The tag has no usage guidance.

learn more… | top users | synonyms

1
vote
1answer
25 views

Can focal point of a lens be a line instead of a point

Is there any lens OR can we have a lens that will focus light in form of a line instead of a point. Some sort of a rectangular convex lens.
0
votes
2answers
644 views

How to use a magnifying glass or any lens to enhance small light power?

I am currently trying to amplify a tiny amount of light so that a photodiode will recognize it. In order to amplify the light I thought about using a magnifying glass since I got to know that such ...
-1
votes
0answers
29 views

How did physicists determine how to orient the wave guides for this optical meta lens?

What kind of physics and mathematical tools are used to develop this technology? As described in the link, Researchers have demonstrated the first planar lens that works with high efficiency ...
1
vote
0answers
15 views

Spherical aberration: circle of least confusion and diffraction limited spot size

I need an estimate of the relative sizes of the circle of least confusion (spherical aberration) and the diffraction limited spot size for typical real lenses. I've seen plenty of discussions, but ...
1
vote
0answers
15 views

Increase the collection effciency of lens array

In an experiment I am trying to image a phosphor surface on a camera using a 3x zoom lens. The distance of phosphor surface to lens input surface is ~100 mm. The effective focal length of the zoom ...
0
votes
0answers
9 views

How to calculate the lensing amplification of the weak field images in schwartzchild metric?

In Strong field limit of black hole gravitational lensing, Bozza et al state (without proof) that the amplification of each weak field image is given by $$ \mu_{wfi}=\frac{1}{\beta}\sqrt{\frac{2\,D_{...
0
votes
1answer
140 views

Confused regarding sign convention of silvered plano convex lens

I'm totally confused while finding the sign convention of a silvered plano convex lens. I know that equivalent power of such a system can be found by adding the power of the mirror and twice the power ...
1
vote
0answers
18 views

What is the difference between $\theta^{0}_{n}$ and $\theta_n$ in Strong gravitational lensing?

I am currently studying the strong gravitational lensing effects by general relativity. However, when studying these effects I came across several paper (especially these two papers, Paper One and ...
-1
votes
0answers
21 views

Is there anyway formula to calculate the heat produced by the burning glass and lenses?

Am just doing a simple project with burning glass. Is there any formula to find heat produced by it relating with the focal length or magnification of lens as well as mirror too?
0
votes
0answers
28 views

Minimal size of an optical lens

Is the minimal size of an optical lens (diameter, width and curvature) limited by the wavelength of the incident light?
-1
votes
0answers
17 views

Alternate derivation of the Thin Lens equation

Is there another, fairly straightforward way to derive the Thin Lens equation without using similarity of triangles?
1
vote
1answer
42 views

Why does length of objects seem different in different configurations of object and observer?

Today, I had gone to my friend’s garden. There was a dried water well in his garden. We got curious that know how much its depth is. First, we stood on top of the well and estimated its depth. We ...
40
votes
5answers
5k views

If a lens focuses all incoming light to a point, how do we get 2D images?

How do lenses produce 2-dimensional images, if a lens bends all incoming rays of light to intersect at the focal point? Shouldn't this produce a single dot of light on a screen placed at the focal ...
1
vote
0answers
56 views

How was microscope-level zoom created by a lens and a water droplet?

It was a rainy night. My glasses were speckled with fresh water droplets. I looked at a distant street light and I was surprised to see cells - a single cell was zoomed in to the level where I could ...
30
votes
6answers
15k views

Why does wet skin sunburn faster?

There is a popular belief that wet skin burns or tans faster. However, I've never heard a believable explanation of why this happens. The best explanation I've heard is that the water droplets on the ...
0
votes
0answers
15 views

opaque to transparent based on distance of object?

If we look through a transparent glass window of an apartment, from a distance in day light, we can’t see what or who is inside. All the light is reflected off the surface of the transparent glass ...
3
votes
2answers
4k views

Radius of curvature and focal length

Is the radius of curvature of a convex or concave lens longer than the focal length of the lens? Does the center or curvature affect the focal point in a lens?
0
votes
0answers
27 views

Double Fraunhofer , Fourier transform to the image plane?

Consider the diagram below: I know that from Franhofer diffraction we have: $$u_f(x_f)\propto \int u_o(x_o) e^{-k\frac{x_f}{f}x_o} dx_o$$ Assuming small angles. I also know that $u_i(x_i)$ is ...
1
vote
2answers
53 views

Lensmaker's equation and Imaging properties

In the textbook, usually the following construction (see the figure below) is used to determine the relative size of the image and the object. I understand that a ray parallel to the optical axis ...
0
votes
0answers
17 views

Broad Spectrum Contact Lenses - How Soon?

Given the amazing advances in metamaterials, how soon will we have the means to view a broad spectrum of electromagnetic radiation (IR through UV) by having it faithfully compressed into the range of ...
0
votes
1answer
25 views

How thin lens model work when there are two images with different distances from the lens?

I am trying to understand how thin lens camera work. From what I understand of thins lens model, the image is formed on image plane that obey the equation $$\frac1S_1 + \frac1S_2 = \frac1f$$ So ...
1
vote
1answer
43 views

What is a good book to self-teach optics?

I'm interested in camera lenses and how things like barrel distortion and lens flare happens, but know that one cannot just start there. I'm a math major and I've worked out of Strauss PDE book so I ...
2
votes
0answers
26 views

Optical bandpass filter at focal point of lens

Optical bandpass filters are designed for a particular angle of incidence (AOI), e.g. see Fig 4 here. However that is for the ray picture of light. Imagine I have a thin bandpass filter positioned ...
0
votes
0answers
10 views

Coordinate Equation of a curve which bends all the parallel incoming rays from infinity towards a single point

How should i proceed on to find the coordinate equation of a curve such that it bends all the parallel rays coming from infinity towards a single point. Yes I know that it would be a 2nd degree ...
3
votes
1answer
44 views

Relationship between angular magnification and how much bigger the image appears

How is the angular magnification of a magnifying glass related with how much bigger the image appears to the user? Is it simply the same? If yes, why? (Let's assume that the object is placed in the ...
0
votes
1answer
23 views

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 ...
1
vote
1answer
40 views

If I placed a converging lens in water, would its surface power change?

If I placed a converging lens in water, would its surface power change ? The first case when the lens is in air then placed in water; does the surface power change or remain the same?
0
votes
0answers
39 views

Sun light collimation

Is it possible to make sun light collimated in such a way, to increase energy density and keep it more less parallel? like on the Earth we have intensity of sun approximately 1300 watt/m2. If we use ...
0
votes
1answer
36 views

Calculating f-stop with given focal length and desired depth of field?

I have a varifocal zoom lens set to a desired focal length and at known distance from the subject. I also have a desired depth of field. Given this information, can I calculate a theoretical f-number ...
0
votes
0answers
20 views

addition of two lenses with a finite separation in between

Suppose there are two lenses with focal length $f_1$ and $f_2$ respectively. The effective focal length $f$ when they are combined is $1/f=1/f_1+1/f_2$, but this formula assumes the separation between ...
1
vote
1answer
50 views

What are the right signs? [closed]

This is a question provided in my book: An object of height $2\ \mathrm{cm}$ is placed at a distance of $2.5f$ from a concave mirror where $f$ is the focal length. Find the height of the image. ...
2
votes
0answers
62 views

Breakdown of Snell [closed]

I have reason to believe the following: If we are using an accurately formed thin prism, with an apical angle of let's say 2 degrees, and direct a monochromatic source beam thru a slit onto the ...
0
votes
0answers
15 views

Focal length value for infrared camera

I always thought that the 5 mega pixel camera attached to my Android tablet wasn't worthy of seeing the infrared. But I was wrong! The infrared led protruding from my circuit happily shows up it's ...
0
votes
1answer
51 views

Calculating the diameter of Jupiter through an image

I took an image of Jupiter through my 8" Dobsonian Telescope, attaching a DSLR and a 1.25" Barlow Lens where the eyepiece goes, as shown in this video: https://www.youtube.com/watch?v=reFxoF3XoaU ...
4
votes
3answers
146 views

Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?

Why does a laser pointer contain a laser diode, and not just an LED? A laser pointer contains a laser diode, which essentially shines coherent light over a large angle, and a collimating lens, to ...
1
vote
2answers
83 views

How come lenses alter the path of photons?

From what I know, photons are theorized particles and believed to be massless (just energy) and travel at the speed of light. How come a lens, which is an object made of atoms, can bend a light path? ...
2
votes
1answer
42 views

Does curving only the inner surface of a diving mask prevent blurred images?

Diving masks often have lenses built into the glass for divers who do not have perfect vision. The lenses in a diving mask faceplate often only have a curved surfaces on the inside glass. Why is this ...
2
votes
0answers
27 views

What is the relative importance of lens element quality in a multiple lens system? [closed]

I tried grinding a custom lens out of acrylic glass (diameter 20mm, focal length 30mm). Not very surprisingly, the result is a quite poor quality lens. I think it mostly suffers from geometry and ...
3
votes
2answers
59 views

Optics to correct focal distance across a plane

I have a laser beam which is focused to a point at a certain distance. I'm then going to use a galvanometer to scan that beam across a plane. Obviously, as the beam scans across the plane, the ...
-2
votes
1answer
44 views

Tricky Optics Questions, shifting lenses [closed]

A candle is placed at a fixed distance in front of a wall. A lens is inserted and moved slowly between them. At two particular positions, sharp images are formed on the wall. The heights of the images ...
0
votes
0answers
9 views

Why do Photochromatic lenses react to temperature changes?

So, I'm aware that Photochromatic lenses are affected differently due to different ambient temperatures. From what I've read it seems that the molecules rearrange their structures slowly in cold ...
3
votes
0answers
32 views

Where do rays that are not marginal or principal get stopped?

The picture is from an MIT lecture but the concepts are explained in many optical texts. The chief/principal rays go through the center of the aperture stop, hit the edge of the field stop, and the ...
0
votes
2answers
114 views

How is focal length defined for a two lens system?

I have found the formula for the effective focal length $f$ of two thin lenses with focal lengths $f_1$ and $f_2$ separated by distance $d$ to be $\frac 1f=\frac 1{f_1}+\frac 1{f_2}-\frac d{f_1f_2}$. ...
0
votes
2answers
509 views

Rule sign for concave and convex lens?

I am just totally confused about the rule sign of convex and concave lenses. The general formula: $1/v-1/u=1/f$ Is okay but when solving problem sums sometimes $v$ becomes negative sometimes $u$ and ...
4
votes
3answers
4k views

How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?

I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm. I ...
2
votes
2answers
114 views

Why do you need at least two rays to form an image?

Why isn't enough one light beam to form an image in your retina for example?
1
vote
2answers
47 views

Covering half of a lens [duplicate]

What happens to the image of an object kept before a lens if the upper half of lens is covered by an opaque coating? I understand that the full image will be formed and only the intensity of the ...
0
votes
0answers
35 views

Splitting an image in a lens into two sources?

Is it possible to project an image of light that passes into a lens onto two surfaces without affecting the image?
1
vote
2answers
88 views

view angle independant focal point

Is there any way to design a lens or system of lenses where I see the same part of the image below the lens, irrespective of direction from where I am viewing. In the image uploaded, there is a black ...
1
vote
2answers
83 views

Convex lens with object at the focus

When the object is at the focus, the image will be formed at infinity. What exactly does this mean? What will it look like if you hold the entire apparatus at arms length? Will it be extremely blurry?...