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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Batman spotlight in the sky

I have noticed that obstructing a spotlight typically results in a blurred shadow unlike the crisp batman symbol in the comics of batman. Is there a way to create a spotlight with a crisp batman ...
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4answers
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What really cause light/photons to appear slower in media?

I know that if we solve the Maxwell equation, we will end up with the phase velocity of light being related to the permeability and the permittivity of the material. But this is not what I'm ...
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1answer
162 views

Does 'ring' diaphragm reduce lens spherical abberations?

As I see it, as light comes through approximately same angular area of the lens, it should have less aberrations, and at the same time, it should still have high θ -> diffraction limit should stay as ...
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2answers
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How to find the principal point in an image?

I need to find the principal point in an image. Its a point where the principal axis intersects the image sensor. Due to misalignment this point is not at the center of image always(or image sensor). ...
5
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2answers
354 views

How to place a mirror parallel to a wall?

For one of my experimental setup I need to place a mirror perfectly parallel to a wall. It can be placed at any distance from the wall. I would like to use any method other than direct measurement. I ...
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2answers
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How do you calculate the intensity of light around the focal point from a focused collimated beam of light?

Problem/Purpose of me asking this question to you people who know more than me: So I'm doing a science project where I'm collimating a beam of light to a focus point in a light medium (water vapor or ...
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1answer
182 views

What software can I use to simulate supersonic gas particle flow? [closed]

Please please help me out with this. I am trying to find a software/program that I could use the simulate the scattering effect of light when it strikes gas particles moving at supersonic speeds? ...
2
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3answers
2k views

How could I translate a field of view value into a magnification value?

When I zoom in with Stellarium, it indicates a field of view (FOV) value in degrees, but most binoculars and telescopes are advertised with value like "nX magnification power." How could I translate ...
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1answer
405 views

Lens design - max lpmm, monochromatic light

How can I approach this task: I need to design diffraction-limited lens for monochromatic light (~1nm line width, so I guess no need to correct chromatic aberrations), geometry aberrations are also ...
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2answers
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Calculating diffraction-limited resolution for a lens setup

Supposed a lens arrangement is prepared where light from an object is collimated, focused and recollimated etc. before entering a CCD array. Given that we can calculate the diffraction-limited ...
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0answers
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What properties of certain plastics make them x-ray transparent? [closed]

I was blown away by the abundance of good info here, and I thought maybe you could help me out with this query. I am in the process of developing a product, and I need to find a clear plastic resin ...
9
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1answer
965 views

Why is the Ritchey–Chrétien telescope preferred in professional astronomy?

Hubble, as well as numerous other professional telescopes, use the Ritchey–Chrétien design. What optical and instrumental advantages does this kind of telescope have for professional astronomy?
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2answers
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intensifying a light source

When trying to intensify a beam of light by refracting it through a lens, (as in a lighthouse fresnel system or similar railroad style switch lamp from years past), is the beam intensity increased by ...
9
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4answers
845 views

What are the various kinds of Cassegrain telescopes, and what benefits and drawbacks does each have?

Many hobby or amateur telescopes are of the Newtonian design, but most of the professional telescopes that I know about are some kind of Cassegrain (a very specific kind, I believe). In general, ...
2
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2answers
2k views

Michelson rotating mirror experiment

Could someone explain the calculation required to answer this question. It is from a text book and the answer is recorded as 585Hz but I cannot replicate the answer. In 1931 Michelson used a ...
3
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2answers
252 views

Intrigued about a polarizer effect

This comes from one of my physics course at university (many years ago!), I hope I recall it right. We were studying optics, and were given some polarizer filters to experiment. They were disc- ...
6
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2answers
300 views

What makes a good set of binoculars? [closed]

After trying a bunch of binoculars at Star Parties and the like, I have a pretty good feel for about what aperture and magnification I'd like in a new set binoculars. I'm an eyeglass wearer so a long ...
22
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3answers
2k views

How to determine what size telescope to buy

A couple of years ago my son showed an interest in astronomy and we bought a 6" reflector telescope. We use it pretty regularly and have enjoyed it immensely. Lately we've both been wishing we had ...
6
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2answers
633 views

Optimal Angular Field of View (AFOV)

Given the rather huge price differences between eye pieces at the same focal length. How exactly does the AFOV affect the view seen through the eyepiece? Are higher / lower AFOV better for certain ...
3
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3answers
5k views

How do laser rangefinders work when the object surface is not perpendicular to the laser beam?

I find the functioning of a laser rangefinder confusing. The explanation usually goes like this: "you shine a laser beam onto the object, the laser beam gets reflected and gets back to the device and ...
7
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1answer
101 views

What is a backlit CCD sensor, and why might I prefer it to other kinds?

I've heard Astronomers talking about backlit CCD sensors, and talking about how much better they are than other types. What are they, why might I want to get one, and what are the pros/cons of this ...
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5answers
2k views

Focusing Light with Flat Mirrors

What is the best way to focus (sun)light using flat mirrors? My goal is to start a fire. Cutting the mirrors is easy.
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3answers
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Observing lunar lander and footprints on the moon?

After Apollo 11 first landed on the Moon in 1969, there have been conspiracy theories that this never really happened and that it was all a hoax. In 2010 NASA released photos from its Lunar ...
2
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2answers
63 views

What objects look best in an O-III filter?

I've heard that an O-III (Oxygen III) filter is great for planetary nebulae. Is this true for all planetary nebulae, or just some or most? What other target types are often improved with an O-III ...
10
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3answers
232 views

Why is M42 red in the pictures, but green when observed at the eyepiece?

I saw magnificent images of the Orion Nebula (M42) in pictures from Wikipedia, However, when observed with a telescope, the nebula appears green hued, and I can't see any of the characteristic red ...
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6answers
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Lenses (refractor) or mirrors (reflector) telescope?

What differentiates, in terms of practical quality, not technical implementation, a refractor from a reflector telescope? Why would one prefer a refractor over a reflector, when reflectors come with ...
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4answers
8k views

What does f/4.6 mean in a telescope and how important is this value? [closed]

In some specifications for telescopes, I saw a value marked as f/4.6. What does it mean exactly, and how important is when it comes to choosing a telescope?
14
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4answers
42k views

Why does the road look like it's wet on hot days?

Often, I'll be driving down the road on a summer day, and as I look ahead toward the horizon, I notice that the road looks like there's a puddle of water on it, or that it was somehow wet. Of course, ...
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1answer
390 views

Light travels a straight line write down the principle in which this is manitested [closed]

Light traveles a straight line write down the principle in which this is manifested.
2
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1answer
746 views

Refractive index of organic solvents in near-infrared

I wonder if the refractive index of acetone, ethanol, methanol, heptane was measured in the range above 830 nm. The site refractiveindex.info provides it only for visible, and I couldn't find any ...
2
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1answer
415 views

direction of Pockels Effect. Refractive index eigendirections

There is a linear electro-optic effect called Pockels Effect The brief is that refractive index changes due to electric field. If there is an anisotropy (like birefringence) and electric field is in ...
12
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3answers
948 views

Can the speed of light become complex inside a metamaterial?

The speed of light in a material is defined as $c = \frac{1}{\sqrt{\epsilon \mu}}$. There are metamaterials with negative permittivity $\epsilon < 0$ and permeability $\mu < 0$ at the same time. ...
4
votes
1answer
694 views

Why can't I see far when I look in a mirror?

I'm myopic. It's a fact. I understand exactly how it works because Internet told me light rays encounter themeselves too soon in my eyes... that is why I can't see far objects even if I see near ...
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4answers
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How to get Intensity over a range of wavelengths from a Total Intensity

This is a theory vs experiment problem for me I think in that - as usual - I think I know the theory, but when it comes time to run an experiment, I can't actually extract squat. So, here is my light ...
5
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2answers
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How does Fraunhofer diffraction depend on the orientation of the sides of a lens?

Matt in his answer on What does a hexagonal sun tell us about the camera lens/sensor? mentions Incidentally the number of (distinct) points to the star is equal to double the total number of ...
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2answers
368 views

Do and can phone signals come inside AC car which is glass-packed

Can phone signals penetrate glass, so can I expect phone signals to come if I am sitting inside a closed AC car. Thanks,
6
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3answers
767 views

Recently publicized experiment on destructive interference between two laser beams

Recently I've had several non-physicist friends ask me, independently of each other, about an experiment where two collinear laser beams destructively interfere along a certain length. Everybody wants ...
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2answers
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Glycerol: refractive index & absorption spectra in 0.2-0.4um range

Could anyone suggest where can I find absorption spectra & refractive index of Glycerol? I am specifically interested in UV range, 200-400nm, everything I was able to find out was for standard ...
0
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1answer
169 views

Merge different wavelength rays

Let's say an array of rays of light is given. Each ray has a specific wavelength (in the range of visible light). Example: ...
6
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4answers
573 views

Far-field intensity from scattering of small particles

Howdy, I'm building a simulation for looking at the light field underwater. In order to verify my simulation, I'm looking for some data showing the far-field intensity that comes from single ...
4
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1answer
156 views

What's the name for taking pictures of air flow in a normal room?

There is a way to photograph air in a room. It makes convection, breathing and movement visible. The result looks a bit like a soap bubble. This is some kind of optical effect. No special gases or ...
2
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1answer
2k views

How does Telescope lens work?

1.How does a Telescope work? 2.What factors increase the magnification of the lens?
17
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6answers
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Are human eyes the best possible camera?

I am not a physiologist, but whatever little I know about human eyes always makes me wonder by its details of optical subtleties. A question always comes to mind. Are human eyes the best possible ...
5
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1answer
4k views

Newton's color Disk

How does Newton's color disk work? Newton's disk - Take a circular white color disk, make 7 equal intersections and paint section with respective VIBGYOR colors, now when you spin the disk in certain ...
4
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3answers
761 views

Virtual images in (plane) mirrors?

The following image is taken from teaching physics lecture Was man aus virtuellen Bildern lernen kann (in German): Now the cited paper claims that the left hand side is the correct picture to ...
6
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1answer
442 views

Where does the energy go, when light is blocked by polarisation

I've been looking around about LCD monitors, and how they polarise light. When a pixel needs to be black, the light is "twisted" so that it can't go through the polarising sheet in front. What happens ...
6
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5answers
425 views

Trapping a lightray

Given a solid whose interior is a hollow sphere with perfectly reflecting mirrors. A small hole is drilled in the sphere and a photon is sent in at some angle. Will it always eventually exit through ...
3
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2answers
469 views

If you are told an image is real and you know it was made by a single optic (either a lens or a mirror), which of the following must be true? [closed]

If you are told an image is real and you know it was made by a single optic (either a lens or a mirror), which of the following must be true? The image distance is positive. The image distance is ...
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0answers
564 views

Double Slit Problem, Waves and Optics [closed]

Given d(slit separation)= $0.158\:\rm{mm}$, $\lambda _{red}= 665\:\rm{nm}$, $\lambda _{g/y}= 565nm$, L(distance from screen)= $2.24\:\rm{m}$ What is the distance between the third order red and ...
7
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2answers
402 views

Fairly Broad Spectrum Light Source Options

I tried this sight before to find filtering options and got fantastic results, so let's try again! I am setting up an experiment that requires light of two different frequencies (445nm and 350nm). ...