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Questions tagged [lenses]

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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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22 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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Question regarding demonstration of Poisson's spot

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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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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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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Focus Beam Angle of LED Light with Relective Surface [closed]

Will the majority of the light from the LED source be focused using the following angled polycarbonate surface? The LED beam angle is 130. I'm trying to reduce to 30 degrees. If this would work, any ...
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1answer
35 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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8 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
36 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
30 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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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
69 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 ...
2
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1answer
30 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
48 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
45 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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31 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
48 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
21 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
25 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
45 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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16 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 ...
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1answer
127 views

Determining the focal length of a convex lens (no-parallax method)

This is about the experiment where we determine the focal length of a convex lens using the graphical method,(the no parallax method). In the situation where the image moves opposite to the direction ...
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3answers
71 views

How do lenses magnify images?

Using the ray model of light helps us to model what happens when a ray of light enters in to the lens. right? but doesn't tell us how? As you can see in this image the rays of light are converging ...
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1answer
50 views

Can an object at the focal length of the eye be seen?

It is known an object put at the focal length of a convex lens isn't visible since there aren't any light rays that intercept either real or extended. And it is known the eye is a convex lens. So what ...
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0answers
38 views

Do virtual images exist in the real world? [duplicate]

I have been reading an article here in physics stack exchange that talks about if it is possible to see virtual images, and i read an answer saying it is actually your brain that understands the ...
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0answers
16 views

How to choose plano convex cylindrical lens to correct astigmatism

I need to correct horizontal astigmatism using plano convex cylindrical lens. Correction is needed because rays goes through pair of prisms. So I dont know how to compute radius of curvature of lens. ...
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3answers
82 views

When does the retina fail to recognize images of two closely separated points as distinct?

Our eye is a lens and lenses have a resolving power. The resolving power of a lens, physically speaking, is related to how good two closely separated points A and B can be distinguished as separate. ...
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0answers
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How can I focus a laser in the gap between two slits?

I’m trying to focus a green laser in between two slits. The slit width is 0.2mm and gap between the slits is also 0.2mm. I measured the laser’s minimum spot size. It’s elliptical with major and minor ...
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1answer
38 views

Parabola black body heating

I'm having trouble figuring out why this following example of shenanigans wouldn't work. If you take a parabolic mirror (say from polished aluminium) with a magnification of M and construct it such ...
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2answers
56 views

Does phase change occurs on refraction at a lens?

There is no phase change between refracted (transmitted) rays and incident rays, according to boundary conditions of electric field and magnetic field, in accordance with the Maxwell's equations and ...
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1answer
54 views

What is a 3rd-order Fresnel lens?

The NPR News article and podcast Job Opening: Seeking Historian With Tolerance For Harsh Weather, The Occasional Bear talks about the Split Rock Lighthouse. That Wikipedia article links to the image ...
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1answer
23 views

Virtual and Real Images

I am well thorough with the concept of virtual and real images for a single lens/mirror. However I don’t understand how it exactly works for complex system of lens .eg-two or three lens with a ...
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1answer
22 views

Determining lens and sensor distance for narrow focus

I have the following items: a round target object, approx. 6mm in diameter a lens, focal length 20mm, F/2.8 a camera sensor, optical size 1/4" (note: I know this camera has a fixed-at-infinity lens, ...
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1answer
32 views

Holographic “lens” - controlling light diffraction angles with silver halide film

I'm trying to develop a way to control the "exit angle" (diffraction angle) of a monochromatic light source. For example: taking a laser; spreading the beam; and directing the light at a piece of ...
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1answer
56 views

Focal length for thick lens [closed]

How can I find the focal length of a thick lens by the method of ray tracing ? I know the ray matrix method but by ray tracing I don't get to an answer.
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2answers
61 views

Why do we see things upside-down when we’re upside-down but not a camera?

If I do a handstand, everything looks upside down (which is originally what we see if we’re upright but the brain switches this). I assume this is because the change in how light rays enter our eye. ...
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0answers
26 views

Hard Lens Question

In the explanation to this question, it states "the 140cm focal point is where the image needs to be located". Can someone explains what this means? A certain farsighted person cannot focus on ...
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27 views

Interference using composite lens

I encountered a question while attempting an exam. I cannot really understand how to go about it. It is clear that the concave part forms the image at a distance $3 \lambda /2$ behind the lens, and ...
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2answers
41 views

Polarised glasses for high astigmatism and myopia [closed]

So I have -4 for both of them, which results in -8 in total (same for left and right eye). At my optician, I have to choose the best package they have to make sure my sunglasses can be as light as ...
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1answer
13 views

Does the order of analysis matter when considering multiple lenses and mirrors?

Say we have an object $O$ that is to the left of two lenses. Let's say that the first lens $L_1$ is to the left of $L_2$, the second lens. Assuming we know the type of each lens (concave or convex), ...
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0answers
31 views

Optics that translates object to image by a constant amount

For some application I was interested in an optics s.t. for any incoming ray the outcoming ray is parallel to the incoming ray and shifted by a distance $d$ (independent of the incoming ray) along the ...
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1answer
43 views

How to know if a thick lense system is divergent or convergent

I know that the sign of the effective focal lenght (f) of a lense will determine if a that lense is divergent(f<0) or convergent(f>0), but with a system made of a combination of thick lenses and ...
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0answers
28 views

The ideal shape of a plano-convex lens

What's the type of the ideal shape of a surface of a plano-convex lens to focus a parallel beam at the point? Considering the lens turned its flat side to a beam. Surely it must be aspheric: ...
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2answers
92 views

Prove that a converging lens has 2 object distances for which there exists an image

I've been struggling with this for a while now. I feel that proving this is actually way easier than what I think it is. I'm just going to copy paste the question here: A light bulb (the object) is ...
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1answer
215 views

Seeing virtual image in convex lens of object kept beyond focal point

Beyond the focal point, $f$, a convex lens only forms real image. However, I see an inverted virtual image of a distant object when looking at the lens from a distance. If the image of the distant ...
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3answers
55 views

Why do we see an object with more clarity if more light rays from it enter our eye?

When I ask people what is the difference between more light rays diverging from a point and entering our eye and less rays diverging from a point and entering our eye.They say that more the light rays,...
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3answers
68 views

Virtual images - Work of a brain or work of a lens?

I am just a high school student trying to self study, so please excuse me if this question sounds silly to you. Many people tell me that virtual images are formed when two rays that are diverging ...