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0
votes
1answer
18 views

How do you calculate the change in location of the focal point by rotating the lense? [on hold]

Image you have a lens with a certain focal length. Light will be focused into the focal plane on the Optical Axis if the light is a collimated beam which travels parallel to the Optical Axis. But I ...
0
votes
1answer
30 views

How image is formed within the eye? [on hold]

So our eye has a layer of nerves. Our eye lens refracts and concentrates light rays of different amplitudes, and that concentrated impulse (of a mixed amplitude) induces a signal on some nerve; since ...
0
votes
1answer
120 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
votes
0answers
15 views

PSD image detection [on hold]

A laser is pointed on a surface, such that it is reflected onto a PSD (position sensing photodiode). Before light reaches the PSD, it goes through a plano-convex lens to get focused. Now, if the ...
2
votes
0answers
43 views

Breakdown of Snell [on hold]

I have reason to believe that if we are using an accurately formed thin prism, then very near the working apex, where there are few atomic layers in a latticed prism, there will be inaccuracies in the ...
0
votes
1answer
32 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
101 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
79 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
39 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
19 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
50 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 ...
0
votes
2answers
506 views

How to use a magnifying glas 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 ...
-2
votes
1answer
30 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
7 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 ...
2
votes
2answers
3k 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?
3
votes
0answers
21 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
66 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
334 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
96 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
43 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
32 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
80 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
55 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 ...
2
votes
0answers
50 views

Lenses that pixeliate incoming light [closed]

Is it possible to make a lens that 'pixelates' the light passing through it? I imagine a pair of glasses, that when put on, turn the world into a grid of discrete pixels, each having, or appearing to ...
0
votes
1answer
31 views

combination of lenses for undefined focal length

Good morning! I am not an optics specialist, but I need to know if it's possible to do what I tried to visualise in my picture. Basicly I want to merge two beams into one. I am thinking of using a ...
1
vote
1answer
50 views

Why does a specific static image “move” when moving my head? (glass user)

I am a daily PC user. As most users, I have a taskbar (using Windows) that shows icons of programs. My two screens are big (24") and I'm at ~60cm distance from them, so fairly often I need to turn my ...
0
votes
0answers
22 views

How to determine the distance between the principal planes?

How to determine the distance between the principal planes ? If you know the lentgh of both focii, $\overline{FH}$, $\overline{F'H'}$ and additionally the distances $\overline{E1H}, ...
1
vote
2answers
29 views

Focus correcting screen [closed]

With the rapid approach of VR, and being someone who's always needed glasses! I have been curious about this for a while. Is it possible to correct the focus of a lens by adjusting the image on a ...
0
votes
2answers
54 views

Is there any limit to distance between two waves when used in Huygens principle?

Apologising for not being clear. When I used Huygens principle to determine the spherical wavuefront of radius $R/2$ created by reflection from a spherical concave lens of radius $R$, I got amazingly ...
2
votes
3answers
1k views

Newton's rings experiment

I have performed experiments in my college laboratory on Newton's rings to find radius the of curvature of the convex lens used. I always get a dark center. Is it possible to get a bright center? If ...
1
vote
1answer
26 views

How does magnification work in lensless optical setups?

In my optics classes, I have only ever seen magnification defined in conjunction with the thin lens equation. However, in a lensless optical setup such as lensfree in-line holography, how does one ...
0
votes
1answer
22 views

How lens for specs are manufactured for a given power? Do thickness, refractive index play role? [closed]

I read some where that if the prescribed glass power is more, glass must be made of higher refractive index to lessen the thickness. But from knowledge of physics, power just depends on focal ...
2
votes
2answers
35 views

Diameter of a lens vs Diameter of the circular Aperture of the lens vs Aperture of the lens

I was reading about resolving power in which it is said that "a is the diameter of the circular aperture or the diameter of the lens, whichever is smaller" . So, I don't understand how are they not ...
26
votes
3answers
147k views

Virtual vs Real image

I'm doing magnification and lens in class currently, and I really don't get why virtual and real images are called what they are. A virtual image occurs the object is less than the focal length of ...
1
vote
2answers
68 views

What is exactly an ‘virtual object’ ? ( From the point of view of lens maker’s formula )

Here’s an image from my textbook It shows, how an image is obtained from a convex lens. The second and the third images, shows in depth , that how a convex lens behaves. They say, that suppose ...
1
vote
1answer
38 views

Deep confusion with conventions and signs in geometric optics

This is an equation given in my book. The question is why have they used a negative sign on the LHS? Now, if you try to derive the mirror equation with simple geometry, you get 1/v +1/u =1/f . ...
2
votes
3answers
4k views

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 ...
3
votes
1answer
36 views

Concave lens path of ray

What will be the path of ray passing through the first focal length of a biconcave thin lens kept in air? I know that a ray passing through focus or appearing to pass through focus of a thin lens ...
0
votes
2answers
50 views

How does the distance between a light source and a lens affect the beam's intensity?

I have a system with a light source, a convex lens, and a light detector. The beam travels from the light source, through the lens (causing a divergence), and into the light detector. The light source ...
5
votes
1answer
67 views

Strength of moonlight

So I read this xkcd, and thought it was kind of cool. However, I showed it to my engineer father and physics undergrad brother and neither seem to find the explanation very convincing (though they ...
2
votes
2answers
52 views

Why don't eye lenses alter depth perception?

What it is going to do is bend the rays so that light from infinity "appears" as though it is coinciding with a person's far point. In doing so, it allows the person to see a clear image, without ...
4
votes
2answers
4k views

Why do focal lengths affect magnification?

For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens. In telescopes, the objective lens projects an image on its focal point which works as the object ...
1
vote
2answers
401 views

Ideal distance of eye from a lens

I observed that when I keep constant distance between object and lens but I move my eye, I get different magnification. When I am closer to lens I can see large image of the object. But if I go away ...
1
vote
1answer
68 views

When is a negative focal length used in optics?

I'm getting confused with conventions. I was wondering if this logic is correct: If an image appears on the same side of an object, then we use a negative focal length for determining information ...
1
vote
0answers
22 views

influence of soft iron in magnetic lenses

I'm currently working as an intern in a research group which is specialized in transmission electron microscopes. I'm reading a book from David B. Williams and C. Barry Carter : Transmission electron ...
0
votes
2answers
70 views

Can light be rotated using lenses or prisms?

I was wondering if it was possible, by using only lenses, mirrors, or prisms, to rotate a ray of light coming from a certain direction. For example, if I have two lasers beams side by side, is it ...
2
votes
1answer
52 views

Why does this illumination pattern of an LED light going through a small pinhole not emulate the point spread function?

I have an optical setup where a component LED passes through a 50 um pinhole, and creates an illumination pattern on an image sensor approximately 5 cm away that looks like the following: Now, I'm ...
41
votes
6answers
5k views

Do people wearing glasses have different field of view than those who don't?

There is one thing I sometimes wonder about ever since I was a child. Do people who wear eye glasses see objects in different size than those who don't?(Technically different size means different ...
2
votes
1answer
78 views

How to determine the radius of curvature of a convex lens?

Suppose there is an equi-convex lens made of glass which has a focal length ($f$) of 30cm. Then, can we not say that the radius of curvature, $R$ of the lens is twice the focal length, i.e. $R = ...