Angle Of Deviation - An Optics Problem, help needed in optics

In summary: This is because the focal length is the distance from the center of the lens to the point where the ray hits the lens. When a ray hits the edge of the lens, it is refracted and its momentum carries it over the edge. This changes the angle of the ray and can cause it to diverge from the original path. The intensity of the light is then decreased because it has to travel a longer distance to reach the observer.
  • #1
omega360
5
0
hello,
how can i find out the angle of deviation for plano-concave lenses.
thanks
 
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  • #2
omega360 said:
hello,
how can i find out the angle of deviation for plano-concave lenses.
thanks

Could you please provide us some background on plano-concave lenses, and how rays are traced through them? What do you think the relevant equations are for the "angle of deviation?"

Is this homework or coursework?
 
  • #3
If you send (for example) a beam of parallel light rays into a lens (any lens, not just plano-concave ones), they come out at various angles, different angles for different rays. This is what makes lenses useful: they change the convergence or divervence of a whole collection of light rays.

So, you need to be more specific. Which ray do you want the angle of deviation for?
 
  • #4
i am working on a project related to illumination and i need to diverge rays of the sun using plano concave lens. so, i need to find out how the angle of deviation relates to the curvature of the lens and the material of the lens

please help me
 
  • #5
That's an odd application, but in any case, the calculation is the same for plano-convex and plano-concave. The cone angle of light 'q' (given by the numerical aperture NA = sin(q) for a lens in air) is the ratio of focal length 'f' to lens diameter 'D': NA = 2*D/f. So sin(q) = 2*D/f, and the cone angle the inverse sine of 2*D/f. The focal length is calculated from the radius of curvature of the curved face.

Just remember to keep track of the sign.

This calculation neglects aberrations, so the answer is not exact.
 
  • #6
That's an odd application, but in any case, the calculation is the same for plano-convex and plano-concave. The cone angle of light 'q' (given by the numerical aperture NA = sin(q) for a lens in air) is the ratio of focal length 'f' to lens diameter 'D': NA = 2*D/f. So sin(q) = 2*D/f, and the cone angle the inverse sine of 2*D/f. The focal length is calculated from the radius of curvature of the curved face.
Still didn't get how i could derive how much angle light would deviate after it passes through the lens. also what if the rays are parallel to the principal axis. what would be angle 'q'??

also could i know how light intensity is affected by it passing through the lens.
 
Last edited:
  • #7
The deviation of a particular ray through a lens with in general depend on the ray height when it hits the lens. A ray will propogate undeviated if it passes through the center of the lens, for example.
 

1. What is the angle of deviation in optics?

The angle of deviation in optics is the angle between the incident ray and the refracted ray as they pass through a medium with a different refractive index. It is a measure of the bending of light as it travels through a medium.

2. How is the angle of deviation calculated?

The angle of deviation can be calculated using Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the refractive indices of the two media.

3. What factors affect the angle of deviation?

The angle of deviation is affected by the refractive indices of the two media, the angle of incidence, and the wavelength of light. It also depends on the material properties of the medium, such as density and temperature.

4. How is the angle of deviation used in optics?

The angle of deviation is an important concept in optics and is used to understand the behavior of light as it passes through different media. It is also used in the design and analysis of optical instruments, such as lenses and prisms.

5. Can the angle of deviation be negative?

Yes, the angle of deviation can be negative if the refracted ray bends towards the normal instead of away from it. This can happen when light passes from a less dense medium to a more dense medium, or when the angle of incidence is greater than the critical angle.

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