Questions tagged [lenses]

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Picture of an object at $>2f$ [on hold]

I can't find a proper image to represent what I mean but I read it several times that objects are enlarged, when they are within $f$ and $2f$. Why are they getting smaller afterwards?
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1answer
34 views

Linearizing Equations (Question given below): [on hold]

This question is mainly asking to rewrite a different graph equation (maybe parabolic, curved, etc) and changing it to a normal linear equation in the form y = mx+b. The question 5 and 6 can be seen ...
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1answer
38 views

Image formation of object on itself by a system of a lens and a mirror

Suppose there is a lens and a mirror. An object is placed in front of this system (nearer to the lens). If the final image of object (refraction, reflection and again refraction) is formed on the ...
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1answer
80 views

What would a lens-less world look like to us? [closed]

The images we perceive through our eyes are formed by focusing the incoming light with the eye's cornea and lens. The information is "captured" by the retina and then transmitted to our brains through ...
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35 views

Problem related to combination of lens & equivalent focal length and lens maker's formula [closed]

in between two equiconvex lens( made of glass) of focal length of 20cm there is a layer of water which also acts as a convex lens.The whole figure is surrounded by air. Find out it's equivalent focal ...
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1answer
21 views

Overall power/focal length of an eye and corrective lens system

Hey. I got this question wrong and I don’t get the explanation. I know that to fix myopia you need a concave lens to diverge the light rays so that the eye lens converges them further back on the ...
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1answer
46 views

How do I explain the below phenomenon I am seeing along the edges of my eyeglass lenses?

I am near-sighted. Here is the phenomenon: I stand in front of a light source that is situated on the ceiling so that it reflects off my eyeglass lenses and appears circular. It is a white light ...
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1answer
27 views

Formula for blurring out a grid of holes

Place a camera lens with focal length f_l mm and camera sensor size w mm and h mm behind an ...
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0answers
25 views

Thin Lens Approximation [duplicate]

Why is ray travelling through pole passes undeviated?( not changing any direction) ( this was asked in kvpy interview)
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1answer
37 views

If I have an IR source, would glass lenses work in focusing them at a point?

So I'm using near-infrared light of the wavelength of order 700-800 nm. I need it focused at one point. I was wondering if using glass lenses would do the job or not?
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1answer
22 views

If final image of object is forming at viewer's eye, where will viewer see that object?

If an object is kept at centre of curvature of convex lens and a viewer is present at centre of curvature of other side then where will he see that object? I think he will see the object at it's ...
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1answer
63 views

Why do parallel light beams converge at the focal point of a curved mirror?

Can someone prove that all parallel lights beams reflect back and meet at point the point $F$? Any help would be appreciated.
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1answer
30 views

Can all aberrations be fully removed by a lens system in theory?

I recently came across an interesting argument (in Mack's "Fundamental Principles of Optical Lithography", beginning of Chapter 3): By adding more and more lenses to an imaging system, more and more ...
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12 views

Why is the reflection of CFL bulb a green spot on my glasses

Why is that if i try to see the reflection of a CFL bulb (the bulb is on) using my glasses i see it as 2 green spots instead of a white light. plus this happens on the outerside of the lenses...not ...
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25 views

Change of a lens' focal point with wavelength. Refractive index wavelength independent

I was using a Comsol example for the focusing lens: https://www.comsol.com/model/focusing-lens-57621 I made no changes to the model. The focal length of the lens is set to be 1000 um. Initially, I ...
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0answers
61 views

Infinity Corrected Microscope vs. $4f$ imaging system

This questions concerns three types of microscope systems and the differences between them. Let me lay out my understanding of these three types of systems. I am imagining imaging with a camera so ...
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0answers
22 views

Designing of a Lens-Optical System

I need the following guidance & help related to designing of a specific type of Optical System Lens Design. Which tool is freely (open source) can be used? is there any possibility of doing a ...
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0answers
28 views

Real image in optics

A real image can be seen on a screen, right. But how we see a real image without a screen, when we have to find out the focal length of convex mirror with the help of a covex lens during class ...
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1answer
27 views

What is the difference between longitudinal chromatic aberration and spherochromatism?

In lens design textbooks, a distinction is often made between longitudinal chromatic aberration and spherochromatism. (See for instance Kingslake's lens design book.) What is simple way to understand ...
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55 views

Gravitational lensing in the form of optical equation $\frac{1}{p} + \frac{1}{q} = \frac{1}{f}$? [duplicate]

Gravitational lensing and light deviation is a well known subject in General Relativity. I'm wondering if the null geodesics equation could be recast into the classical lenses equation: \begin{...
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1answer
21 views

Calculated focus of an asymmetric bi-convex lens

So I've been working on modeling an optical system using ray tracing. I've finally gotten to the point where I am testing things however I've come across something I'm not entirely sure of. I'm ...
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3answers
67 views

Lens with focal length 0

I have been wondering about a limiting case of the focal length. Specifically, a lens with a focal length of $0$. Could that exist in real life, and what would be its meaning? Also, what does it mean ...
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20 views

Gradient Constant of a Gradient Index (GRIN) Lens

I came across this page https://spie.org/publications/tt48_55_gradient_index_lens and was wondering how one would go about calculating the gradient constant, k in this example.
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2answers
25 views

Final Image Position with Multiple Lenses

I am confused on how to calculate the final image position after the two lenses. I understand that the image position of the first lens can be treated as the object position of the second lens, but in ...
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0answers
12 views

Why does the images of slit slip down in bottom as we move the lens?

Why does the images of slit slip down in bottom as we move the convex lens in the experiment of "determination of wavelength of sodium light by fresnel biprism experiment". We made the system coaxial ...
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21 views

Telecentric lens references, working distance formula

I would like to learn about telecentric lenses for use in an experiment. So far, I have found scant resources (mostly optical companies) and I understand the basic principal of a simple telecentric ...
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2answers
92 views

Concave magnifier lens Two questions in one [closed]

Consider a support made from a wide (1m), short (30cm) (approximate sizes just for reference), rigid, empty, open ended cylinder. Cover the ends with a perfectly flexible transparent sheet. Suck the ...
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15 views

Thin lens thickness design

Is there a rule for the thin lens thickness so that it follows the para-axial approximation either with respect to the wavelength or the radius of the lens?
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29 views

How I can add lenses stacked on front of iphone camera to increase magnifying power?

How we can stack different lenses to increase magnifiying power of a smartphone camera? Is there any way to test if stacked lenses will focus light on image sensor of smartphone exactly right before ...
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0answers
14 views

Question regarding demonstration of Poisson's spot [duplicate]

https://youtu.be/y9c8oZ49pFc At around 5 minutes into the video, to show Poisson's spot, the laser beam is made to go through a diverging lens. Is it necessary to use a diverging and why?
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1answer
25 views

Regarding the demonstration of Poisson's Spot

This video is one by Veritasium on Poisson's Spot. https://youtu.be/y9c8oZ49pFc In the later half of the video where he does the experiment by using a laser, why does the laser beam have to pass ...
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24 views

Question about transmission of paraboloidal light waves in bi-convex lens

The question is as follows: Show that a paraboloidal wave centered at $z_1$ is converted by a lens of focal length $f$ into a paraboloidal wave centered about $z_2$, where $\frac1{z1} + \frac1{z2} ...
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1answer
36 views

Is there a way to add lenses together to shorten their focal length?

I need to know if there is a way to put lenses in front of each other to make their focal length shorter. I tried putting them directly in front of on another, but I wasn't sure if there was a better ...
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0answers
10 views

Magnification of a compound micrscope

What is the formula to find the magnification of a compund microscope if the focal lengths of the two lenses and the distance between them are given.
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1answer
86 views

Lens Formula for thick lens

My textbook states that for thin lens formula of lens is i.e $\frac{1}{v}$ - $ \frac{1}{u}$= $ \frac{1}{f}$ and for thick lens $ \frac{1}{v-t}$ $ -\frac{1}{u+t}$ $= \frac{1}{f}$ While the ...
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2answers
45 views

What type of lens is used to collimate light?

I am interested in collimating infrared LEDs, but I don't know what type of lens to use (eg, concave or convex). Can someone tell me what type of lens to use? I am trying to collimate a regular IR LED ...
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0answers
17 views

Polishing Spherical Refracting surface vs Lens

My text book states that When we polish a spherical refracting surface (sphere) it doesn't behave as spherical surface and mirror .It still behaves as spherical surface. The polished side is just ...
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1answer
102 views

(7) Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses? [closed]

Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses?
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1answer
24 views

Image formation and focus

It is known that an image is in focus (and it results sharp and clear) only at the focus, in which all rays intersect themselves. Why do we see sharp images only at the point in which the rays emitted ...
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0answers
9 views

Lens simulator with geometrical optics [duplicate]

I'm looking for a lens simulator to see rays from geometrical optics, possibly easy to use. For now I'm playing with OpticalRayTracer that works perfectly for a preliminary simulation. I would like a ...
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1answer
32 views

Where does energy come from when a laser bean exits lens at c?

Take a laser. Fire it at a lens. Prior to arrival at the lens the lasers pulsed beam’s speed is c. Traversing the lens it’s speed is less than c. Exiting the lens (and back to the vacuum) it’s speed ...
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0answers
24 views

How far will the imaging be? And is it possible to make it farther?

So currently I'm trying to make a smart glasses, where you have a projector that projects an image onto transparent flat glass, and some of the light will reflect into your eyes (something like the ...
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2answers
67 views

Which side is convex in my plano convex lens?

So, I am building an optical system and have got a Thorlabs plano-convex lens (part # LA1172-C) with a 400mm focal length. This makes the convex side of the lens so flat that it is difficult for me to ...
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1answer
46 views

Lens design with few constraints

I'm not an expert in lens design. I need to build a lens having fixed the focal point $f$, the lens diameter $D$, the maximum thickness $d$, the refractive index $n$ and the half-angle $\theta$ ...
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0answers
44 views

Raytracing on convex spherical surface, where n1>n2

I'm reading my textbook and I'm trying to figure the ray tracing of a single point of this one case that the book doesn't cover. My question is, what does the ray tracing look like when we have a ...
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2answers
53 views

How do lens capture reflections clearly?

In an optical system which uses lenses (cameras, our eye) multiple rays from the same point are conveyed in a single point on the retina / image sensor. This is typically shown as in the image below. ...
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1answer
57 views

Focal Length, Wavelength Relationship

I have a cylindrical lens with a design wavelength of 587.6nm. The radius (S2) of the lens is 2mm, and the radius of the opposite face (S1), i assume is 0mm. The focal length is given as 3.91mm and ...
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1answer
34 views

Telecentric lens system with gaussian optics

I often use bi-telecentric lenses at work, which means both object-side and image-side chief rays are parallel. However, as I don't really have an optics background, I'm a bit baffled at how this ...
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2answers
137 views

How to find the radius of curvature of plano convex lens? [closed]

The information available about the lens are Refractive index n Aperture diameter d Maximum thickness of the lens t Is it possible to calculate the radius of curvature of the lens using the above ...
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0answers
19 views

How can I determine the optics needed for a desk microscope?

As an noob to microscopy, photography, and optics in general, I'm trying to figure out if I can use the KPPACE KP-2100 camera as a desk electronics microscope. I want something I can mount to the ...