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1
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0answers
39 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
94 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
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0answers
69 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
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0answers
43 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
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1answer
73 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
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2answers
72 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
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. ...
0
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1answer
22 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
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1answer
112 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
156 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
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0answers
38 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
134 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 ...
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 ...
0
votes
1answer
127 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 ...
0
votes
0answers
30 views

Effect of introducing lens on Fringe width

Suppose I have a light source of wavelength 400 nm. The slits are placed at a distance 1 mm apart. The distance between the slit plane and the screen is 50 cm. So that makes the fringe width, $\beta ...
1
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1answer
75 views

Calculating lens parameters

I have a very bright LED light and I'd like to make this light focus so it forms around 5mm thick strong line (height can be arbitrary) on on an object about 150 mm away. I used a cylindrical lens ...
0
votes
1answer
57 views

Combined function magnet

I am searching how a combined function magnet for accelerator physics works, but on the books that i have and on the web i can find only patents for this thing, that suppose to know already how this ...
1
vote
1answer
866 views

Difference between convexo-concave and concavo-convex lenses?

What is the difference between concavo-convex and convexo-concave lenses? We dont say convexo-plane for plano-convex. Does that mean concavo-convex and convexo-concave are essentially the same?
3
votes
1answer
62 views

Easy method to measure the NA of a lens system?

I have a lens system made up of some components of the Leica Z16 APO zoom system. This includes a built-in iris diaphragm to adjust the Numerical Aperture (NA) and therefore the depth-of-field (DOF). ...
0
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1answer
73 views

Optics - how a lens distorts the image

If we consider a small object of length $b$ that is placed flat along the axis of a concave mirror, how will the image produced be different from the object? I know that a lens will magnify or ...
0
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2answers
85 views

Is it possible for two strong lenses to cancel each other effects?

Is it possible for a lens system for 2 strong lenses to cancel each other, so it looks almost the same as a common glass, while at the same time making an object in between them appear big and ...
0
votes
0answers
23 views

Shaving down length of a GRIN lens to a desired wavelength

I have a GRIN lens that collimates light from a point source at 670nm. I want to shave the thickness of the lens down to use for 530 nm. I can't find anything useful for equations online. None seem to ...
0
votes
2answers
394 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 ...
0
votes
2answers
165 views

Which one is better 40'' parabolic mirror or 34''x44'' fresnel lens?

I want to make solar concentrator which can reach 2000F or above temperature at focussed spot, so I came across parabolic mirror and fresnel lens but I can't decide which one is better. Also I will be ...
2
votes
2answers
230 views

Cause of Spherical Aberrations

What is the cause of spherical aberrations in lenses? I know that it's due to the differing width of the lens, but I don't understand/know the physics of why the lens width affects the focal distance ...
0
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0answers
114 views

Why Double Fresnel Lenses on HMD

I'm creating my own HMD (head-mounted-display), and I saw that nowadays, Double Fresnel Lenses are used for the "Wearality" (HMD, see link below) with a lot of success (I read somewhere that the HMD ...
-1
votes
1answer
71 views

Designing a lens

What factors would I have to take into account when designing a lens. For instance, I want to design a lens that has a focal length of approximately 20 cm, and it is intended to be used for ...
0
votes
2answers
103 views

Image formation by a convex lens without a screen

The real image of an object placed between f and 2f from a convex lens can be seen on a screen placed at the image location. If the screen is removed, would the image be still perceived? Is the image ...
1
vote
1answer
78 views

How can the active area of a photodiode increased?

I use photo-diode VTB8440BH. To increase its active area I was thinking to put a lens in front the diode would enlarge its active area. What kind of lens would be beneficial one? I was thinking of a ...
2
votes
1answer
67 views

How to transmit light ideally through not parallel tiny holes within a metal case?

I currently try to transmit light through a tiny hole of one side of a metal case in order to receive the light on the other side of the case. The tiny holes are not parallel (see image 2). Using ...
0
votes
1answer
235 views

How to calculate the diameter of a thin lense?

A photo produced with a single thin lense is provided. Only based on the photo I should calculate the diameter of the lense. The photo shows a ruler in the foreground and a point source of light in ...
2
votes
1answer
107 views

How does light focused through a lens create bokeh (blurry background)?

This question is relevant, though I don't think it quite answers the question. From a photography perspective, when you open the aperture wide (with a small f-number) you get a very shallow depth of ...
1
vote
1answer
148 views

Spherical and chromatic aberration correction

I have some spherical lenses which are 5mm, 1mm and 0,5 mm in diameter, having 100x, 350x and 1000x magnification respectively. While looking at blood samples, I'm having big problems with spherical ...
0
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0answers
36 views

Singular isothermal density distribution

Does anyone know where the Singular isothermal density distribution $$ \rho(r)=\frac{\sigma_{V}^{2}}{2\pi\,G\,r^{2}} $$ or how it was derived. Are there any good references on how this equation was ...
1
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2answers
206 views

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions?

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions? I'm thinking about the scenario where someone is holding a smartphone ...
0
votes
0answers
34 views

Why do acoustic lenses need air channels?

In every design of an acoustic lens I have seen so far, be it Fresnel lens or GRIN lens, there are always air channels included in the design. I don't see why this is needed. Couldn't a lens be built ...
39
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
2answers
102 views

How can one prove the equation for a system of lenses? [closed]

Let's say we have a system of 2 lenses which are placed in a non-negligible distance $L$ from eachother. How can I prove without using geometrical construction and principal planes that $$\frac 1f ...
1
vote
1answer
696 views

Question about lens maker's formula

I am trying to follow the derivation of lens maker's formula from the textbook "University Physics", p.1133 ...
2
votes
0answers
169 views

General proof of formulas of geometric optics?

In most lf textbooks formulas of geometric optics like lens maker formula and base formula for that are proven (or rather verified from my point of view) by taking specific case (ray diagram) and ...
0
votes
0answers
180 views

Is the human eye diffraction limited, or is there another limiting factor?

I know that most problems involving the human eye in my undergrad physics text book tell the student to treat the human eye as a diffraction limited system (ie to assume the only factor limiting human ...
1
vote
0answers
27 views

Imaging and the Electric Field

In this book (pg. 162), it mentioned that conventional lenses only focus propagating waves, thereby creating an imperfect image. In contrast, superlenses focus both propagating and evanescent waves, ...
1
vote
0answers
54 views

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 ...
0
votes
1answer
208 views

Size of object from its image [duplicate]

If the quality of the camera (i.e. the megapixels) (assume to be $x$) of the camera is known and an object is kept a known distance from the camera (assume to be $d$), can the actual width and length ...
1
vote
0answers
23 views

Spherical Aberration Of Electron Lenses

I would like to know why electron lenses can't have negative spherical aberration. Every textbook I have found devotes one or two sentences to saying that Otto Scherzer prooved this 80 years ago, but ...
-2
votes
1answer
153 views

What wavelength of light is the term 'focal length' defined against? [closed]

Because different wavelengths of light are bent differently in a medium, the focal length ought to be different for each of them (which is why white light splits up into a rainbow). If I have a "25 mm ...
2
votes
1answer
238 views

If I wear contact lens and spectacles of same power, is it same wearing thick spectacles of twice the lens power?

Assume I have a contact lens of power -1 and a spectacles of +1. Will they cancel out their effect? is it same as my normal eye sight?
0
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1answer
149 views

Combination of two concave lenses

When we have two convex lenses in contact we have the combination behaving as a converging lens. Can someone please give an analytical description for the combination of two concave lenses in contact ...
0
votes
2answers
549 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 ...
0
votes
1answer
257 views

combination of mirror and lens [closed]

a convex lens forms a real image of a point object at a distance of 50 cm from convex lens. a concave lens is placed 10 cm behind convex lens on image side. on placing a plane mirror on the image side ...