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 subwavelength objects can not be seen with optical microscope?

What would happen if we would take a very small sphere around 200nm diameter and try to detect it from the most efficient optical microscope? Technically, the Rayleigh diffraction limit prevents the ...
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21 views

Metal Refractive index

I'm working on Fresnel equation for calculation of reflection of a light (532 nm) on Iron. I've got a question: Is metals refractive index always a real number or it can be a complex number?
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193 views

Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...
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9 views

Cumulative Aberrations of Two or More Lenses

Suppose I have two lenses, and I can analyze and determine the Zernike aberrations coefficients of both lenses together in a given setup, and also the coefficients of one of the lenses seperately. ...
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What criterion did Abbe use?

For a microscope (correct me if I am wrong) the Rayleigh Criterion gives us: $$ R=\frac{1.22 \lambda}{NA_{condenser}+NA_{objective}}$$ But with the Abbe diffraction limit: $$ ...
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83 views

Luminance from multiple light sources

I have a LED diode: Given Luminance intensity [I] of $1.85$ cd. I want to have Luminance [B] from the light source of $75 \ {\rm cd/m^2}$. From $B=I/S$, where S is light source plane area, I get ...
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25 views

Light Intensity after refraction [on hold]

I have a bottle of water and I wanna measure the intensity of sunlight in different angles of sun radiation over the horizon (after refraction). Could you help me? radius of bottle : 5 cm Refractive ...
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Optics - Photodiodes - minimum photon energy that a photodiode will be sensitive to [on hold]

I'm foraying into the world of photodiodes, and I'm trying to calculate the minimum photon energy required for the photodiode to be sensitive to. Symbolic expressions desired. Minimum detectable ...
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24 views

Diffraction in Circle of light? [duplicate]

I'm working on a project that refers to optics. the question says when a laser beam is aimed to a wire ( perpendicular to the surface ), a circle of light then will be seen on a the surface. I somehow ...
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1answer
98 views

Diffraction and $k$-space

Regarding diffraction I am a little bit lost reading about reciprocal space and the space of $k$'s. As I understand it the Fourier relationship between a wavepacket $\Psi(\vec r,t)$ and the complex ...
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Model of scattering in wet things

You know that clothes and some surfaces become darker when wet (covered in an earlier question: why wet is dark?), because of the disordered reflections or of the refractive index of water or ...
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Why does a laser beam diverge?

I was wondering why a laser beam diverges. If all the photons are in the same direction, I would imagine that it would stay that way over a long distance. I am aware that a perfectly collimated beam ...
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Focusing and collimating laser light on a table top scale

I am looking for a summary of practical methods of focusing and collimating laser light, which I guess are contradictory objectives, or are they? For example, when I use typical small diode lasers, ...
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Could laser speckle patterns be used in diagnosing vision defects?

At the London Science Museum some years back, I saw a device which projected a laser speckle pattern and had a sign explaining that it would appear stationary for people whose eyes were correctly ...
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92 views

When (or what is the meaning of) $I \propto E^2$?

For a monochromatic plane wave: $$\mathbf E = \mathbf E _0e^{i(\mathbf k \cdot \mathbf r -\omega t)},\qquad \mathbf H = \dfrac{\mathbf B}{\mu _0}= \mathbf H_0e^{i(\mathbf k \cdot \mathbf r-\omega ...
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22 views

Significance of colours in photoelasticity

I already checked similar question at Physics SE, but none gives me a clear answer, also it is a bit difficult for me to understand it from wikipedia as I couldn't find relating material to my ...
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320 views

Magnification in compound microscope

I was studying about compound microscope here I don't see why we multiply linear magnification of objective with angular magnification of eyepiece. Shouldn't it be both angular or both linear? Can ...
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1answer
60 views

Do off axis sources produces the same diffraction pattern as on axis sources?

Let's say I have a simple lens and I am viewing two sources of light A and B through this lens. A is on the axis and B is not as shown in the digram below. Will A and B produce exactly the same ...
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What is the Index of Refraction of the Liquid Varied with wavelength listed in the question [closed]

A point source of light sits 0.5m below the surface of a liquid. The source produces a mixture of equal intensity red and blue light. The index of refraction of this liquid varies with wavelength ...
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Image formed by Refracting light

A jellyfish is floating in a water-filled aquarium 1.33 m behind a flat pane of glass 4.30 cm thick and having an index of refraction of 1.5. (The index of refraction of water is 1.33.) Where is ...
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Frequency difference of absorbed and emitted photons?

In a transparent medium, how does the frequency of incoming light compare to the exiting light? I thought it was the same, but doesn't there have to be an energy difference in two electron states in ...
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1answer
99 views

Apparent depth and virtual image position

Why does the virtual image appear right on top of the object and not a little to the right, for example? Is it explained by some formula or just symmetry of the geometry?
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1answer
25 views

Refraction of light marching band analogy

When trying to understand the refraction of light when it hits a slower medium, lots of people seem to be enlightened by the 'marching band' or 'marching soldiers' analogy, which 'explains' that when ...
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Options to correct rectangular laser beam profile?

We recently switched to a 405 nm laser diode which has a terrible beam profile -- it is a well-defined rectangle with an aspect ratio of about 10:1. The image below shows the collimated beam which ...
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Constant part of a photo taken [closed]

(56th Polish Olympiad in Physics, II stage) A photographer has a camera with a lens of focal $f$ with can be set to a value from the interval $[f_{min}, f_{max}]$. The diameter of the diaphragm is ...
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63 views

How we can calculate the elements of the Mueller matrix?

Disregarding coherent wave superposition, any fully polarized, partially polarized, or unpolarized state of light can be represented by a Stokes vector; and any optical element can be represented by a ...
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Does the Abbe limit hold for a single lens?

Let us say I have a single (converging lens) could I use the Abbe diffraction limit (for a microscope) to find its resolution or do I have to use the Rayleigh criterion. (i.e. Is the Abbe diffraction ...
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Any suggestion of laser pointer for everyday life study of fluorescence?

I want to buy a laser pointer to study fluorescence in my kitchen. Any suggestion? What kind of laser pointer? What stuff for demonstration?
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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 ...
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1answer
34 views

Limitations of (non-lightfield) near-eye displays

The answer to Is it possible to blur an image in such way that a person with sight problems could see it sharp? suggest that you cannot present a "counter blurred" out-of-focus image such that it ...
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1answer
70 views

Can a nuclear bomb be used as the power source for a laser beam

My previous post "Using nuclear bombs to detect near earth orbit objects" asked about using nuclear devices to detect Earth directed asteroids and low albedo comets. Now I want to explore a method of ...
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1answer
38 views

Light absorption according to “Beer-Lambert” law [closed]

Beer-Lambert equation tells us the measure of absorption of light when it enters to a liquid and comes out from the other side. But I have a question there: Suppose a glass that filled with water. ...
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Beating the Diffraction Limit with NSOM

I am trying to understand exactly why we can beat the diffraction limit when using near-field scanning optical microscopy (NSOM). For those who aren't familiar with NSOM, check out this article: ...
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66 views

Can the insertion of impurities (doping) influence optical properties of ZnS?

I am currently trying to simulate a scintillator system with silver doped zinc sulfide (ZnS:Ag). To simulate the propagation of photons inside the crystal accurately, optical properties like index of ...
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58 views

A Circle of light

I'm working on a project that refers to optics. the question says when a laser beam is aimed to a wire ( perpendicular to the surface ), a circle of light then will be seen on a the surface. I ...
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1answer
37 views

Light absorption for different liquid

when I was working on a cylindrical glassy bottle that filled with water, I found that the initial light intensity is less than the final light intensity. (It's clear but I experiment this) This is ...
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1answer
56 views

What happens if light is trapped between two points?

The image can explain my question In the image light is clearly trapped.Even if the mirror absorbs energy the light is continously being added, will there be enough force to break the mirror?
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65 views

Fresnel lens/kinoform: How to model diffraction at the edges of zones?

I would like to find the intensity distribution of light due to the diffraction at the edges of zones on Fresnel lenses or kinoforms. (That is, location of orders, heights of maxima, etc.) I can't ...
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Fresnel coefficient

I dont think I have enough backgrounds for optics. I am sorry for asking this elementary question. I am reading a paper Phyc Rev A, Vol 59 # 6, 1999 they introduces discontinuity matrix ...
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30 views

Can virtual reality goggles have focal point 20 feet away?

Can virtual reality goggles have focal point 20 feet away? I read that eye strain from computer screens occurs if the eyes spend too much time looking at a screen that is too close. The 20-20-20 ...
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1answer
58 views

James Bond and the invisible car [closed]

For a seminar paper with the topic "Illusion of Invisibility in the James Bond movies" I have to investigate, whether the invisible car from "die another day" is (at least from a theoretical point of ...
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1answer
20 views

Why does light reflected on water tends to 'smear' in the vertical direction? [duplicate]

I have noticed that in city lights reflected on the water are very often smeared more in the vertical direction (relative to the reflecting plane I presume), than in the horizontal direction. See, for ...
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2answers
385 views

Finding the illuminance from a triangular light source

Since most light sources in games are point-like, it's pretty difficult to approximate area light sources with point sources. As triangles are a universal form to represent 3D models (thus area light ...
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Why does the chief ray not bend like other rays at the optical axis but goes straight?

1 pg In this picture the chief ray is not bending which is going through the optical axis. It passes straight while other rays from the same object are refracted because they change the medium.
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When does the wagon-wheel effect occur?

Sometimes you see a video of a fan or a propeller spinning very fast, and the apparent rotation is distorted. The fan can appear to be moving in the opposite direction of rotation, or even stationary. ...
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Resolving power of a diffraction grating?

I was working thru a derivation of the resolving power of a diffraction grating at the $n$th order. Here is that derivation: Let us say we have a diffraction grating width $W$ and are looking at ...
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1answer
32 views

Non resonant modes in cavity

I have a simple question. Suppose we have a laser with a cavity such that the frequency of the light that the laser emits does not match with any longitudinal modes allowed by the cavity. In ...
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1answer
27 views

Is it possible to implement the reversed dispersion of a white light beam and how?

The dispersion of white light beam while passing through a triangular prism is well known. Considering the reversibility of optical path, it should be possible to reverse the experiment. How can ...
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What is the difference between the words transparent and translucent?

Merriam Webster defines transparent as: Having the property of transmitting light without appreciable scattering so that bodies lying beyond are seen clearly. And translucent as: ...
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Michelson interferometry - is a compensator plate necessary?

I am studying the Michelson interferometer shown in figure 2 (similar design shown below) of the AMRITA vlabs tutorial. There it is stated that Since the reflecting surface of the beam splitter ...