Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.

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Why do we have perspective in space? [on hold]

In the Euclidean space there is nothing like perspective but in vision there is something like perspective. How does our sight give rise to perspective? Is it a physical (as opposed to psychological)...
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20 views

Minimal size of an optical lens

Is the minimal size of an optical lens (diameter, width and curvature) limited by the wavelength of the incident light?
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12 views

Question about experimental achievement in Optical phase conjugation

As I read here https://en.wikipedia.org/wiki/Nonlinear_optics#Optical_phase_conjugation it is very interesting thing. What is real experimental achievements in this area or everything works only in ...
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1answer
39 views

What is the angular divergence of sun-rays?

I just want to find a number and I could not. Does anyone has it or can calculate it easily? Just in geometric optics, without diffraction, atmospheric effects and etc. Update: I think for me will be ...
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1answer
769 views

Definition of pole of a spherical mirror

what can be a suitable definition to a pole of the spherical mirror. It cant be the geometrical center of a spherical mirror as if a mirror is cut then its pole does not change. moreover if a ...
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3answers
213 views

Optical path difference

I have question about calculating optical path difference. $$\Delta L = \mathrm{(BC+CD)}\cdot n_2 - \textrm{BF}\cdot n_1$$ - why calculating path difference here we are subtracting $\mathrm{BF}$ ...
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7 views

What is the ray diagram for Schuster's focussing?

I haven't been able to find it online. Our course book also doesn't provide a ray diagram for this particular phenomenon. I feel like it's difficult to understand the process without the ray diagram.
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1answer
366 views

What's the size of the smallest possible CCD/CMOS pixel size?

For a given wavelength $\lambda$, is there a limit on the size of the sensor pixel, regardless of the optical equipment attached to the sensor?
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2answers
66 views

Can we see/detect things which don't have electrons

Whenever we sees a thing the process happening at atomic level is the electrons of that stuff absorbs the energy from packets and goes to higher state and then comes to ground state and emits ...
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0answers
18 views

What do we mean by angle of incident equals angle of reflection? [duplicate]

When we incident light on something the electrons of that stuff absorbs the energy goes to higher state and then come back to ground state and emits radiation so my question is what is happening at ...
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2answers
7k views

Relation between Radiance and Irradiance

I know the radiance is expressed as $$\text{[Radiance]} = \frac{W \cdot m^2}{\text{sterad}}$$ and $$\text{[Irradiance]} = W \cdot m^2$$ But what's the relation between theese two quantities? Is the ...
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0answers
29 views

Simulating a noisy image: Poisson Noise Clarification

I'm currently working to simulate an image that mirrors the output of a CMOS camera we have in the lab. My images include Poisson (photon) noise as well as a gaussian (readout) noise. My issue is ...
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45 views

How are coherent astronomical objects imaged?

I am studying astronomical imaging, and am curious about how to image astronomical objects which are coherent. Stellar interferometry measures the mutual coherence function of a star, and then uses ...
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0answers
9 views

How do optical anti-aliasing filters work from a frequency domain perspective [migrated]

To prevent aliasing, caused by the finite number of pixels on a sensor, a blurring filter is commonly used. How does that work from a frequency domain perspective? What is the transfer function of ...
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1answer
42 views

Uncertainty and Classical waves

My professor, introducing Heisenberg uncertainty principle, started from the Fourier transform and the classical uncertainty for waves. He told about the localized impulsive wave $\delta(x)$ which ...
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1answer
22 views

Reflectivity of Metallic surfaces

Can someone please point me to an academically verified web resource/page that tabulates the Reflectivity of various metallic surfaces like gold, silver , aluminium etc? I have found a list on ...
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2answers
74 views

What is the optimal distance to sit from a TV? [on hold]

I was wondering how to calculate the optimal distance to sit away from a TV. I don't quite know the full set of parameters it will depend on, I would suspect it to include the following: Size of the ...
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1answer
33 views

Why does length of objects seem different in different configurations of object and observer?

Today, I had gone to my friend’s garden. There was a dried water well in his garden. We got curious that know how much its depth is. First, we stood on top of the well and estimated its depth. We ...
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1answer
20 views

Are there interference effects for light that is reflected at an angle?

I am imagining a glass substrate with a thin coating that has a 1/4th wave optical thickness. I understand how this acts as a basic anti-reflective coating for the one wavelength for which it acts as ...
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0answers
88 views

Optics: finding total power of a system, including wavelength

Specifically I need to create an ABCD matrix given 2 radii of curvatures, the thickness of the lens, type of glass (BK7) and a given wavelength. I will have to figure this out eventually, so help ...
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5answers
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If a lens focuses all incoming light to a point, how do we get 2D images?

How do lenses produce 2-dimensional images, if a lens bends all incoming rays of light to intersect at the focal point? Shouldn't this produce a single dot of light on a screen placed at the focal ...
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1answer
29 views

Why does a blue book appear black in red monochromatic light?

Why does a blue book appear black in red monochromatic light? I found the question on this website but it doesn't provide an explanation.
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41 views

Large angle of incidence equation for the Fabry Perot interferometer

What is the large angle of incidence equation for the Fabry Perot interferometer operating in the visible light spectrum? Most optics textbooks only derive the small angle of incidence equation for ...
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1answer
146 views

Physics of detection of coherent light in an incoherent background using the more compact Fabry Perot interfeometer?

I read University Of California Berkeley Professor J. Bokor's Chapter 7 course notes , shown below as an imgur image , on Temporal Coherence tonight. I am sending an email to Professor J. Bokor ...
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1answer
48 views

Why don't windows and mirrors cancel light? [closed]

So I understand that when light goes from a material of low index to a material of higher index it picks up a phase change of 180. Most glass has an index of around 1.5. I know that when light goes ...
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2answers
80 views

Why do we restrict to electric field when describing light?

Why do we restrict only to electric field when describing light as electromagnetic wave? I mean from Maxwell equations we can derive wave equation for electric field and also for magnetic field but ...
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0answers
25 views

Analytical calculation for focus deviation [on hold]

How can I analytically calculate the deviation in focus or focal length variation in a situation as shown in figure. When the Sensor is parallel to the face of the lens/ light; its easy to calculate. ...
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2answers
495 views

double slit experiment with two opposite quarter waveplates

Consider the usual double slit experiment involving laser and a double slit and a screen. Now place in front of the left slit a quarter waveplate (let's call it QWP1) that changes a certain linear ...
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51 views

How was microscope-level zoom created by a lens and a water droplet?

It was a rainy night. My glasses were speckled with fresh water droplets. I looked at a distant street light and I was surprised to see cells - a single cell was zoomed in to the level where I could ...
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1answer
108 views

Fraunhofer Diffraction and Lenses

Suppose we have the diffraction pattern for a single slit in the Fraunhofer approximation. In order to see this diffraction patter at finite distance we locate a converging lens. Is the diffraction ...
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14 views

Geometrical Optics- spherical surface [closed]

A spherical surface of roc 10 cm separates 2 media x and y of refractive indices 3/2 and 4/3 respectively. Centre of the spherical surface lies in the denser medium. An object is placed i x medium. ...
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3answers
64 views

How to distinguish light rays coming from objects of different material

Motivation: My major focus is on Digital Image Processing (specifically segmentation). Due to external noise, the different parts of an image are not fully quantized. Therefore, various segmentation ...
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2answers
90 views

Why is it easier to get sunburnt in the water? [duplicate]

I went today to the swimming pool and I remembered that when I was younger my mom used to tell me to be careful because you get sunburnt much more easily in the water than in the ground. I never gave ...
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2answers
2k views

Why do thin films need to be thin?

No matter what thickness a piece of glass is wouldn't its optical thickness be close to an integer multiple of a wavelength such that it could create interference effects? I feel like I am missing ...
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22 views

Difference between linear magnification, axial magnification and aerial magnification (w.r.t. mirrors)? [closed]

Please explain how the three types are different from each other using pictures (preferably) or diagrams. And if possible, an explanation regarding how each would be different for mirrors and lenses ...
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18 views

How to calculate the reflected light at normal incidence for a piece of glass?

So I am imagining a piece of glass with an index of $n = 1.5$ Lets say that a beam of light is coming in from air $n=1$ at normal incidence. I was using the equation for the reflection coefficient: $...
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5answers
4k views

How do those T-shirts that change color in the sun work?

When I was a kid, I asked my dad about them and he said (not in so many words) that it was because sunlight and artificial light have different spectrums and they picked colors that reflect only the ...
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1answer
38 views

How are iris diaphragms used in laser alignment?

I've read in many places that one of the canonical uses of iris diaphragms is to align a laser beam, but I'm having trouble understanding how this works, since I can always setup a set of arbitrarily ...
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3answers
56 views

Is the light emitted by a laser a 'beam' or a 'ray'? [closed]

In English, the light generated by a laser is almost always referred to in technical texts as a 'laser beam'. However, in French, Spanish, Portuguese and Italian, forms that correspond to laser beam ...
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1answer
33 views

Center of gravity of the photon beam

I have a conceptual question: In singular optics the orbital angular momentum (OAM) is represented by two components: intrinsic (no relation to spin!) and extrinsic. The first one is associated to ...
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1answer
17 views

fiber optic face plate physics-opaque to transparent behavior based on distance of object?

Please look at this video below. its of fiber optic plate or compressed fiber lens Here it seems that the object- which is the book or letters here, is visible only when the plate is touching the ...
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1answer
223 views

How would we see the earth if refraction of light was significantly stronger?

On worldbuilding.SE there is a question about the cosmological consequences of a world with super-high refraction and atmosphere opaqueness. I'm assuming the easiest way to minimally change the laws ...
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3answers
71 views

what is the purpose of condenser lens in a slide projector?

What if we don't use any condenser lens? can't we use a single convex lens as a condenser? what difference will it make? kindly explain it in detail.
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23 views

What is the purpose of condenser lenses in the slide projector shown below? [duplicate]

I searched a lot on internet about this.I could not find the working of these condenser lenses in detail. Some websites say that condenser lenses make the light rays parallel and to pass through ...
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1answer
28 views
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37 views

Reflection and refraction of single photon incident on a glass slab

If a single photon strikes a glass slab of certain thickness, can we make prediction whether it would reflect or refract? On which factor the reflection or refraction of single photon through such a ...
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15 views

opaque to transparent based on distance of object?

If we look through a transparent glass window of an apartment, from a distance in day light, we can’t see what or who is inside. All the light is reflected off the surface of the transparent glass ...
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1answer
22 views

What makes an object reflect the colour that we see?

If a rubber ball is red, I know that it is absorbing all colours except for red, which it is reflecting. So there is not actually a part of the object that contains any red. But what tells an object ...
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2answers
133 views

Single Slit Diffraction

I am trying to derive the intensity variation function for a single slit diffraction. Sorry for the poor diagram... So I decided to take the amplitudes of the waves originating from the slit on the ...
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2answers
124 views

What's the meaning of partial derivative for radiance?

The definition of radiance is: $$L\equiv\frac {\partial^2 \Phi}{\partial A\,\partial\omega\,\cos\theta}$$ where: $\Phi$ is the radiant flux $\omega$ is the solid angle $A\cos\theta$ is the ...