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

Click For Summary

Discussion Overview

The discussion centers around determining the angle of deviation for plano-concave lenses, with a focus on how this relates to the curvature and material of the lens. Participants explore the implications of light ray behavior as it passes through these lenses, particularly in the context of a project involving illumination.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • Some participants inquire about the specific angle of deviation for plano-concave lenses and request background information on how rays are traced through them.
  • One participant notes that the angle of deviation varies for different rays and asks for clarification on which ray the angle is being calculated for.
  • A participant mentions their project involving the divergence of sunlight using a plano-concave lens and seeks to understand the relationship between angle of deviation, lens curvature, and material.
  • Another participant provides a formula relating the cone angle of light to the numerical aperture and focal length, suggesting that the same calculation applies to both plano-convex and plano-concave lenses, while also noting the neglect of aberrations.
  • There is a question about deriving the angle of deviation for parallel rays and how light intensity is affected as it passes through the lens.
  • One participant states that the deviation of a ray depends on its height when it hits the lens, indicating that rays passing through the center will propagate undeviated.

Areas of Agreement / Disagreement

Participants express differing views on the application of plano-concave lenses and the specifics of calculating the angle of deviation, indicating that multiple competing perspectives remain. The discussion does not reach a consensus on the exact method for calculating the angle of deviation.

Contextual Notes

The discussion highlights limitations in the assumptions regarding ray behavior and the effects of lens characteristics on light propagation, which remain unresolved.

omega360
Messages
5
Reaction score
0
hello,
how can i find out the angle of deviation for plano-concave lenses.
thanks
 
Science news on Phys.org
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?
 
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?
 
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
 
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.
 
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:
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 propagate undeviated if it passes through the center of the lens, for example.
 

Similar threads

High School The principle of operation and application of optical lenses
  • · Replies 14 ·
Replies
14
Views
2K
Undergrad Image construction with concave and convex mirrors
  • · Replies 4 ·
Replies
4
Views
2K
Graduate When should I analyze optical problems using ray tracing vs. wavefront analysis?
  • · Replies 12 ·
Replies
12
Views
2K
Undergrad Is Geometrical Optics Essential for a Deeper Understanding of Light?
  • · Replies 10 ·
Replies
10
Views
3K
Undergrad How to couple light from a very small source into spectrometer?
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad How Can I Build an Effective DIY Helmet-Mounted HUD?
  • · Replies 19 ·
Replies
19
Views
5K
Undergrad Digital Micromirror Device based optical setup
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Help Needed for Lens Selection for Fiber optics
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Plane wave decomposition method in scalar optics
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Using Diffraction (i.e., Fresnel Zone Plate) to defocus/diverge light
  • · Replies 2 ·
Replies
2
Views
2K