Questions tagged [imaging]
The imaging tag has no usage guidance.
128
questions
2
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1answer
59 views
Plausibility of detecting viruses using optical spectra [closed]
Ok, this is a huge long shot, and I also apologise if this is a poor question (I'm a newbie here...). This doesn't seem to me a strictly perfect fit for Chemistry.SE, Biology.SE, or Photography.SE ...
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0answers
20 views
How to interpret the cross-spectral density of an incoherent field
I have been given a definition of the cross spectral density of a completely incoherent field:
$$W(x_1,x_2)=S_0\delta(x_1-x_2)$$
How do I interpret this? As I understand it, this means that there ...
0
votes
2answers
80 views
What kind of information does light carry so that brain can “see” shapes and distances of objects? [duplicate]
I know that we actually see with our brain in a way that eyes only absorb the incident light upon them and they transform some sort of information to the brain and the actual "seeing" is done by the ...
0
votes
1answer
34 views
Can this textbook question on angular magnification be answered without a ruler?
This is a textbook question on angular magnification from a chapter on optics and imaging. Note that this comprehension check comes before telescopes are introduced.
12 Figure 15.12 [below] shows ...
0
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0answers
21 views
How do modern microbolometer cameras measure absolute temperature of an object
I recently started working with thermal cameras and I was surprised to learn that they don't give you the temperature value of the object you are looking at for each pixel. So I did some reading. I ...
4
votes
3answers
227 views
Infinity Corrected Microscope Fourier Optics paradox?
I am analyzing an optical system two different ways. One way is using the image formation formula:
$$
\frac{1}{d_0} + \frac{1}{d_i} = \frac{1}{f}
$$
and the other is using the Fourier transform ...
0
votes
0answers
21 views
VMI image analysis
I used VMI for the photodissociation of O2 and I wonder how I can correlate the radius with the actual velocity of the fragments.
Thanks a lot!
0
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0answers
19 views
Reconstruction Problem for Result Matrix of Radon Transform and solving length of r from Multiplying of Attenuation Coefficient and r(or rho)
We've been on a project that given us in Medical Imaging Systems class about that Computed Tomography Simulation on MATLAB for 3 months. We are still going on comprehensive research on these all of ...
2
votes
0answers
74 views
Spot size for objective (not infinity corrected)
A fundamental axiom of imaging in optics is the resolving power of the lens system, which is directly related to the smallest possible spot a lens can form. For an ideal lens with a numerical aperture ...
0
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0answers
14 views
Fourier Representation of Camera (Telephoto) Lens and Propagating Light
Say I have a telecentric microscope objective with a source $S(\mathbf{u})$ sufficiently far away from an object that we can assume that the light incident on the object to be the Fourier transform of ...
0
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0answers
9 views
Consistency condition for exponential radon transform
The Radon transform can be written as $$p(\xi,\phi)=\int f(\xi,\eta)d\eta $$
The exponential radon transform can be written as:$$m(\xi,\phi)=\int f(\xi,\eta)e^{-\mu \eta}d\eta $$
The radon transform ...
1
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0answers
20 views
Transmission Spectrum of Rock
Maybe a very specific question, but what wavelengths are sand grains transparent to?
Also, how can one image underground minerals through rock? Is there a certain Infrared band that sandstone (...
1
vote
0answers
18 views
Velocity map imaging
I am a bit confused about the image reconstruction for velocity map imaging. As far as I understand, at the interaction point, ions are produced in a Newton sphere which gets projected on a 2D screen (...
1
vote
0answers
25 views
Location of diffraction pattern on the image plane/detector plane
I am trying to make a spectrometer. At the moment, I have an optical setup consisting of a laser, diffraction grating and a screen/detector in a straight line. I am trying to understand how to ...
1
vote
1answer
122 views
What would a lens-less world look like to us? [closed]
The images we perceive through our eyes are formed by focusing the incoming light with the eye's cornea and lens. The information is "captured" by the retina and then transmitted to our brains through ...
1
vote
0answers
48 views
Rayleigh criterion: angular or spatial resolution?
The Rayleigh criterion sets the fundamental limit for what features an optical system can resolve. Formally, the criterion is defined for some wavelength $\lambda$ in the case of a uniformly-...
0
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0answers
29 views
Parfocal length extender
How a parfocal extender works?
What are component parts of a parfocal extender? Is it a simple tube or other things such as lens are used in it?
2
votes
0answers
225 views
Infinity Corrected Microscope vs. $4f$ imaging system
This questions concerns three types of microscope systems and the differences between them. Let me lay out my understanding of these three types of systems. I am imagining imaging with a camera so ...
0
votes
0answers
28 views
Telecentric lens references, working distance formula
I would like to learn about telecentric lenses for use in an experiment. So far, I have found scant resources (mostly optical companies) and I understand the basic principal of a simple telecentric ...
0
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0answers
73 views
Question about transmission of paraboloidal light waves in bi-convex lens
The question is as follows:
Show that a paraboloidal wave centered at $z_1$ is converted by a lens of focal length $f$ into a paraboloidal wave centered about $z_2$, where $\frac1{z1} + \frac1{z2} ...
0
votes
0answers
14 views
Radiation that passes through aluminum foil for functional neuroimaging?
As a thought experiment, what kind of radiation could be used to perform functional neuroimaging in theory even if the person's head is covered in aluminum foil? To make things interesting, let's say ...
0
votes
0answers
24 views
Is light propagation being slowed down at the media interface?
Read the article and watch the video here: https://phys.org/news/2019-05-ultra-fast-imaging-technology-high.html.
If you click the video (especially the second one), it seems that the light was slowed ...
1
vote
0answers
24 views
How far will the imaging be? And is it possible to make it farther?
So currently I'm trying to make a smart glasses, where you have a projector that projects an image onto transparent flat glass, and some of the light will reflect into your eyes (something like the ...
2
votes
0answers
38 views
Can graphite be imaged through plaster?
There is a historical building near where I live where the walls are covered in pencil writing. The notes were taken over centuries by multiple generations of the family that lived there. There are ...
2
votes
1answer
39 views
Atomic Force Microscopy - Lateral vs. Depth Resolution
I'm trying to gain a better understanding of Atomic Force Microscopy, specifically the relationship between its lateral and depth resolution. I've seen a variety of metrics on the two, but in general,...
1
vote
1answer
120 views
Why was the imaging of M87 black hole easier than imaging the Milky way's Sagittarius A*? [duplicate]
In the recent EHT press release of the image of the super massive black hole at M87, I am curious to know why the super massive black hole at the centre of milky way has not been imaged yet.
10
votes
2answers
373 views
Orange ring in a black hole image
What exactly is the origin of the orange ring around M$87$?
I understand that the image was not taken in the visible light range. The colors are therefore artificial.
I also read that the image ...
0
votes
1answer
13 views
Ways to limit interaction volume in a SEM without changing e-beam energy (spot size)
All I can find online is that the interaction volume of a scanning electron microscope is affected by e-beam energy, angle of penetration, and sample composition. Are those really the only things that ...
0
votes
1answer
16 views
Error propagation in cone width for kinematic neutron imaging
I'm trying to figure out the error in the opening angle for a cone created with kinematic neutron imaging. The angle is defined as:
$$
\theta = \sin^{-1}\left(\sqrt{\frac{Ep}{E}}\right)\,.
$$
And I ...
2
votes
0answers
39 views
Can we image the interior of the earth by shooting weakly interacting particles through it?
Could we image the various layers of the earth by shooting weakly interacting particles through it? Let's say we shot a very high amount of neutrinos in one side (say, the north pole) and then ...
0
votes
0answers
33 views
Optics that translates object to image by a constant amount
For some application I was interested in an optics s.t. for any incoming ray the outcoming ray is parallel to the incoming ray and shifted by a distance $d$ (independent of the incoming ray) along the ...
0
votes
0answers
13 views
How to add protective enclosure around exposed thermal camera
First off, let me state that I'm not entirely sure this is the right forum for this question. This was the only section I found multiple questions pertaining to thermal imaging, however, so I thought ...
0
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0answers
149 views
contrast in confocal microscopy
I observed fixed cells from mice tissue, thanks to confocal microscopy monochromatic 488nm. (without fluorescence staining)
In some slices, cells appear in black, and in other slices in white (...
5
votes
2answers
288 views
What is the theory behind imaging a precision pinhole?
In my efforts to characterise a 0.67 NA microscope objective (working distance of about 15mm, effective focal length of 25mm), I have placed a 20 micron precision pinhole at the focal plane of the ...
1
vote
1answer
70 views
What aberration causes the common “cross pattern” in astronomy images? [duplicate]
I am trying to understand the origin of the plus/cross-sign aberrations commonly seen for point sources in astronomical images, even ones created with professional-grade, high-quality optics. The one ...
2
votes
1answer
102 views
How do these toroidal reflectors form an image in two dimensions?
A torus has a major and minor radius, which means a symmetric section of one will have different focal lengths in its focal plane, or astigmatism. If it's from the "outside" of the torus (where you'd ...
2
votes
2answers
92 views
How can I focus an optical device at infinity, inside a room with limited space?
I have a custom coupled camera/spectrograph imaging system that I need to focus at infinity for a microscope setup. I can't move the device outside, where I would be able to use some distant object to ...
1
vote
2answers
2k views
Image formed via a converging lens when the object is placed at focal point
In the case where the object is placed at focal point F of a converging lens, the rays of light (the one passing through O and the one sent parallel to the principal axis never meet) so I am assuming ...
1
vote
2answers
204 views
Image distortion caused by camera in cylindrical tube
So the inspiration of this issue actually comes from an engineering point of view. The jist of the project is that I need a water proof enclosure to fit a camera in alongside other electronic ...
0
votes
1answer
83 views
Phase Retrieval and Oversampling
In signal and image processing theory, it is known that taking the Fourier transform of a zero-padded image gives the oversampled Fourier transform of the image. And that oversampling is a necessary ...
1
vote
2answers
85 views
Imaging resolution with laser
The transverse optical resolution of a lens, as determined by its point spread function, can be approximated as $w$ ~ Ī»/(2$NA$), where $NA$ is the numerical aperture and Ī» is the wavelength of the ...
1
vote
1answer
4k views
How do CRA (Chief Ray Angle) and FOV (Field of View) affect one another?
I've been researching CMOS image sensors for a small working-distance, low-light application. From this, I roughly know I need a field of view of approximately 100-120 degrees. However, upon looking ...
0
votes
2answers
96 views
Spatial frequency and high contrast imaging
I am having a issue with a question with regards to how spatial frequency and high contrast are related.
Explain how high contrast resolution of an imaging system may be expressed in terms of a ...
1
vote
1answer
170 views
Rectilinear image projection in image stitching [closed]
For the pinhole camera model, the mapping from 3D to 2D coordinates is described by a perspective projection(rectilinear projection).
However for the image stitching application, perspective ...
2
votes
1answer
59 views
Which parts of the electromagnetic spectrum are difficult to image with? [closed]
Alternately stated question: What parts of the electromagnetic spectrum can't be used in traditional imaging techniques, and why not?
By 'traditional' I specifically mean using a lens (or some '...
1
vote
0answers
28 views
What is the difference between Synthetic Aperture Ultrasound and Ellipsoidal Backprojection?
What is the difference between Synthetic Aperture Ultrasound and Ellipsoidal Backprojection?
0
votes
1answer
316 views
Electron Microscopy: Are photons smaller than electrons?
So, I'm told that electron microscopy provides greater resolution than traditional photo/optical (i.e. visible light) microscopy, due to the (ahem) "fact" that "electrons are physically smaller than ...
0
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0answers
49 views
Calculating light level radiating back to camera from rough surface
Problem statement: I have an imaging sensor (ācameraā) that has a minimal response specified at 1000 lux. This camera is set up to resolve a rough surface at 1 meter distance. Alongside the camera is ...
1
vote
0answers
66 views
How does a microbolometer array resolve temperature?
I'm told that handheld thermal sensors measure black body radiation with a bolometer array.
I don't understand how ones goes from IR photon counts to temperature. Is the camera somehow spectrally ...
0
votes
1answer
59 views
Probe forming angle and resolution of a Scanning Electron Microscope
A SEM operates at $30keV$ and uses an objective lens with spherical aberration constant, $C_s=2mm$.
Calculate the optimal probe forming angle for this system.
Calculate the resolution of ...
