Questions tagged [lenses]

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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
31 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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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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20 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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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
32 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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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
29 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
28 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
22 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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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
43 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
32 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
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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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1answer
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In double slit diffraction, why does the intensity profile not change w.r.t. distance from the slit if is a collimating lens fixed in between them?

As far as I know, with respect to double slit interference, the distance $y_m$ measured along the screen from the central point to the m-th bright fringe is related to the distance $L$ from the slits ...
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1answer
89 views

If photon is is emitted in random direction then how does a lens work?

If the absorbed and then emitted photon is a radial wave that later collapses to a random direction (when measured / received) then how does an optical lens work? Can you explain in layman terms (...
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1answer
33 views

What is aperture of a lens?

I read that aperture of a lens is the surface from which refraction takes place and it is represented by the diameter of the lens. So, by saying that the aperture refers to the surface from which ...
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2answers
26 views

Real versus Virtual images: Multi-Lens systems

So I am confused about whether the final image produced by a multi-lens system is virtual or real. Is it just if that if the final image has light rays converging to that point then its real? or is ...
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19 views

Magnification factor point mass gravitational lens

I am doing a project on Gravitational Lensing, and I'm trying to work out how a point-mass lens changes images. To calculate the magnification factor of a point-mass lens, you have to fill in the ...
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1answer
41 views

Why does convex lens diameter affect its magnification?

Usually , reflector telescopes will have a greater angular magnification because the focal length can be increased in the same physical distance, so to achieve the same angular magnification, ...
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3answers
52 views

Why do refracting telescopes have a wider field of view than reflecting telescopes?

Many websites say refracting telescopes have a wider field of view than reflecting telescopes, claiming it is because their angular magnification is less. Astronomical objects are therefore easier to ...
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1answer
29 views

Modelling of lenses with arbitrary concentric phase grating in Zemax

I develop multifocal hybrid lenses that can be modelled as concentric phase gratings superpositioned onto a normal refractive lens body. These type of lenses are commonly used for multifocal ...
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1answer
74 views

Why does the focusing efficiency drop with numerical aperture for a microscope objective?

I am doing the following experiment in my lab. I have a collimated laser beam, which is focused by a lens. Then the light is collected by a microscope objective. Also, I use two lenses (L1 and L2) to ...
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16 views

Does the far point change while using convex lens to correct hypermetropia?

Let use create a context first: A healthy eye has horizontal range of vision from 25 cm (near point) to ∞ (far point). A person X has myopia, so his range of vision with unaided eye will be 25 cm ...
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0answers
17 views

Field curvature: why is it a third order aberration?

I am trying to understand the different kinds of aberrations that exist with rotationally symmetrical optical system, as a simple lens for example. What I have learnt so far (correct me if I'm wrong):...
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24 views

Images formed due to lens made of 2 different materials

The lens is made of 2 different materials, and we can conclude from the given diagram that the materials of refractive index u1 are symmetrically placed with respect to the principal axis of lens.My ...
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1answer
19 views

How to determine the focal length of a lens that is equivalent to two lenses?

For context on this question, I've included a whole diagram explaining the situation: I have a light bulb with a 10° spread that I want to narrow down into a beam and send through a diffraction ...
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4answers
4k views

How does a telescope make an image larger by shrinking it?

I saw these images of how a telescope works and it seems like it is shrinking the image down to the size of the eye. I don’t understand how that makes the image bigger. My thinking is that shrinking ...
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1answer
50 views

Chromatic aberration in lenses

We all know that concave lenses act as diverging lenses, but while searching for remedies for chromatic aberration, I observed a concave lens (in the picture see flint glass) acting as a converging ...
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1answer
78 views

Explaining why rubbing two surfaces together by hand create convex and concave shapes?

From this video (relevant timestamp included in URL): https://www.youtube.com/watch?time_continue=768&v=ABRysNzcdvw&feature=emb_title It shows how rubbing two surfaces together by hand with ...
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0answers
37 views

Working of corrective lenses

I was reading about vision defects like myopia and hypermetropia . In one question it was asked whether the corrective lenses change the size of the object or not. I think it should change the size ...
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2answers
29 views

Sharpen reflected image

I'm currently working on a project which is a kind of hologram. As an object I have a display and with a plexiglass I use the reflection so that I can see the display inside the plexiglass. The ...
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2answers
26 views

Is there a lens system that captures paraxial parallel light and turn it to a certain direction?

To turn arbitrary parallel light into a designated direction, one can make use of a flat mirror and an electric motor that turns it to a desired direction. I would like to know if this can be ...
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1answer
36 views

Two positions of the convex lens for a fixed object-screen separation

Explain why, for a fixed separation between the object and the screen(i.e., d + d' is fixed) there are two positions of the lens at which the images formed on the screen are in focus (clear images or ...
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21 views

Can a good photographic objective be much thinner than wide?

Modern photographic objectives are made of multiple lenses with constant refractive index in each. The result is that thickness of an objective is comparable to (and sometimes even larger than) its ...
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3answers
87 views

How to think about virtual images?

I have been messing around with magnifying glasses recently and I am stuck on a simple concept. From the thin lens equation we know that $$\frac{1}{s_0}+\frac{1}{s_i}=\frac{1}{f},$$ with the sign ...
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1answer
49 views

How to graphically determine equivalent focal length of two thin lenses?

Suppose we have the schematic above. The first lens has a focal length of 80mm and the second one has a focal length of 60mm, and both are biconvex. My job is to determine, graphically the equivalent ...
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How to use convex lens to magnify image without inverting

From my knowledge, convex lenses magnify and invert light rays that pass through it. So is it possible to use a second convex lens to make the magnified inverted image into a magnified upright image?
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2answers
56 views

Is it possible to use fresnel lens(es) to focus an LED light on a headlamp

I was hoping that someone would be willing to offer any insight or guidance they have on a project that I am working on. We are trying to use a lens mounted on a headlamp to focus a plain white light ...
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1answer
29 views

Dependence of the focal length of converging lenses on the absolute index of refraction

How will the focal length of a converging lens change if it is replaced by one having a greater absolute index of refraction?
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Helmholtz's Equation in Geometrical Optics

As in BSc. Physics Course, I read about the Helmholtz's equation which is as follows, $$n_1h_1\tan(\theta_1) = n_2h_2\tan(\theta_2) = H$$ in geometrical optics in the thick lens combination. Here $...
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1answer
20 views

Requirements for rays to converge exactly at a point $P'$

I am currently studying Modern Optical Engineering, fourth edition, by Warren Smith. The textbook says the following: In Fig. 1.10 several ray paths have been drawn for the case of a converging ...
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1answer
47 views

What happens when a mirror is placed before a concave lens?

Recently i saw a video on YouTube where someone made a data glass which uses convex lens, from what i know convex lens create virtual image when the object distance is shorter than the focal length, i ...
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Large Electromagnetic Lens to Focus Cosmic Rays

Is it feasible to build an electromagnetic lens (such as but not limited to a toroidal wound solenoid) of large area (perhaps as large as the ring at the supercollider at CERN) to focus and intensify ...
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18 views

Simple microscope but tangling doubt!

My textbook (NCERT optics Class 12 pg 339) on simple convex lens microscope says, The idea is to get an erect, magnified and virtual image of the object at a distance so that it can be viewed ...
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1answer
29 views

How does a convex lens produce an image at a distance?

What exactly is going on in this ray diagram? If the object AB is placed between the focal point and center of the lens, then how does the image A'B' form at a distance? Where is the light being ...
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0answers
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Designing eye-glasses with a small magnification and fixed focal distance?

Is it possible to design eye glasses that sit 2 cm from the eye such that an object of height $h_o$ and distance 20 m is magnified to a height $h_i = 1.2 \cdot h_o$? How complex would such a system be?...
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2answers
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Convex spectacles lens isn't forming inverted image?

I moved my spectacles of farsightedness away from an object and tried to look at the image formed. It was erect. I moved even more far but still it was erect. How is this possible? I hope my ...
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1answer
72 views

Why is there no refraction of light when it passes through a semi circular surface but refraction takes place at the surface of a convex lens [closed]

A convex lens has a curved surface just like that of a semi circular block. When light passes through the curved surfce of the semicircular block it doesnt refract. But when light does it refracts ...
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1answer
38 views

Why my myopia spectacles doesn't allow a person with normal eye to see clearly?

I am a student of class 10. I have been taught that myopia spectacles (concave lenses) corrects the vision by forming a virtual object at the person's far point. But I am unable to figure out one ...

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