Questions tagged [lenses]

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40 views

It is harmful to look directly towards the Sun. Why? [closed]

Sun's electromagnetic spectrum, Convex lens of the eye, Retina.
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1answer
40 views

What is the proof that we can use virtual object to know the place of formation of image in case of convex/concave lens?

What is the proof that we can use the location of virtual image in the lens formula to get the location of the image (convex/concave lens)? The following problem might make my question more clear. The ...
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3answers
21 views

Focal Length as it relates to Field of View

I understand that in physics, for a converging lens, the focal length is based on the refractive index of the lens material and its curvature. However, I started reading a bunch of photography ...
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1answer
44 views

How do fundamentally electrostatic lenses work?

I don't need any super specific answers. But I would it appreciate alot if someone could either confirm or correct my thought process. I know that for many of you this will sound super obvious but for ...
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0answers
13 views

Explain the formula of $P =1/f $ for mirrors [duplicate]

Using magnification formula for mirrors $m = f/f-u$. This gives $m$ is linearly proportional to focal length. So, how do we intuitively understand power of a mirror?
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1answer
19 views

How does longer length of optical path in binoculars increase its magnifying power?

I just read about Prism Binoculars from my high school physics textbook. However, I am not able to understand how does increasing the distance light travels from the objective lens to eyepiece can ...
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0answers
22 views

What's the difference between Electromagnetic lens and an Electrostatic lens?

So I've read a couple of pages and watches a few videos but at their core neither has answered this basic question. I remember from the lecture that the prof. said that one needs a high current while ...
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4answers
99 views

Does adding a supplemental lens attachment to a phone increase the megapixels it can resolve?

I am reading: https://en.wikipedia.org/wiki/Optical_resolution But am confused if adding a supplemental lens to an imaging system (in this case my phone) would change the amount of information ...
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1answer
32 views

Why do plano-convex lenses reduce spherical aberation?

I keep reading this in comparisons of different kinds of lenses but I don't understand why the flat side would change the amount of spherical aberration if the focal length still has to be the same?
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1answer
44 views

Dilemma in calculation of percentage error while measuring focal length on an optical bench

An optical bench has $1.5$ $m$ long scale having four equal divisions in each cm. While measuring the focal length of a convex lens, the lens is kept at $75$ $cm$ mark of the scale and the object pin ...
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2answers
35 views

Can microscope lenses be non-spherical?

Most lenses are spherical, but... Are there elliptical, parabolic or hyperbolic microscope lenses? (I asked a similar question, about telescopes, on Astronomy S.E.; I hope this is not considered '...
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0answers
11 views

Lens Maker equation and Geometrical equation

or a myopic swimmer with a prescription of -7.0 diopters, what should the radii of curvature of the lens surfaces be if the goggles are made from a high index plastic of n = 1.6? First, what is the ...
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0answers
26 views

What determines if light rays will be parallel to each other after refraction through a lens?

This is an example of a refracting telescope: As you can see, when passing through the eyepiece (second lens), the rays are refracted parallel to each other. Why are they refracted parallel relative ...
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0answers
24 views

Do progressive lenses consist of plateaus?

Anticipating that in the not-too-distant future progressive lenses are unavoidable, I have inquired at a store from a famed brand (LensCrafters) about the nature of these lenses. There, to explain ...
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2answers
57 views

Which path does light take through a lens?

In the picture below, the three principal light rays are drawn refracting through the lens , forming an image on the other side. But which path does the light actually take? That is , if i place my ...
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2answers
43 views

My question is about ray optics particularly image defects

I was learning about spherical abberation and in my book it is written that when parallel rays pass through lens marginal rays (which are far from principal axis) are bent more than paraxial rays(...
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2answers
44 views

Biconvex lens kept on a plane mirror

Q. A thin biconvex lens is kept on a plane mirror. When an object is kept at $20 cm$ in front of the lens, its image is formed at the same point. The focal length of the convex lens is The solution ...
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1answer
40 views

Focus at infinity

I have myopia so I wear corrective lenses. One set of glasses I have is designed to focus from about 2 feet to infinity. I can see the dashboard of a car, but I can also see buildings at long ...
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1answer
65 views

Focal length of lens combination [closed]

The adjacent figure shows a thin plano-convex lens of refractive index $μ_1$ and a thin plano-concave lens of refractive index $μ_2$, both having same radius of curvature $R$ of their curved surfaces. ...
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1answer
16 views

Validity of wave front curvature calculation for a gaussian beam depending on the focusing conditions

The curvature of a gaussian beam is usually given by $$R(z)=z\left(1+\left(\frac{z_r}{z}\right)^2\right)$$ with $z_r$ the Rayleigh length. Is there a limitation for that curvature (similar to usual ...
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0answers
42 views

Distortion of a double Gauss lens

I am working on previous exam questions from my optics course and am stuck on this short question about the distortion of a Double Gauss lens. A double Gauss photographic lens images $50^\circ \times ...
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1answer
29 views

Question about the colour of an image formed by a concave lens

I will try and describe my observations the best I can. I placed a candle in front of me and my spectacles a bit further ahead of the candle. I have negative power so my spectacles must be concave. I ...
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1answer
43 views

Problem involving lenses and mirrors [closed]

A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between the lens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image ...
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1answer
27 views

Resolving power of telescope and circular aperture

From the formula of circular aperture we get: sinθ=1.22λ/D But according to this formula, the θ is the angle on the side of the Airy disc formed. The formula for angle of resolution for a human eye ...
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1answer
91 views

How to measure the strength of a prescription eyeglass lens?

If I am to confirm that a lens has diopter +2.50, I might seek a reference lens (one that I know is +2.50) and position both away from a sheet of paper in plain sunlight, then confirm that the focal ...
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0answers
42 views

What is the combined lens formula for Effective Focal Length (EFL) when $d > f1+f2, f1,f2>0$?

I know the standard combined lens formula as: $\frac{1}{f}=\frac{1}{f1}+\frac{1}{f2}-\frac{d}{f1\cdot f2}$ But i observed that the formula is not working when d is greater than f1+f2. (also both f1 ...
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0answers
33 views

Infinity-corrected Objective Lens Microscope Design

I am totally new to optics design. I am currently trying to play around with infinity-corrected objective lens and trying to image a slide with a Basler camera. I was able to get my system working ...
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0answers
45 views

How to choose which focal length is best for a given magnification

I have a rather (hopefully) simple question about optics and the choice of a lens for a system with a given magnification factor (optics isn't quite my specialty). I have an optical system with a fix ...
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1answer
66 views

How to make this AR (Augmented Reality) optics system work? [closed]

This is what I have: but it turns out that the image is too close to the eyes (duh :D) and it hurts trying to focus on it. Usually, VR and AR headsets use some type of lens system. My only idea right ...
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0answers
13 views

Combining concave and convex lenslet arrays

If I sandwiched a thin concave lenslet array and a thin convex lenslet array as shown(lenses have same focal length, lens diameters ~50um), while looking through it, would it appear as a plain glass ...
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2answers
127 views

How to calculate spot size of a laser focused through a microscope objective

I am trying to figure out how to approximate the spot size of a laser beam that is focused using a microscope objective where the size of the laser beam is smaller than the diameter of the objective. ...
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0answers
44 views

Imaging with A Fresnel Lens

I am in need of an optics expert on imaging, and in particular a fresnel lens is being used as for an imaging device. From my understanding a condenser lens can be considered equivalent to a plano-...
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1answer
50 views

Multiple Lens System

We have studied Two lens system, I wanted to know how to formulate when there are Multiple Lenses. Like How the formula for Effective Focal length changes when there are $2$ or more lenses. For ...
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0answers
35 views

How much can you focus sunlight?

According to this, the size of the focal spot of sunlight through a lens is f/110, where f is the focal length. A 61" fresnel lens with 86 cm focal length then has a spot which is 7.8mm high, ...
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1answer
27 views

Why does taking sign convention in Ray optics generalize the formulas?

I have read a lot about why sign conventions are used in ray optics. It is because the formulas are different for different lens and object. My teacher also said that sign conventions are like the ...
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1answer
17 views

How to find the principal axis of the pieces of lens after billetsplit cutting?

I was reading about lens from a book . There I couldn't make about the principal axis for billetsplit cutting of lens . As it can be seen from the above image that two lines L1 and L2 are drawn and ...
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2answers
45 views

Image formation by convex lens

If an image of an object formed by convex lens is simply meeting of the rays of the object due to refraction,then why do we require a screen to reflect these refracted rays?If we observe the image ...
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2answers
39 views

Which of these concave lenses has a greater power

Let's say that a concave lens $A$ has a focal length of $-10$ $cm$ and another concave lens $B$ has a focal length of $-20$ $cm$ and we need to compare their powers. We know that : $$P(D) = \dfrac{1}{...
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1answer
31 views

Imaging with two lenses: what if the distance between the lenses is not 2f?

A $4F$-configuration is usually utilized for imaging with $2$ lenses. An object is placed in the focus of the first lens ($f_{1}$), then the second lens is located at a distance $f_{1}+f_{2}$ from the ...
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0answers
18 views

What shape are digital camera lenses?

I originally thought that digital camera lenses are the same shape as a magnifying glass but I saw that lenses like that are meant for our eye which has a curved detection surface and if a camera used ...
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1answer
30 views

Why do we need a lens in the delayed-choice quantum-eraser experiment of Kim?

This is the delayed-choice quantum-eraser experiment of Kim diagram described on Wikipedia https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser Why do I need a lens in front of the ...
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1answer
70 views

Rainbow Colors on a Water Droplet on a Screen

I accidentally fell a water droplet on my mobile phone's screen. But on observing closely I saw that the water droplets showed rainbow colors (the screen was mostly white). By rainbow colors I mean ...
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0answers
24 views

Parallelising light rays from a laser projector using planoconvex lens

Materials: 26mm Dia x 35.2mm FL, Grade 1, Plano-Convex Lens. PicoP laser picoprojector. The problem: I've got a question about using a lens to parallelise light rays coming from a laser projector. ...
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1answer
35 views

Do the size of the objective lens of a telescope affect the size of the field of view?

According to diagrams like this the answer is no, because every part of the objective lens gives the whole image. But when I cover part of the objective lens of my binocular, I only see part of what I ...
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2answers
47 views

How does focal length affect magnification?

My answer would be the longer the focal length, higher the magnification will be, resulting in a larger image. But in a ray diagram, how does it look? I am searching for a comparison of ray diagram ...
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1answer
63 views

Finding the Focal Length of a Thick, Plano-Convex Lens

The lens maker's formula takes into account the thickness of a lens. However, if one surface is planar, its focal length should be infinite. But that means that with the below formula, the thickness ...
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0answers
20 views

Estimating the focus plane of camera via thin lens equation [closed]

I have a camera that outputs a JSON file for every image taken. In the JSON file, I can find camera-specific and also the photo-specific acquisition parameters used. The issue is I wish to estimate ...
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1answer
44 views

Can a person with healthy eye see things clearly if he/she uses spectacles?

Let's first see the mechanism of working of concave lens for correction of myopia. If a myopic eye has a near point less than infinity say 1 meter(m) then we use a concave lens of focal length 1, so ...
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1answer
56 views

When parallel light Ray's ( not parallel to the principal axis) pass through a convex lens, where does it converge on the focal plane?

I know that the Ray's will converge at the focal plane. But how do we calculate exactly where it will strike? Is there any formula for the same?
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1answer
13 views

When given magnification alone,for an upright, virtual image, with convex lens, how can I find object distance [closed]

Formula involved in such calculations, similar examples, link associated with d question

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