# Tagged Questions

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### Magnification confusion?

If I were to magnify the sun into a spot using the magnification formula of h/h'=-i/o would I use h to be the diameter of the sun which is given, or would I use the radius? Where half of the sun is ...
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### Calculating the Diameter of Jupiter through Image [closed]

I was trying to calculate the diameter of Jupiter from a picture I took of it. Here's the information I was able to get that I needed to calculate the diameter: Focal Length of Telescope: 1.2 m ...
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### Why do smaller wavelengths image particles more clearly when the particle size is already big?

Yesterday I scanned an ultrasound phantom that had cylindrical inclusions (1.5mm diameter). When I boosted the ultrasound frequency from 3MHz to 4MHz, these inclusions became much more clear. I ...
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### How does the area of illumination affect the numerical aperture / optical resolution of an optical system?

I have been reading an optics paper in which they designed a microscope with the following setup. A light source passes through a small pinhole, illuminates a sample, which then forms a diffraction ...
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### The MRI signal: why do we consider the phase in the MRI signal

I am trying to understand the imaging principles behind MRI and I was looking at some lecture slides found here Specifically, I am looking at slide 41 where we look at some of the equations regarding ...
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### What is the shape of the MTF curve in coherent imaging?

For incoherent imaging, the shape of the diffraction-limited MTF curve would look roughly like a triangle, with normalized contrast starting at 1 for zero spatial frequency and decreasing to 0 at the ...
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### What is a Light Efficient System?

When reading this paper, I encountered this sentence on the sixth page: When used in conjunction with wide-field microscopy, iterative restoration methods are light efficient. This is most ...
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### Wavelength for imaging an ultracold atom?

I was reading Stamper-Kurn's article Experimental Methods in Ultracold Atomic Physics (link). In the imaging section (page 13), he mentions: Cold atoms are conventionally probed by optical imaging....
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### theoretical echo from a point scatterer

How can I compute an echo coming back from a point scatterer? Let's say I know the excitation signal (plane wave), scatterer position, medium properties, what else do I need to see, how the echo will ...
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### What is the difference between a coherent and an incoherent imaging system? [closed]

Could this please be explained in terms of an abstract system and then an imaging system?
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### why shadows become dark when light intensity increases? [closed]

I observed following phenomena today: in my room with some lightings, there is a stuff toy placed in front of a wall. The ambient lighting doesn't cause any shadow on the wall currently. Scene 1: ...
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### What is the difference between scattering and backscattering?

I sometimes hear people talking about scattering and backscattering, but I really cannot distinguish between the two? Can some one please explain what is meant by these two concepts from a physical ...
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### Encoding multiple images in 1 beam

I am doing some research involving geometric optics. I need to reduce an image in size so it fits a rotating mirror we are using. I came up with the idea of projecting the focal plane on the mirror, ...
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### Why aren't pictures of Pluto darker than those of other planets?

Just as the intensity of the light from a candle decreases with distance, I would expect the light from the sun to illuminate the distant planets less than the closer ones. However, the pictures of ...
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### Law of refelction for electron-metal interactions?

I was reading 'Webb's Physics of Medical Imaging' which had a diagram very similar to the following in it: The interaction not the electrons with the anode creates x-rays. This diagram indicates ...
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### Searching for a textbook on Imaging

I'm hoping someone can recommend a book that will cover the physics involved in optical range image capture. I have a degree in physics, so I am looking for something on the technical end. To expand, ...
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### Thermal Imaging reflection?

I was viewing a youtube video that was about thermal imaging and saw something that caused me to ponder but I couldn't figure out an answer and the one assumption I have I don't know if it's correct. ...
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### How can I determine spatial resolution from an Airy disk diffraction pattern?

From introductory optics, the angular resolution of a lens (in radians) can be described by the Rayleigh criterion: \begin{align*} \theta = 1.220 \frac{\lambda}{d} \end{align*} This has its ...
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### What's the difference between two types of diaphragms?

What's the principal difference between aperture iris diaphragm and field iris diaphragm?
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### Imaging and the Electric Field

In this book (pg. 162), it mentioned that conventional lenses only focus propagating waves, thereby creating an imperfect image. In contrast, superlenses focus both propagating and evanescent waves, ...
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### Determining the spatial imaging resolution based on a pinhole diffraction pattern

I aimed a 780 nm/1mW laser at a 1Î¼m pinhole and took a picture of it using a lens and a CCD camera. The magnification of my imaging system is ~25 times. I wrote some code that takes the image of the ...
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### Inverse problem for MRI imaging

Background: Recently, I read a paper describing the existence of what are known as "concomitant gradient fields" in MRI. When a linear gradient is applied along one axis, concomitant gradient fields ...
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### Took a picture of my laptop screen with my iPhone. The blue pattern in the image seems to magnetic lines. How is this possible?

The pattern seems consistent with the magnetic force lines of a bar magnet.
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### Can a virtual image created by a mirror have position in front of the mirror?

I dont think so, because then the rays will intersect and the image will be real. Please let me know if you know a case in which a virtual image is formed in front of the mirror.
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### 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 .
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 + \...
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### 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 ...
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### 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 ...
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### 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 \$...
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### 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 ...
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### 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?
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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.
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### 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 http://irwincur.tripod.com/...
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### 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 ...
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### 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 ...