All Questions
62
questions
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answers
36
views
Luneburg lens in a medium
A Luneburg lens is a spherical lens with a gradient refractive index. It has the interesting property that light coming from focal length of infinity will be focused on the surface of the lens.
The ...
- 284
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votes
0
answers
25
views
How to Calculate Focal Length when in another medium?
How do you calculate the focal length of a lens when it is placed into another medium, if I only have the focal length of a lens in the air? I understand that the lensmaker's equation should be used, ...
- 187
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votes
1
answer
45
views
What is a convex-concave lens?
I came across this term while studying for optics, and I'm unsure as to what this means. My thinking is that it might be a meniscus lens, but the text separately give two different models for each ...
- 187
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votes
0
answers
24
views
Lens maker’s formula from parabolic approximation
I’m attempting to derive the lens maker’s formula for a thin or thick lens using the parabolic approximation.
I’m familiar with the other proof using the law of refraction and different angles.
The ...
- 1
2
votes
1
answer
201
views
Lenses and missing reflection
I am wondering why reflected rays are not considered with lenses. If a ray strikes a surface, another is reflected off that striking point; however, this is not added when studying lenses, only ...
- 23
0
votes
1
answer
39
views
Magnification of closely packed thin lenses, or of closely packed lens and mirror
I was taught how to calculate the equivalent foci in both the cases. And since the formulae resemble the simple mirror and lens maker formulae, teacher said that this system is behaving like a single ...
- 41
0
votes
1
answer
45
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As we all know a convex lens doesn't exactly converge all rays parallel to it's axis on a single point. So I want to find one such figure
Writing a differential equation for such a figure is an uncomplicated task. It can be accomplished by using snell's law. But the resulting equation probably isn't solvable. I put it in wolfram alpha ...
2
votes
1
answer
200
views
Use of sign convention two times in ray optics
In this particular derivation of refraction happening at a spherical surface in terms of its radius of curvature , image and object distance and refractive index is done by my book as shown
When we ...
- 441
1
vote
0
answers
179
views
What causes the distortion of an image when seen through a water droplet?
I'm trying to explain what causes an image to be distorted when seen through a water droplet.
Specifically, my example is that of a drop of water on a car window. We can see that the image is reversed,...
0
votes
0
answers
127
views
Optics question: Simple way to transform a parallel bundle of collimated beamlets into a converging (diverging) bundle of collimated beamlets?
I'm searching for an optical element that converts a parallel bundle of individually collimated beamlets into a converging or diverging bundle of still collimated beamlets (or vice versa). So ...
- 181
1
vote
2
answers
422
views
Hyperbolic lens shape and aspheric surfaces
In Optics, Hecht, the author states that the perfect surface for a lens shape will be a hyperbola.
He essentially derives this answer by writing the optical path length from F1 to A, then A to D, and ...
- 59
1
vote
1
answer
106
views
Thin layer of air between lenses in contact
consider the following case for thin lenses
Case 1: lens between two different medium
applying refraction through curved surfaces two times and subtracting -
$$\frac{\mu_{oil}}v - \frac{\mu_{air}}u = ...
- 379
0
votes
2
answers
907
views
Can we tell on which side of a lens an image appears?
Suppose I look through a single, thin, converging lens at an object on the opposite side. Depending on where the object is placed, the lens will either produce a real image on the side of the lens ...
- 8,343
2
votes
1
answer
280
views
Geometric optics explanation of lateral (transverse) chromatic aberration
The majority of pictures explaining lateral(transverse) chromatic aberration look like this
Here the focal point for red light is shifted closer to the optical axis and the focal point for blue light ...
2
votes
3
answers
440
views
How does the combination of lens create a sharper image?
There's a line in a book which states that the combination of lens helps create a sharper image, but I don't understand how. Does more magnification mean sharper image?
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