The lenses tag has no wiki summary.
0
votes
1answer
25 views
Effect of slits and a lens
We have a screen with two slits (Young style) separated by a distance $d$, one of them receives a planar wave of $600nm$, the other receives a planar wave of $400nm$. Behind the slits there's a screen ...
1
vote
0answers
46 views
Hows lensmaker formula works? if Radius is zero?
I am doing my revision and there's such a question. However, when I tried to plug the values into the lensmaker formula, I find that one of the R is equal to zero, as it is not curved.
$(n_2 ...
0
votes
0answers
23 views
How can I get the focal length from the given information? [closed]
A man looks at a tree of height 20m a distance of 300m away. The reduced model of the eyes assumes that the cornea has a radius of curvature of 7.7mm, the eye is composed of the material with a ...
1
vote
1answer
29 views
What is “field size” when referring to perspective?
I'm trying to get my head around perspective.
If you look at the animation in Wikipedia :
You can see that the cube looks very distorted, then the edges go more parallel.
From my understanding, ...
2
votes
2answers
80 views
Proof that a spherical lens is stigmatic
In geometric optics, we generally allow that, for example in the case of a convex lens, rays coming from a particular point get refracted towards another particular point on the opposite side of the ...
0
votes
2answers
39 views
Paraxial rays and marginal rays question
Paraxial rays are found to focus far away the lens whereas marginal rays focus near to the lens, why? I didn't find satisfactory answer in my academic book..
3
votes
2answers
58 views
How to draw a ray diagram from focal length, object and image heights?
Q. An object of height 8 cm is placed in front of a lens. It's inverted image of height 4.8 cm is formed on the screen. If the focal length of the lens is 12 cm then by drawing at scale calculate the ...
1
vote
1answer
134 views
Calculate the distance between two points from iPhone Camera
I want to calculate the distance between two objects using an iPhone camera.
Suppose I'm standing with my iPhone 10 feet away from the objects. Now, I want to calculate the distance between those ...
0
votes
1answer
16 views
Convergence of Light on the Retina
So, I've learned about lens ray diagrams-but the problem I'm having is that when ray diagrams are drawn for a point of an image, they converge to another point, but there are two problems that I see ...
0
votes
1answer
66 views
How to calculate beam spread of a non-point light source via an aspheric lens
I need to determine the angle, or rate of divergence of light from a single aspheric lens when I place a non-point light source (e.g. LED array) at a given distance from the lens which is less than ...
3
votes
1answer
48 views
Optics, lenses and our eyes
When we view an image, is the focal point of our eye on our retina? Shouldn't that hurt?
Also, if that is how our eye works, then why don't lenses put the focal point their equivalent retina? I was ...
2
votes
1answer
94 views
Why do focal lengths affect magnification?
For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens.
In telescopes, the objective lens projects an image on its focal point which works as the object ...
1
vote
2answers
102 views
How does the eye perceive a real image?
Okay, so I'm trying to grasp how the human eye will perceive the real image created for example by a convex lens. Take the upper image in this picture for example.
If you were to place a screen at ...
14
votes
1answer
2k views
Why can you see virtual images?
In optics it is widely mentioned real images are projectable onto screens whereas virtual ones can only be seen by a person. Isn't that contradictory? I mean in order to see the virtual image it has ...
0
votes
2answers
312 views
Magnifying Glass-How does it work? [duplicate]
How does a magnifying glass work? I know it creates a virtual image of the observed object but how is it possible that humans can see the virtual image?
0
votes
0answers
259 views
Why a person with a further near point experience a larger magnification with a magnifier
Two people, Micah and Lyra, with different near points are equally
close to an object. Both inspect the object through the same magnifier
by holding the lens close to the eye. Micah's near ...
1
vote
1answer
77 views
What determines the sign of an image distance?
A lens placed at the origin with its axis pointing along the x axis
produces a real inverted image at $x = - 24 cm$ that is twice as tall as the
object.
What is the image distance?
Why ...
2
votes
0answers
39 views
Smaller Airy disk with another lens?
Is it possible to reduce the airy disk size produced by one lens with another lens placed after the previous one? For example, parallel ray incident on first lens L1 (without aberration), then there ...
0
votes
0answers
42 views
EigenMode expansion for beam propagation
I want to understand how to apply EigenMode expansion method (http://www.photond.com/files/docs/PW03_eme_paper.pdf) for beam propagation on a system of lenses.
The interface between two mediums of ...
0
votes
1answer
168 views
calculating focal length of meniscus lens
As I read about telescope, distance between objective lens and eyepiece must be equal to addition of their focal lengths.
D = F1 + F2
I used one of the eyepiece ...
3
votes
2answers
335 views
How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?
I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm.
I ...
4
votes
1answer
130 views
On the optics of high-resolution surveillance drones
In this youtube video (which is an except from a documentation I believe) a DARPA development for a high-resolution surveillance camera is presented. This question is regarding the optics that are ...
7
votes
3answers
130 views
Put a sensor at the focal length, behind, or in front?
My intuition tell me that at the focal length a convex lens all the light converges to a point. Following that logic, it would make sense to me that a camera chip would either need to go slightly in ...
0
votes
2answers
108 views
Ideal distance of eye from a lens
I observed that when I keep constant distance between object and lens but I move my eye, I get different magnification. When I am closer to lens I can see large image of the object. But if I go away ...
3
votes
2answers
151 views
Effect of gas or liquid within a compound lens system
Hi my question is if a compound lens system if filled with gas or a liquid how does it affect the system when compared to the lens system being separated by air alone. Does this affect the focal power ...
1
vote
2answers
90 views
Is it possible to enlarge the output angle of a projector with outside lens?
I have a very small projector, with a small output angle (30 degree). In my current demand I want a bigger output angle(90 degree), so that I can get a bigger image within a given distance. Is it ...
0
votes
0answers
41 views
How does a lens affect the field of view in a mirror?
If one looks into a mirror, he can see a certain field of view.
If he places a convex lens that magnifies (or a concave lens that does the opposite) in front of the mirror, but so that he can still ...
1
vote
1answer
129 views
Optics Paradox?
Imagine we have two lens, one convex and one concave, spaced in such a way that the convex lens is before the concave lens. Now each lens has its own focus length and both are spaced such that the ...
1
vote
3answers
535 views
What does the optical zoom in telescopes do?
How does the optical zoom works..
Does it brings the light closer to the object... Or
Does it just enlarges the picture of the object.
In other words... Suppose I have telescope with 1 light-year ...
-4
votes
1answer
70 views
Photonics: Slab As a Lens [closed]
The question can be found here: http://gyazo.com/fc4d26cd35e6ce368ad2a8ed504f1dcc
The refractive index it references can be found here: http://gyazo.com/94fd2f3b5ea7da9226c3acd56b0024c1
I'm not ...
2
votes
1answer
1k views
How to find focal length of a single convex lens?
I need help finding the focal length of a single convex lens. The radius of curvature is 200mm. left side is air and the glass has a index of 1.5. I search on google but there was only formulas for ...
14
votes
3answers
387 views
What are these rays that appear in photograph of sun?
In many images of light emitting objects we see such rays. Why do they appear ?
What is the math behind their number and direction?
-3
votes
1answer
85 views
can someone describe the image which will be formed on the retina of the human who sees this image [closed]
I was trying to analyse the image which i have put here.
can someone describe the image which will be formed on the retina of the human who sees this image.
2
votes
1answer
204 views
How does a flat wedge lens work?
I've been seeing this lens in a lot of places especially microsoft:
http://www.youtube.com/watch?feature=player_detailpage&v=rJ1p5SD3sOM#t=45s
...
0
votes
1answer
122 views
How to define the required aspherical coefficients for a lens?
I would like to purchase my own aspherical lens for testing purpose. Then I need to define the required coefficients. But how?
My known requirements are f=25mm F/# 2.0 and MTF 0.5 @ 120lp/mm with a wl ...
2
votes
1answer
151 views
Curved lines in a picture (Photography)
My problem is when I take a picture (a close one) the straight edge looks a little curved. In a standard camera, like a CyberShot.
I would like to know if there is some relationship between the ...
3
votes
1answer
313 views
Compound lenses and virtual images
Ok so I have this problem where I have a system of two lenses. All I know is that the distance between the object and the first lens is 30cm, the distance between the object and the final image is ...
1
vote
1answer
104 views
Do eye-glasses decrease the Depth of focus?
I was reading up about Depth of Focus and wondered if glasses affect depth of focus. If yes, is it noticeable to the user?
