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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Is the glass made up of holes that let the light to go through it?

The following passage has been extracted from the book "The Magic of Science-A.Frederick Collins" (1917): Substances of all kinds have pores or holes in them. A sponge has pores that can be ...
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71 views

What will happen if two photons collide perpendicularly? [closed]

Suppose there is an object placed at (-1,0) on x-axis. A light ray coming from it is observed by an observer somewhere on positive x-axis. In addition, a second object is placed somewhere on y-axis. ...
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182 views

Can there be a string so thin as to be invisible, but that can still support a visible weight?

A spider web thread is very thin, yet it can support a spider. Given that the human eye visual acuity is finite, are there materials, natural or man-made, sufficiently thin that a string made from ...
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2k views

Why is the focal length of a convex mirror negative?

According to the Cartesian sign convention, the focal length should be positive since the convex mirror forms a virtual image to the right of mirror (positive direction) when light comes from left. ...
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What are the factors affecting transparency and color of a substance [duplicate]

What is the reason behind visual properties like color and transparency of different substances? I have always heard that the structure of the substance is responsible for these properties. I always ...
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775 views

Can this simple spectrometer be precise without collimation?

Consider the following spectrometer structure: Here the slit can be changed in size, and the lens and detector can be moved closer to or farther from the diffraction grating. I was trying to get ...
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30 views

Absorbative polarisers

Absorbative polarisers are one way of getting linearly polarised light from an unpolarised beam. The key idea is that these materials are manufactured such that light can be absorbed in all ...
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Ellipsometry measurments

Why it is good to measure on a wavelength range in ellipsometry instead of using a single wavelength. I understand this that the measured data (ψ and ∆ ) plotted against wavelength and if we have ...
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5answers
391 views

Is there a limit to the frame rate achievable with a high-speed camera?

A high-speed camera is a device used for recording fast- moving objects as a photographic image(s) onto a storage medium. A normal motion picture is filmed and played back at 24 frames per second, ...
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391 views

Laser beam divergence

How can I calculate the divergence of a laser beam by diffraction? I want to find the following relation, $$ \Delta\Omega = \frac{\lambda^2}{A}, $$ where $\lambda$ is the wavelength and $A$ is the ...
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190 views

What is the ratio power in core/ total power in an optical fiber?

I need to plot a graph of power_core/total power in optical fiber with respect to $V$ Number: searching on the internet I got this formula: ...
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397 views

Problem in ray diagrams in convex mirrors

I just found out about the Desmos online graphing calculator, and it is really a very nice tool. Just while playing with it, I had the idea of creating simulations. I decided to make a simulation of ...
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120 views

Broken Thin Lens Algorithm [closed]

We all know the thin lens equation. For $o$ being a horizontal object distance and $f$ being the focal length, the horizontal image distance $i$ is described by: $$\frac{1}{f} = \frac{1}{o} + ...
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95 views

Why do roads appear wet on hot days? I do not understand [duplicate]

Why do roads appear wet on hot days? I don't understand the bending of light rays in relation to the density fluctuations. How are they related? Why do we see mirror images of cars on road in hot ...
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58 views

Entanglement g-2-experiment - Which components do I need?

I would like to measure whether my source emits entangled photon pairs. To that order I want to build a g-2-experiment, which measures photon coincidence counts as a function of time delay between ...
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3answers
101 views

What defines camera's size?

Smartphone camera is small while others are big. I know some functions like zoom can change physical size and multi lens,.. etc So, assume that a without zoom, what define camera lens? I want to get ...
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2k views

Effective refractive index calculation of fiber core

Can someone pls explain what is effective refractive index of fiber core and how to calculate it theoretically? Suppose the fiber core refractive index=1.4446 and cladding refractive index is= ...
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2answers
349 views

Is there a mathematical equivalence between gravitational optics and quantum optics or are they mathematically incompatible theories?

I know that massive gravitational bodies will curve the path that light travels. I think that quantum optical mediums also bend light. I am still confused of whether quantum optical mediums actually ...
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152 views

Phase shift in back-reflection generated at the mating point of two fibers

If you have light traveling from glass to air at normal incidence, e.g., in an optical fiber with the endface open, the Fresnel reflection coefficient would roughly be $R = |(1.5-1)/(1.5+1)|^2 = 0.04$ ...
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100 views

Transfer matrices - drift distances

I have a question regarding transfer matrices in optics. For thin lenses, the thickness of the lense is not taken into the calculation because it is very small compared to the dimensions of the rest ...
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44 views

Mie theory “upper limit”?

I have read most often that objects experimented with in Mie theory are on a scale not much larger than the incident wavelength (usually a fiber of diameter $5$ microns with an incident wavelength of ...
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51 views

Silicon/silicon dioxide interface

Suppose we have an interface of silicon/silicondioxide. If we shine light on the top surface electron-hole pairs are generated in silicon. since there is always a field directing from surface to bulk ...
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2answers
135 views

How to define a convex surface in case of refraction?

In an exam at high school level, it was said, "ray goes from optically denser to rarer medium through a convex surface. It forms a real image...." this was a part of the question. Now I thought that ...
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378 views

Light-matter interaction and an object's appearance

I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories: mirror like glossy or specular diffuse He suggested that the law of reflection is ...
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570 views

How to calculate the refracted light path when refraction index continuously increasing?

Suppose an incident light from vacuum ($n_1=1.0$) into some media ($n_2=n_1+\mu\; x^2$) as in the figure below. How to calculate the refracted light path curve in closed form? Update: Try to set ...
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114 views

Is the image formed at the retina messy?

The following passage has been extracted from Newton's book Opticks: ...So if PR [in Fig.at the top] represent any Object without Doors, and AB be a Lens placed at a hole in the Window-shut ...
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264 views

A mirror in the sky to look at past Earth

Earth reflects light from Sun into Space; are there any "mirror like" objects which reflect back to Earth this light? Has anyone been able to use this method to recover some information on how was the ...
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91 views

Can we multiply an electromagnetic field?

can we multiply light by a sequence of reflections in a closed vessel? also, is light a part of EM wave? can we multiply the radio wave or EM wave from a transformer?
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140 views

The lineshape of a 2D photonic crystal dispersion diagram

Using simulation software (CST Studio), I calculated the dispersion of the eigenmodes of a photonic crystal, that is frequency vs wavenumber for the desired propagation direction. I wonder what kind ...
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2answers
524 views

Refractive index of dielectric in different frames of reference

The setup A transparent isotropic dielectric medium moving in the negative $x'$ direction at speed $v$ in frame $S'$ is stationary in frame $S$, where it has refractive index $n$. In other words, ...
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174 views

Sum of 2 Light sources

When we have 2 sinusoidal waves with slightly different wavelengths and the same amplitude, the resulting wave has a changing amplitude (amplitude = intensity) which varies from 2*Amplitude to 0 ...
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3answers
573 views

Microscope Objective / NA, F/#, Exit aperture - when are they non-intuitive?

Numerical aperture (NA) $= sin(\theta)$ where $\theta$ is the half-angle (see: http://en.wikipedia.org/wiki/Numerical_aperture) F/# $= \frac{f}{D}$ (same reference as above) where F/# is the ...
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73 views

What happens to light at sharp points? [closed]

At the tip of the sharp point shown, what will happen to light incident on it. This curiosity was invoked by a friend and also my childhood of watching shiny pointed swords in cartoons. Original ...
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105 views

A beam of light, traveling around a planet

Some time ago, I happened to have found one problem: The refractive index of the planet's atmosphere decreases with height above the surface under the following law: $$n=n_0-\alpha h$$ ...
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615 views

Magnification of an astronomical telescope not in normal adjustment?

I am stuck on this question: A telescope consists of two thin converging lenses of focal lengths 100cm and 10cm respectively. It is used to view an object 2000cm from the objective. What is the ...
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115 views

Why is optical orbital angular momentum (OAM) called “topological charge”?

The terminology "topological charge" is frequent in lots of research papers related to optical vortex or optical OAM, it is used to represent the optical OAM. Why? How to comprehend it?
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65 views

Effect of water on an image

I am stuck on this question: "consider the image above, P is an opaque disc (lying in a glass beaker) illuminated from bellow by a source S. A converging lens L forms an image of this at Q. Explain ...
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123 views

Optical absorption in a semiconductor for $E<E_g$ [duplicate]

Quoting from Solid State Electronic Devices (by Ben G. Streetman and Sanjay Banerjee): A photon with energy less than $E_g$ is unable to excite an electron from the valence band to the ...
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2answers
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does the positon of the virtual image change when I change position?

I placed a box in front of a plane mirror I looked at the image and smudged a bit of Vaseline on the mirror as a mark to indicate where I thought where the virtual image was. After that, I ...
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96 views

Increase contrast on the image taken by CCD camera

I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume ...
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1answer
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why does the optical media have different refractive indices?

Optical density is a measure of the refracting power of a medium. In other words, the higher the optical density, the more the light will be refracted or slowed down as it moves through the medium. ...
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Optical signal filters

Are there any optical filters which filter the signal's frequency and not based on the wavelength of the light? So what I mean is, if I have a modulated/pulsating light signal riding on a large DC ...
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98 views

Speed of light and distance

Our measure of distance (the meter) is defined in terms of how far light in a vacuum travels in a specific time. When light travels through another medium, we say it travels at a different speed. Why ...
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148 views

Drawing Ray diagrams

When drawing ray diagrams for concave mirrors, I was advised to : draw a ray that is parallel to the principle axis, the reflected ray will pass through the focus Draw a ray through the center (C), ...
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110 views

How to understand “the speed of propagation of the condition of constant phase”?

I still can't understand that the phase can be a constant until now. If the phase is constant, from the $$y(x,t) = a \times \sin(phase)$$ the shape of wave will be a line parallel to x-axis.But I ...
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1answer
305 views

Making fire using a filled water bottle

I have seen videos where a fire was started using a water bottle filled with water. I guess the bottle acts like a convex lens that converges light to a focal point to start a fire. But why does water ...
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1answer
101 views

Why aren't train headlights brighter? [closed]

I suspect a valid scientific, physics answer for this question, because I'd venture that train, insurance companies would've calculated and contemplated this question. Yet the train headlights at ...
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2answers
235 views

Resolution of the Eye-Light Rays and Diffraction

Please look at the problem. The problem is solved for me. However, I don't understand why the angle alpha is considered to stay constant when the rays go through the lens. The ray along the ...
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253 views

What are some good resources for learning photonics?

Including the generation, transmission, modulation, signal processing, amplification, and detection/sensing of light, I am interested in getting a good understanding of photonics. Does anyone have any ...
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What is a good textbook to learn how to ray trace light through an optics system in 3d? [duplicate]

I can do 2d problems easily, but I need to learn more to do a 3D ray trace. Can you guys point me towards a textbook? I'm having trouble dealing with the normal and incident rays in 3D