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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Ways to measure the focal length of a convex lens with only natural sun light [closed]

What are the common ways to measure the focal length of a convex lens with only natural sun light?
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Mirrors and the human eye

Not sure if this is a suitable question for this exchange. Me and a friend are debating what can be seen through a periscope consisting only of two 45 degree mirrors. My friend tells me that the ...
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126 views

Gaussian beam modelling, location of the beam waist?

In reference to the specifications of a laser diode below: http://www.thorlabs.de/thorcat/11900/L780P010-SpecSheet.pdf I wish to be able to model it as a gaussian laser beam. I understand there is a ...
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71 views

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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Thin Lens Methods and Object Perceived vs Literal Size

When using the ray trace methodology to solve a given thin lens question, does the arrow (commonly used as the example object when tracing) represent the literal height of the object or the perceived ...
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314 views

Image formation at surface of water

Consider a lake full of water which has an object immersed in it. Now, if an observer was at the surface at a sufficient distance so that the light ray from the object is internally reflected, should ...
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124 views

Layer thickness measurement

I am interested to measure the thickness of the coating on a mirror (e.g. in the picture below). What are the available and best way of measuring it? What will be the solution in case of multiple ...
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7k views

What is the near point for the eye

So I am a teaching assistant for an introductory physics class. One of the problems on this weeks workshops is: Where is the near point (far point) of an eye for which a contact lens with power of ...
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127 views

Graded Index fiber

In the following picture of a graded index fiber two different modes are depicted. One is a higher mode which is propagating towards the core-cladding interface and one is through the higher ...
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Which microscopy technique is for wet condition? [closed]

I am searching for a microscopy technique in wet conditions. It must be possible to see through the specimen. ESEM is good but can't see through. TEM needs high vacuum which will boil away water. The ...
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70 views

Optics & Law of Cosines

I'm supposed to use law of cosines on $S_1S_2P$ in the following diagram that relates to a lens: To arrive at the following equation: $$ \frac{r_2}{r_1} = [1 - 2(\frac{a}{r_1})sin(\theta) + ...
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Reflection formula for spherical surface from Fermat's principle (Query)

The snip shows a part of the method shown by my teacher, to describe the reflection formula for spherical surface. However I do not understand how the relation of AB and BI (which I have ...
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246 views

Formation on image on screen?

When we first learn elementary geometrical optics, the first thing taught to us is the two broad divisions of the type of reflection.-Regular and Irregular or Diffused. The difference in cause for ...
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530 views

Conservation of energy with Huygens-Fresnel principle

I am currently experimenting with Huygens-Fresnel principle. I am trying to simulate the propagation of a beam, emerging from an aperture slot of width w. I assume the slot to be long and therefore ...
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103 views

Is this diagram, concerning Young's double slits, inaccurate?

"This diagram" : My question is whether those lines (interference) have to originate from a single point. The diagram used to demonstrate what $m$ (path difference) means, has two lines originating ...
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25 views

How to polarize a laser beam

I'm working on an optic project that I need my laser beam to be polarized. Do you a simple way to polarize my laser beam?
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62 views

Huygen's principle and why can't we see atoms with light

First of all, I'd like to discuss Huygen's principle. In order to explain waves diffraction, it says that every point in a wave front behaves as a source, so the next wave front is the sum of all ...
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Would the Hubble Space Telescope be of benefit for optical astronomy at Lagrangian L5 point?

The Hubble Space Telescope will enter a decaying orbit in 2024. This is a physics based question, so I don't want to get into the engineering details more than necessary. Just for background, the ...
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66 views

Combination of two concave lenses

When we have two convex lenses in contact we have the combination behaving as a converging lens. Can someone please give an analytical description for the combination of two concave lenses in contact ...
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Would obstacles cause light diffraction if it has the same refractive index as the surrounding material?

Restatement of title: Would an obstacle still cause diffraction of light if it has the same refractive index as the surrounding material?
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What is the formula of power of an optical instrument?

I have searched and found that the power of a lens, with surrounding medium of refractive index $n$, is $n/f$ where $f$ is the focal length, the formula is $$n/f=(n'-n)/R1 + (n-n')/R2.$$ But in my ...
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A very basic question about optics and figuring out focal length

Focal Length of a lens - I was told that as an approximation I could simply put a sheet of paper with text on it on a table, hold the lens above it, and when I can see the text most clearly, the ...
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144 views

How do you calculate the focal point location of a circular mirror? [closed]

I'm trying to find the focal point and center of curvature of a concave mirror. Just using the radius for the center doesn't seem to work. I know C = 2f, but I'm not sure how to find f or C, given the ...
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329 views

How to convert candela into joule?

How to convert candela into joule? What equation can we use? Is this site useful? http://en.wikipedia.org/wiki/Photometry_%28optics%29
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155 views

Light intensity units in Beer-Lambert law

I have always found the Beer-Lambert law written in terms of light intensity, but what are the units of that light intensity? When related to light, some people talk about cd, or W/cm/cm... What are ...
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188 views

Proving susceptibility in Lorentz Model satisy Kramers-Kronig relations [closed]

My instructor asked me to prove that the real and imaginary parts of the electric susceptibility derived from Lorentz Model satisfy the Kramers-Kronig relations using the residue theorem. The problem ...
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62 views

Image angle illusion [closed]

I am not sure whether this question on-topic here. (please suggest to migrate if this is off-topic) What is the phenomenon/illusion (or something else?) known as where in a photo of a person, the ...
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How to determine the difference between object distance and image distance? [closed]

How do we derrive the last equation? Whatever I tried it didn't work... Oh man I just saw, that all the did is write $b=3m-g$, how was is it possible for me to miss it...
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122 views

Missing factor of 1/2 in the definition of light intensity

The light field can be written as $E=A \cos\theta$ where $\theta=kz+wt$ is the phase of light wave. What we measure or see is the intensity which is the square of the light field $$I=E^2=A^2 ...
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43 views

Lowest detectable power of a laser?

What is the lowest power of a laser beam which is still detectable? More precise: If the intensity of my laser beam is reduced by a factor of $10^{-8}$, can I still detect it? Of course this depends ...
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286 views

On solving a two lens system

A common method to solve for the image formed due to a two lens system consisting of two thin-lenses separated by a distance is: Locate the (intermediate) image formed by the first lens, ignoring ...
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68 views

Diffraction and Shape in the grating

Suppose, I use a laser with a known wavelength of 650 nm through a "opaque grating" that has a pattern of holes of same shape and size. We can see the pattern on the screen. We know the distance ...
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71 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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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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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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58 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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77 views

Difference between single mode and multi mode optical fibres?

What is the difference between single mode and multi mode optical fibres? First off, I guess that by modes we mean the spatial modes of the electric (or magnetic?) field right? Now: what makes a ...
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Electric Field and Magnetic field of Guassian beam [closed]

The center of the gaussian beam in glass has a beam power of 1 mW and a beam radius of 20 μm (micro meter). The wavelength of the light $\lambda_0$ is 1550 nm. How can I find the electric field E ...
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Fate of light ray

This question has been on my mind since I first learned optics. Where will the light ray go? First, I thought of it taking a U turn. But, I don't think that will happen. Now I have studied a bit ...
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98 views

Polarization effects of second-harmonic generation (SHG)

In one of my labs, we were using an Nd:YAG at 1064 nm and we put it through a KTP nonlinear crystal to perform SHG. We noticed that before the crystal, the 1064 light was unpolarized, but the 532 ...
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410 views

What are the 'oscillators' in the Drude Lorentz model?

Jackson's Electrodynamics defines the Drude-Lorentz model as a set of harmonic oscillators (running over indices $j$ below), which, if you write out the equations of motion and rearrange a little, ...
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552 views

Photoelectric effect: current vs wavelength

In an experiment where the type of metal,intensity of light and potential difference across a battery is kept constant at 2V the results show that an increase in wavelength, obviously in turn ...
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290 views

Cylindrical Fresnel Lens Focus Problem

How to focus beam from the fresnel lens on a flat surface. In my case, instead of producing the light beam, I am receiving the light beam. So, the beam comes from the right and then focuses at a ...
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36 views

Query regarding interference

In Young's Double Slit experiment, why is it that two waves vibrating perpendicular to each other doesn't show interference? I know that for interference to happen, the waves must be coherent ( i.e., ...
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Microscopic origin of optical transmission

When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy ...
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478 views

Is it possible to project an image onto water? [closed]

Is there a way to create an image/projection in the water? Or form the water to project an image, little dot/pixel? Use some type of frequency to modulate the little dot in the fluid?
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314 views

Refraction through prism

We know that the light gets refracted when it enter a medium low/high refractive index. But why light is not refracted when it comes out from the vertex of a prism.
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143 views

Beam focused through lens at an angle

Under normal lens operation, a beam is sent through the centre of the lens along the optical axis (ie perpendicular to the lens's plane). What happens when a beam is sent through a lens at an angle to ...
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297 views

Diffraction/Bragg's law : how does $2\theta$ come about?

I'm trying to get my head around a problem (I should have checked whether I had the answer in class, the exams are coming up now and I don't know if I'll get a lecturer response over the holidays) I ...
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Relativistic aberration - half-sky radius

With relativistic aberration, a sky full of stars gets concentrated in the direction of motion. As a rough measure of the degree of concentration, one could use the radius of a small circle, centered ...