Questions tagged [imaging]
The imaging tag has no usage guidance.
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questions
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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-...
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20 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?
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42 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 ...
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21 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 ...
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23 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} ...
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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 ...
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23 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 ...
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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 ...
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0answers
34 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 ...
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1answer
35 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,...
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1answer
93 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.
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1answer
245 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 ...
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1answer
7 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 ...
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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
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0answers
37 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 ...
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0answers
31 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 ...
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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 ...
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138 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 (...
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2answers
204 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 ...
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1answer
57 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
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1answer
69 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 ...
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0answers
11 views
What is the theoretical resolution limit of magnetometers / magnetoencephelography?
I recently read this article about a group of physicists and neurobiologists working on developing advancements to magnetoencephelography, presumably based on new quantum metrology and quantum ...
2
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2answers
63 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 ...
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2answers
1k 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 ...
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2answers
123 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 ...
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1answer
58 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 ...
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2answers
69 views
Imaging resolution with laser
The transverse optical resolution of a lens, as determined by its point spread function, can be approximated as $w$ ~ λ/(2$NA$), where $NA$ is the numerical aperture and λ is the wavelength of the ...
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1answer
2k 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 ...
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2answers
75 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 ...
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1answer
125 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
57 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 '...
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0answers
27 views
What is the difference between Synthetic Aperture Ultrasound and Ellipsoidal Backprojection?
What is the difference between Synthetic Aperture Ultrasound and Ellipsoidal Backprojection?
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1answer
107 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 ...
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48 views
Calculating light level radiating back to camera from rough surface
Problem statement: I have an imaging sensor (“camera”) 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 ...
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43 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 ...
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1answer
47 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 ...
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0answers
32 views
Defraction limits of muli-image super resolution for satellites
Is it possible to increase the resolution of satellite imagery with multiple passes through the use if multi-image super resolution algorithms?
I would imagine that probably the optical systems are ...
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1answer
29 views
STtimulated Emission Depletion (STED) microscopy theory
I am recently reading STED microscopy. In the Wiki, STED is described to be a process that the atoms of the flurophore in the periphery of the focal point is stimulated to emit light of wavelength ...
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1answer
157 views
What is ptychography, in a nutshell?
I've heard of ptychography as an imaging technique a number of times in the past, and recently I found myself in need of a refresher on what it actually entails. Unfortunately, the Wikipedia page on ...
2
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1answer
169 views
Point spread function (PSF) measurement theory
Point spread function (PSF) describes the volumetric image of a point light source in the object space. But in practice, we measure the PSF by moving the light source (the fluorescence bead) and ...
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2answers
87 views
Out of all the medical imaging radionuclides, why is technetium-99m the most common?
There are medical tracers like Xe-133, I-131 etc.(what are some other ones?), but why is Tc-99m the most common (most suitable)?
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57 views
Is it possible to make an imaging array differential?
As described in this comment on a Slashdot post, exposing an imaging sensor to light accumulates charge in a well (i.e. pixel) on a piece of silicon. The well can only hold so much charge (release so ...
2
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1answer
172 views
When does a lens go from 'linear' to 'fisheye'
I recently ordered some lenses in an attempt to gather more light from an object being imaged in very low light conditions. I'm trying to use a converging lens with the object > 2f from the lens so it ...
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1answer
54 views
Make a projected image smaller?
A friend has a Batman nightlight that projects Batman onto her ceiling. She has vision problems because of a head injury. She could see Batman fine when she was in an upstairs bedroom and the ceiling ...
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1answer
208 views
2D elliptic gaussian beam on tilted wall
I can calculate laser's beam cross section at every point along z-axis. But how to do a "projection" of this beam on tilted wall? I see option to use ray tracing, but there is possibly a better way.
...
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5answers
2k views
Technical explanation of “Hitachi lensless camera”
Hitachi is bragging about a thin lensless camera. I can't find any technical information on how it works---just press releases etc.† Can anyone work backwards from the published descriptions to ...
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3answers
7k views
How do I read a scanning electron microscopy (SEM) image?
I'm trying to figure out the magnification of this image. Can anyone explain how to read the numbers at the bottom? What do they mean and how can I determine the magnification from them?
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1answer
258 views
What do certain pixels in the Fourier transform of a 2D image represent?
I understand the 1D Fourier transform but I don't have any experience with the 2D version so there are a couple of things I'm wondering about. If you take the Fourier transform of a 2D image you end ...
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510 views
How to read Inverse Pole Figures (IPF) images
When (Electron BackScatter Diffraction) EBSD maps are procesed the output crystallographic orientation is derived into Euler map and three Inverse pole figures (IPF) maps.
In the example there is IPF-...
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1answer
291 views
biconvex vs plano convex lenses for 4f imaging [closed]
Will biconvex or plano convex lenses be best for a 4f optical imaging system with 10x magnification and why?
