Questions tagged [imaging]

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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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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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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 ...
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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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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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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 ...
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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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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 ...
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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 ...
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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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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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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 ...
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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 ...
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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?