The tag has no wiki summary.

learn more… | top users | synonyms

0
votes
1answer
25 views

Thick mirror produces number of images

Why is second image always bright ? This question is so often asked in mcat examination but I find no legitimate answer to it .
1
vote
0answers
12 views

Does there exists a flexible supermaterial with which you can write a “thermal image” instead of a visible light image [closed]

I'm thinking a mesh of copper that some how heats up at the touching points and you address each point with rapid switching. Would that not work? Also, what do you suggest as a heater at each of ...
1
vote
1answer
20 views

Optical interferometers resolution

I found this interesting list of optical interferometers: http://en.wikipedia.org/wiki/List_of_astronomical_interferometers_at_visible_and_infrared_wavelengths But I can't understand which is the ...
1
vote
0answers
56 views

Penetration and skin depth in 'metallic' magnetic induction tomography (classical electromagnetism)

Does anyone know how AC magnetic fields behave in 'metallic' magnetic induction tomography (MIT). Do they form a magnetic circuit around a metallic specimen or penetrate through it, or both? This ...
2
votes
2answers
118 views

Can a point source be located more accurately out-of-focus or in-focus?

Let's say I am taking a picture, and I know a priori that the image is of a single ideal point source of light at infinity. With a perfect imaging system in focus, the image shows an Airy disk. I ...
0
votes
0answers
10 views

Conjugated-Phase Matching

I am working on imaging applications of phase-conjugation in optics, in particular phase-conjugation imaging from recorded holograms. I have found several useful sources, but I cannot find a book ...
0
votes
0answers
16 views

Temporal coherence in Computational ghost imaging

In pseudo-thermal ghost imaging using a laser beam passing through a rotating ground glass plate, the temporal coherence is important since the intensities in both scanning and bucket detectors have ...
1
vote
1answer
50 views

Infinite plane wave and ray vectors

I want to clear my mind on one basic optics thing: If I have a point source some distance away from a lens, the position of the image formed can be found using traditional geometrical optics ray ...
1
vote
1answer
42 views

What type of interferometry set up do I need to image a small structure at a distance?

Please forgive me, optics isn't my forte. I'm trying to work out how to image the surface structure of an object at a distance. Considerations are: Monochromatic light- it must be imaged in the ...
2
votes
2answers
94 views

How to produce a loss-free combination of two “identical” beams?

This is for anyone with experience in optics/imaging/photography as well as anyone who likes to puzzle over tricky physics problems. As the title suggests, this is about combining two (for all ...
0
votes
1answer
26 views

Where does this formula for prediction of a multiple wave come from?

On the slide I am reading, it says this: Any surface related multiple can be construced of primaries: $\hspace{5cm}$Multiple = Primary$_1$ (green) + Primary $_2$ (red) $$T_2 = T_1 + ...
1
vote
0answers
62 views

3D Surface Related Multiple Elmination (SRME)

Let's assume we are looking at first order multiples of the same surface (i.e no peg leg, etc). I am looking at marine 3D SRME and I am a little confused as to how this works. I understand that in the ...
0
votes
0answers
72 views

How to calculate max/min Right Ascension and Declination in telescope field of view

I have a telescope with focal length 1200mm. My camera has 5184x3456 pixels with size 4.3um. This combination should give me a resolution of 0.74"/pixel and thus a field of view of 1.06° x 0.71°. ...
5
votes
5answers
443 views

do lenses with curved focal planes exist

I know about spherical, aspherical, cylindrical lenses, but are there lenses that could have a curved focal plane? for example, the retina of the eye is curved, and still we see sharp images of ...
3
votes
1answer
154 views

What's the significance of the definition of T1 and T2 relaxation times

In MRI we measure $T_1$ and $T_2$ relaxation times. $T_1$ relaxation time is defined as the time it takes for the longitudinal component of magnetization to recover $1-1/e$ of its original value, and ...
0
votes
1answer
2k views

X-ray imaging and diamond

Why doesn't diamond show up in X-ray imaging? Diamond is the hardest substance ever known, and as we know, X-ray radiation is produced when a cathode ray of high frequency hits a very high atomic mass ...
1
vote
1answer
320 views

Photo of reflection in magnifying mirror shows normal magnification. Why?

I just took a picture of myself in one of those magnifying shaving mirrors and in the photo I am unmagnified! Why is this?
9
votes
3answers
595 views

Can we make images of single atoms?

I was wondering how far in imaging physics had gotten. Do we hold the technology to actually take a picture of, say, an alpha particle, or even a single atom? I realise we aren't talking about camera ...
9
votes
3answers
416 views

Put a sensor at the focal length, behind, or in front?

My intuition tell me that at the focal length a convex lens all the light converges to a point. Following that logic, it would make sense to me that a camera chip would either need to go slightly in ...
12
votes
4answers
1k views

Usage of helium in MRIs

More and more articles pop up on the shortage of helium, and on the importance of it. Its usage in MRI's spring to mind for example. I looked it up and found out that helium is used for its 'low ...
2
votes
1answer
133 views

Peak deconvolution [closed]

I need some help understanding how much information I can pull out of this data. I have a sample made up of two materials. Materials A and material B. Then I took a picture of the sample. The two ...
4
votes
2answers
130 views

What is an extreme deep field image (XDF) and how is it captured?

NASA recently took this Extreme Deep Field image (XDF) that is the area of only small fraction of the dia of moon and contains 5,500 galaxies. Nasa says this was capture by extreme long exposures so ...
0
votes
1answer
913 views

How do Anamorphic images work? [closed]

I found the following anamorphic image on this site Can anyone explain the physics behind the working of such images? Can we create our own anamorphic images? If so how? Thanks in advance.
0
votes
1answer
44 views

Does an uneven and/or moving surface affect quality when using a solar filter?

I have chosen to make my own solar filter using Baader as opposed to Mylar or anything else based on these: http://physics.stackexchange.com/a/25204/6805 and ...
3
votes
1answer
1k views

How does a stronger magnet affect the MRI image quality?

In which ways is a stronger magnet better for magnetic resonance imaging? I read that: The field strength of the magnet will influence the quality of the MR image regarding chemical shift ...
2
votes
1answer
227 views

Curved lines in a picture (Photography)

My problem is when I take a picture (a close one) the straight edge looks a little curved. In a standard camera, like a CyberShot. I would like to know if there is some relationship between the ...
7
votes
4answers
302 views

How to guess the content of a christmas present?

Let us assume that the present does not make any recognizable sounds when shaken (meow splat - the present now contains a dead kitten). Let us furthermore assume ...
0
votes
1answer
74 views

How to determine the angle a camera has to be at to image a desired scene, given the camera parameters?

Reviewing old material I learned years ago, having a hard time rewrapping my head around the relationships in capturing images from a camera. Imagine a scenario with the camera placed on the ground ...
2
votes
1answer
182 views

How does the focal length of the lens change the distance from the camera to an object?

I am reviewing some old image processing notes and have the following problem: I have a camera with a projection plane of $2cm\ by\ 2cm$ and a $15mm$ lens. If you want an $1.5m$ object to take ...
2
votes
1answer
1k views

How to determine the field of view for a pinhole camera with given parameters?

I am reviewing some old material I learned years ago and am having trouble figuring this one out. Can somebody confirm that I have done my math correctly, and tell me how I can recover the field of ...
7
votes
1answer
34 views

Is There Reddening on Objects Other than the Moon Upon Entry into Earth's Umbra?

With the recent lunar eclipse, for some reason this question came to me: The reason the Moon turns red is that the only appreciable sunlight hitting it when it's in Earth's umbra is refracted through ...
6
votes
1answer
76 views

Detecting dim objects

What are the minimum conditions (switching times, sensitivity ...) for a camera to detect dim objects, e.g. Oort cloud or Kuiper belt objects, passing by in front of a star in the background? I've ...
5
votes
1answer
77 views

Shadow of a Jovian moon over the Great Red Spot

Where can I find pictures of the shadow of any of the Jovian moons partially covering the Great Red Spot? A series of such pictures over time would even be better. The idea is to learn more about the ...
3
votes
2answers
428 views

why isn't the variance of Fano noise proportional to the number of photon arrivals?

I've been reading "Photon Transfer" by James Janesick and in Chapter 3 (http://spie.org/samples/PM170.pdf) he describes the various sources of noise in a CCD. Basically, incoming photons interact with ...
2
votes
1answer
337 views

How to determine the required resolution to view an image at a certain size?

If I have several camera specifics, can I determine the required resolution to view an image at the size I want? For example, let's say I want a picture of a square painting to be at least ...
8
votes
5answers
102 views

Exoplanet detection via space-based parasol

I remember from watching Cosmos years ago, Carl Sagan suggested an interesting hypothetical method for directly seeing exoplanets. He proposed that in the 'future' we could launch a satellite designed ...
5
votes
4answers
760 views

Optical explanation of images of stars?

Very often when viewing pictures of the cosmos taken by telescopes, one can observe that larger/brighter stars do not appear precisely as points/circles on the image. Indeed, the brighter the light ...
6
votes
2answers
153 views

PSF Measurements In Fluorescence Imaging

Quite a technical question! I have measured the Point Spread Function of 100nm fluorescent breads with my Olympus scanning head. I'm two-photon exciting the beads with a wavelength of 800nm and ...