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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1answer
389 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?
5
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2answers
77 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 ...
5
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2answers
8k 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
39 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 ...
0
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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 ...
0
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1answer
48 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 ...
1
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1answer
25 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 ...
1
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1answer
42 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 ...
0
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1answer
23 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 ...
3
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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 ...
40
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5answers
5k views

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
45 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.
2
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1answer
52 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 ...
1
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2answers
81 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 ...
1
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0answers
25 views

Analytical calculation for focus deviation [closed]

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. ...
4
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2answers
508 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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0answers
56 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 ...
2
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3answers
65 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 ...
4
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2answers
115 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 ...
13
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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 ...
26
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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 ...
2
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1answer
45 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 ...
0
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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 ...
2
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1answer
36 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 ...
0
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1answer
18 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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3answers
107 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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0answers
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 ...
0
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1answer
28 views
3
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1answer
45 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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0answers
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
23 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
138 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 ...
3
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2answers
4k views

Radius of curvature and focal length

Is the radius of curvature of a convex or concave lens longer than the focal length of the lens? Does the center or curvature affect the focal point in a lens?
7
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2answers
200 views

what happens inside linear polarizer sheet (at microscopic level) when unpolarized light falls on it?

(1) What happens at microscopic level when unpolarized light falls on a linear polarizer sheet ? i.e. Due to what thing inside polarizer sheet, only those EM waves are passed whose plane of vibration ...
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0answers
36 views

optical properties of metal-dielectric-metal microcavities

I would like to figure out the optical properties of metal-dielectric-metal microcavities, used in the fabrication of micro patch antenna. The paper that I'm reading is this one. Now the specific ...
1
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0answers
33 views

Cheap DIY Zernike-Phasecontrast: Optical Thickness of a inkjet/laser printed contour for phasering? [closed]

Rough guess: Optical Thickness of a inkjet/laser printed contour? Edit I was wondering if there is any research regarding the refractive index and the height of an inkjet or laser printed contour?  ...
7
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3answers
12k views

How does the grid on the microwave oven window prevent microwave radiation from coming out?

If I look through the microwave window I can see through, which means visible radiation can get out. We know also that there is a mesh on the microwave window which prevents microwave from coming out. ...
2
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1answer
45 views

How come we can get mirror-like effects from dark surfaces?

Question: If I understand correctly, an object's color is determined by the optical frequency which it does not absorb. So an apple appears red because it only reflects red. My question is, if this is ...
0
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1answer
22 views

Reason for absorbance

First quoting the example which raised my curiosity"when light passes through polaroid it absorbs certain direction light rays" My question is how this phenomenon of absorbance occurs is this some ...
48
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7answers
24k views

Why glass is transparent?

Once I asked this question from my teacher and he replied "because it passes light", "and why it passes light" I asked and he said "because it is transparent". Same question again, Why glass is ...
5
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0answers
37 views

Does the curvature of the IMAX screen improve the view of 3D video projections in any way for viewers not sitting in the “sweet spot”?

When I think about a simple 2D projection on a screen with vertical-cylinder curvature and of viewing positions away from the "sweet spot" it seems to me pretty obvious that there would be geometrical ...
5
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3answers
1k views

Could the sky on a planet theoretically be any color?

The sky on the Earth is blue. Could the color of the sky on a planet with an atmosphere be of any color theoretically? Which colors are the most likely? I think it would be really awesome to have ...
0
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1answer
30 views

Does crossing your eyes to see stereoscopic images provide the same effect as unfocusing your eyes (looking into the distance)?

Not sure if this is the best place to post this. Please correct any formatting/grammatical errors I've made!
2
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0answers
35 views

How small can a spherical clear glass bead be before it loses it's transparency?

I don't know if it'll help but I'm trying to use these as tracker particles in water. Edit: I mean it'll start scattering light. I know glass beads of size about 30 micron and less appear white under ...
-3
votes
1answer
136 views

Quarter-wave stacks and rejection filters to protect flight crews' vision from visible laser pointers [closed]

I would like to know how the physics(and possibly mathematics) for how quarter-wave stacks could be utilized to make an ideal rejection filter that rejects all visible coherent green or blue or red ...
0
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2answers
88 views

Does every past state of the Earth currently “travel” through the universe?

So I just read this question. The 27 year old user asks if it would be possible to see his own birth if he would be 27 lightyears away from the earth and the answer states ...
9
votes
4answers
4k views

Three polarizers, 45° apart

If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
3
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1answer
56 views

What are these microscope circles?

This is a photo I have taken with a microscope (100x objective). What are these circles? When I rotate the eyepiece or the objective they stay still. Are they particles on the mirror? In this case ...
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0answers
27 views

Double Fraunhofer , Fourier transform to the image plane?

Consider the diagram below: I know that from Franhofer diffraction we have: $$u_f(x_f)\propto \int u_o(x_o) e^{-k\frac{x_f}{f}x_o} dx_o$$ Assuming small angles. I also know that $u_i(x_i)$ is ...