for example spot light used at home usually has a rainbow on the edge of the spot, this is caused by the dispersive property of the focusing lens used to concentrate the light.
In some other application which requires color accuracy such as photography or microscopy, a small dispersion can cause a huge problem. In photography, the dispersion can be perceived as faint colored photographs. This happens when there are some part of the visible light spectrum (our eyes perceive this spectrum as color) that are properly focused on the sensor surface while some others don’t, the difference maybe only some micrometers but if the image is enlarged then the effect is visible. The same thing applies for microscopy. This effect can be minimized by using aspherical lenses (out of topic).
There are some special lenses that I know (there are a lot more):
GRIN lens (Gradient-index optics), the focal length varies with the distance from the radius. Usually used for focusing light on fiber optics.Another kind of special lens is Fresnel Lens (Fresnel lens ) usually used for making magnifier sheets used for reading books.Negative refractive index lenses. Called as the superlens (Superlens ). I don’t know much about this, I once collaborated with a research group that fabricate negative refractive index materials on lab scale.
So, focal length of the lens is actually an average focal length of the whole light spectrum that can pass through the lens (the spectrum can be limited by applying coating to the surface of the lens). Unless the lens is spherical and uniform, the focal length might not be half of the radius of curvature.
make sure it brainliest please
Similar questions