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0
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1answer
27 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 ...
3
votes
3answers
94 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 ...
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 ...
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
1answer
29 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 ...
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
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 ...
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 ...
1
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2answers
39 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
2answers
64 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
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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
53 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 ...
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 ...
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 ...
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 ...
1
vote
2answers
67 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 ...
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 ...
1
vote
1answer
37 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 . ...
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 ...
1
vote
2answers
78 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? ...
0
votes
2answers
49 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
65 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
51 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 ...
2
votes
2answers
95 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
1answer
64 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
69 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
51 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 ...
2
votes
1answer
76 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 = ...
1
vote
1answer
139 views

Stacking lenses for higher magnification (a DIY microscope)

Recently, I have made a DIY microscope stand for my phone according to these specifications. I am using a lens that I found in home, the closest match that I could find is here. I got some great ...
0
votes
0answers
16 views

The image of an object through a curved surface

We have a curved surface, separating two different medium, with refractive index n1 and n2. We know the radius R of the curve,then how can we find the position v of the image? I read that the ...
1
vote
0answers
28 views

The sign of a focal length

We know that for converging lens, $f>0$ , for diverging lens, $f<0$. But for many materials I have read so far, it says that: "the focal length of a concave lens is 8 cm." I thought that the ...
41
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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 ...
1
vote
0answers
38 views

Given a focal length and an aperture of the telescope, what is its field of view?

While I know FOV of scope is equal to FOV of eyepiece divided by magnification. How can one find FOV given only the focal length and aperture of the telescope?
0
votes
1answer
79 views

The confusion of fractional error calculation

I need to find the focal length of a lens by using equation 1/u + 1/v=1/f I have: u= 50+-3 mm v= 200+-5 mm I calculate the value of f as 40mm. Now i need to find the uncertainty in this value. ...
0
votes
0answers
64 views

Lens formula and Lens maker's formula

When we derive the formula for lens and lens maker's formula using the formula for refraction at spherical interface $$\mu_2/v - \mu_1/u = (\mu_2-\mu_1)/R$$ we put $u$ to be $-u$ as it is on the left ...
1
vote
0answers
38 views

What happens when there is object exactly in the focus of converging lens? [closed]

I was learning some optics and then I wondered what would happen if some object was exactly in the focus of converging lens, more accurately, what would I see if looking from the other side? EDIT: so ...
0
votes
1answer
65 views

Lens combination

Suppose there are two lenses touching each other as shown in the diagram below. the focal length of the lenses are $f_1$ and $f_2$ respectively. Now by using the formula for lens combination I ...
1
vote
2answers
71 views

Can lens designs be brute-force computed to create optically precise equipment? [closed]

It seems lens design hasn't changed much over the last 50 years or so with many older manual lenses still very much being used today. Can the order, distance between and type of lens elements be brute ...
1
vote
0answers
29 views

What is the maximum concentration ratio achieved for CPV (concentrated photovoltaic)? [closed]

CPV uses ratios in the range of 100-1000. On what lens parameters does it depend.
0
votes
1answer
20 views

What parameters decide the maximum concentration achieved by a fresnel lens?

Fresnel lens can be used for concentrating sunlight for Photovoltaic. What parameters of the lens decide the maximum concentration that can be achieved using the lens.
0
votes
1answer
91 views

Does 'focal length' mean something different with lenses and pinhole cameras?

Sometimes different but related things have the same name by some tradition or accident, causing a lot of headache to newcomers to a field. I would like to come to clear terms with this: does the ...
2
votes
2answers
148 views

Experiment to find the circle of least confusion (optics)

I want to conduct an experiment where the circle of least confusion (wiki ref) occurs for a lens. Suppose that I shine white light onto the lens and I know the lens EFL is lets say 100 mm, in order to ...
0
votes
0answers
36 views

Balance lens tilt aberration

Given a doublet (singlet in reference figure), if the rays enter at an angle with respect to the origin axis, we would see a shift of focal length for blue and red. A known optical jitter How could ...
-3
votes
1answer
106 views

Combination of mirror and lenses [closed]

I am a keen learner of physics, but I am unable to solve problems involving lenses and mirrors together. please can anybody tell me the method to solve these problems? for instance let us take a ...