Physics Stack Exchange
Physics Stack Exchange

Questions tagged [lenses]

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually aligned along a common axis. Lenses can also focus waves other than visible light, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses.

Relevant tags:

972 questions
4
votes
3 answers

Change in focal length of lens inside water

I read it on Yahoo Answers (link below) that the power of lens changes when the lens is placed inside water. But then, if we consider the formula f=c/2 , the radius if curvature of the lens still remains same, then, how can the focal length change?…
Harshal Gajjar
  • 362
3
votes
0 answers

Colour of artifacts in a lens flare

I'm adding a lens flare to an illustration; which got me thinking: Are the colours of the artifacts (hexagonal/circular) which appear in a lens flares purely random, or much like a rainbow (predictable and ordered)?
Ghoul Fool
  • 131
2
votes
2 answers

Is focal length of a planoconvex lens twice to the focal length of equiconvex lens from which the planoconvex lens was made?

If an equiconvex lens is divided equally, we will obtain a planoconvex lens. Let assume focal length of our equiconvex lens is 'f'. I would like to know what will be the focal length of planoconvex lens that we obtained after dividing equiconvex…
Nazmul Hassan
  • 151
2
votes
3 answers

Do eye-glasses decrease the Depth of focus?

I was reading up about Depth of Focus and wondered if glasses affect depth of focus. If yes, is it noticeable to the user?
Dale
  • 6,014
1
vote
0 answers

Hows lensmaker formula works? if Radius is zero?

I am doing my revision and there's such a question. However, when I tried to plug the values into the lensmaker formula, I find that one of the R is equal to zero, as it is not curved. $(n_2 -n_1)(1/r_1 - 1/r_2)$
Timothy Leung
  • 133
1
vote
2 answers

Is it possible to enlarge the output angle of a projector with outside lens?

I have a very small projector, with a small output angle (30 degree). In my current demand I want a bigger output angle(90 degree), so that I can get a bigger image within a given distance. Is it possible to get it by outside lens? The…
Timothy
  • 205
1
vote
1 answer

How are progressive lenses made to allow for continuous changes in prescription?

I recently got progressive lenses in my glasses and have been wondering how they achieve the (at least seemingly) continuous change in prescription? Is the glass formed to have a continually changing focal point or is it still made in segments…
thesquaregroot
  • 111
1
vote
0 answers

Determine the necessary radii of a double equiconvex lens, such that BFL=0

Sounds like a simple problem, but I have no training in optics: I need to work out the optimal radius to use for all four surfaces of a double equiconvex lens, so that a point light source close to the surface of the back face (bfl⋝0) projects…
tryblinking
  • 11
0
votes
0 answers

Is it possible to define the Point Spread Function for a lens?

I have seen several papers and reports in which the Point Spread Function (PSF) of a microscope is calculated and measured. In particular, as far as I understand, a light point source is placed in the specimen's plane along the focal axis of the…
Marco Gandolfi
  • 11
0
votes
0 answers

What are the equations for a 2D projection of the distortion induced by a cylindrical lens?

Imagine you have a cylindrical lens of power $C$ and of angle $\theta$ relative to some neutral 0 axis. I want to know, if you took a normal 2D image and shown it through that lens, what would the distortion look like? For example, suppose we shined…
Stan Shunpike
  • 4,081
0
votes
1 answer

Used Dobsonian reflector won't focus

I have collimated my 10" reflector telescope both manually, and later with a lazer, I have placed my eyepieces in the focusing tube, and rolled in, and out with no ability to resolve my target. Can someone give me an idea of what, besides bad…
dukem1
  • 1
0
votes
1 answer

Why do I need a longer focal length to take a picture far away?

Can someone tell me why I need to use a lens with a longer focal length when aiming to take pictures of distant objects?
Eliza
  • 2,137
0
votes
1 answer

How to determine best lens to use to clearly see in the seawater?

I'm trying to determine what is th best lens to use in the seawater. Lets say I'd like to open my eye in the seawater (no mask or any air between the eye and water), see thru lens located about 20 mm from my eye and get the sharpest, realistic…
xbuster
  • 11
0
votes
1 answer

Lens and Mirror Grinding

I am actually grinding my own lenses ( I am trying). Now I have been continuously using the chordal stroke for atleast 3 hours but i am unable to see any depreasion be it convex or conacve on the tool or the mirror respectively. I have been applying…
Shashaank
  • 2,767
0
votes
1 answer

What is the formula for determine heating produce by a lens?

When I put a lens along the the sun it convert the sun energy to heat and maybe fire the substance beyond the lens. How could I determine the heat produced and what is the formula?
amirrez kf
  • 1
1
2