Questions tagged [infrared-radiation]

A region of the electromagnetic radiation spectrum where wavelengths range from about 700 nm to 1mm

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Is cooling by infrared absorbing rectenna possible?

We know that every hot objects emits IR radiation. We also know that plasmonic rectenna can absorb and convert IR radiation to electricity. Question: what will happen if we put an hot object inside a ...
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Momentum integral yielding $\delta$ function

I am reading the paper Asymptotic conditions and infrared divergences in quantum electrodynamics by P. P. Kulish & L. D. Faddeev (the paper is not important for the question I think, but I will ...
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Dielectric function of carbon dioxide gas in infra-red range

I did calculations on Rayleigh scattering by CO2 molecules in earth atmosphere, taking into account decreasing density with altitude and so on. The problem is that I can't find the datas on the carbon ...
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How does wavelength affect scattering?

Let's say that I have a detector and a few sources of light (think lightbulbs). The sources are all the same power and emit different colours of light. We're on the surface of Earth. As I walk further ...
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Why does cooling down thermal imaging cameras increase sensitivity?

A lot of high-sensitivity thermal cameras and sensors are (cryogenically) cooled down to low temperatures to achieve these high sensitivities. For example. the Stinger missile, and the James Webb ...
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Is there a formula for the distance an infrared sensor "senses"? [closed]

I'm making a Raspberry Pi-based infrared sensor for a school research project. Here's the link for the infrared sensor that is attached to the Raspberry Pi. At the moment, I don't have much ...
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In FTIR, why is the sample interferogram out of phase with the background interferogram?

I am reading "Fourier Transform Spectroscopy" by Griffiths and de Haseth. In section 2.4 Apodization they state: I do not understand the physics behind why the sample interferogram is out ...
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QED Soft Theorems and Momentum Conserving $\delta$ function

The sub-leading soft theorem (or Low theorem) states that the radiative Feynman amplitude is associated to the non-radiative Feynman amplitude in the following way $$\mathcal{M}_{\text{rad}}(\omega_k,\...
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Will the spacing between the mirror segments of the Webb space telescope degrade the sharpness of its images?

I've noticed that the existing spacing between the 18 mirror segments of the Webb space telescope are many times the operational infrared spectrum wavelengths (i.e. 0.6-28μm) of the telescope meaning ...
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Can I able to detect (by long exposure shot) infra red region when black body is heated to its necessary temperature

When we heat a body ,it emits radiation in full spectrum with maximum spectral density at a particular wavelength depending on its temperature. When I heat the body to particular temperature , ...
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How can the limited to infrared James Webb space telescope do spectroscopy of the exoplanets' atmosphere without seeing in the visible spectrum?

image source: https://www.youtube.com/watch?v=bI-JIAmiL7A JWST will look for the composition of exoplanets' atmosphere using the spectroscopy method. However as far as I know for elements of the ...
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In general which laser would cut clear glass more easily, a visible spectrum laser or an infrared laser?

Assuming the two lasers have identical characteristics and power output except their wavelength, which one would be more successful and easy in cutting clear glass? In case there is doubt that you can ...
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Planck radiation law of a dielectric layer

Suppose we have a rectangular slab of thickness $h$, width $a$ and length $b$. The upper surface of the slab is put at constant temperature $T$ while all the rest is at initial temperature $T_0$. ...
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Infrared Wavelength Measurement and Identification

I have a heat panel that I would like to use with animals, so would like to know what IR radiation (Ie.A, B or C) it is putting out. I have spoken to the manufacturer but they do not know. What is the ...
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How fast can molecular vibrations become under the application of IR radiation?

It is my understanding that IR radiation can be absorbed by molecules when the frequency of the photon matches the natural frequency of the bonds in the molecule which can cause the amplitude and ...
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What is the science behind Red light therapy? Infared and low spectrum EM waves sounds fancy to some but is it more than heat and a red light bulb

I have some scientific background and I own horses. So many therapies to alleviate pain in horses are available on the market that are not regulated by any scientific body. The benefit and the ...
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How can a digital camera capture and render IR (and UV) light?

It is known that you can see IR with digital camera. I have personally tested with camera of phone and webcam with a RC of A/C. It is seen as mostly white light with red tint. I haven't tested with ...
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Why are only infrared rays classified as "heat rays"?

I've often heard that Infrared rays are called "heat rays". However, I feel like this term is a misnomer. Don't all the wavelengths of electromagnetic radiation carry energy? Judging by how ...
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Why does the fringe contrast disappear for a divergent beam (FTIR using a Michelson Interferometer)?

I am reading "Fourier Transform Spectroscopy" by Griffiths and Haseth. In section 2.6 Effect of Beam Divergence, the authors state that: When the extreme ray is out of phase with the central ...
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How does conservation of energy fit in with an object absorbing visible light rays but emitting IR rays?

When an object absorbs visible light (such as from the sun) it gains a certain amount of energy. Most objects then emit back IR radiation (without emitting back any visible light) which has a lower ...
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Does a difference in temperature between an object and its surroundings cause a net radiation of IR rays between them?

I know that when an object has more thermal energy than its surroundings, it will transmit thermal energy to its surroundings by conduction until it reaches thermal equilibrium with its surroundings. ...
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On heat and transparency

If heat is just our physical perception of infrared radiation (IR), is there a material transparent to heat, as is glass with respect to visible light?
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Does luminous efficacy differ between direct and reflected sunlight?

With the total visible light flux being equal does reflected sunlight (by the sky, environment or shading/light redirecting surfaces) have a smaller total energy per luminous flux and therefore ...
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Is there a classical mechanism for gas heating by incident IR?

Consider a cold gas in an otherwise empty chamber. The gas is then illuminated with a narrowband MWIR coherent source. Let us ignore kinetic interactions with the chamber walls. Is there a classical ...
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How much of the suns radiation is infrared from compression heat, not fusion?

Preface: Im a college level dropout, please dont stomp on my ignorance too hard. As mass falls into a gravity well, it compresses and heats up. Even if fusion didnt exist/occur, in a body as large as ...
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What colors reflects the most infrared radiation?

About fifteen years ago I read in a book (Physics by James Walker 3rd edition) that dark brown color reflects IR better than any other color and consequently weather heat since our bodies get most ...
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Why does the light of this infrared laser become visible after reflection?

We use a 780 nm laser in our lab, and that makes it in the near infrared (IR) range. The majority of people can not see this wavelength of light. However, when the beam reflects off of an object (see ...
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Are window glasses transparent or opaque to infrared radiation? [duplicate]

I have been trying to understand this concept to identify on the best option to reduce temperature in my room. I have read few article which stated that glass is transparent to IR radiation. ie Beyond ...
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Is there no way to bypass greenhouse gasses by converting excess heat to longerwave radiation?

The problem with greenhouse gases, as I understand it, is that they absorb and emit radiation within the thermal infrared range leading to increased temperatures on Earth. According to some sources, ...
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Is there any website or method to calculate the refractive index of gases like $\rm CO_2$ in the mid IR?

I want to know the complex refractive index of some gases like CO2, CH4, C2H6 .. etc in the mid infrared. Is there any website, software or a method to know them?
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Effect of coloring on emissivity at temperatures below 150C?

I'm working on Aluminum/Copper heat sink design optimization and came across this thought. The heat source on which the heat sink is going to be placed is approx 100C. Forced convection is absent, so ...
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What happens at the interference of infrared and ultraviolet rays? [duplicate]

This question occurred to me, and I was wondering what everybody else thought about it. Lets say that an infrared laser and an ultraviolet laser were to intersect at a right angle. What kind of things ...
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Is IR light emitted, rather than reflected?

When I look at an object in the sunlight, I'm looking at photons reflected back from the object. But if I wear infrared goggles and look at an object in the dark, am I looking at photons that are ...
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Cardboard and IR transmittance

Does infrared radiation transmit (not absorb & re-radiate) through cardboard in the IR-B or IR-C bands? I know IR-A does not transmit well but am curious about the longer wavelengths and can't ...
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Heat lamp: What material will block visible light but let IR pass?

Everything I search for, no matter where or how I phrase the question, invariably results in answers for how to block IR light. That's not what I want to do. I have a parabolic heat lamp that emits a ...
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If all objects emit IR radiation, would it be sufficient to place an IR mirror behind an object to propel it forward?

I'm assuming objects don't move all the time because they emit IR radiation in all directions. If we have an IR mirror behind the object to focus their direction, would this propel the object forward?
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Hydrogen-One (HI) Image and R-band

In the paper below, on page 3, it says "In the lack of HI image, we use the r-band b/a ratio to correct for the inclination". Am I correct in thinking that what this means is that if we ...
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Physics of an infrared thermometer

The thing about infrared thermometers that bugs me is how can you get the same temperature reading regardless of the distance to the object. Shouldn't there be a difference when measuring from two ...
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How can I cluster infrared spectra?

This is sorta a cross-post from my post in StackOverflow. Although, rather than seeking help with the code I'm here asking for help with a physical/mathematical/statistical problem associated with the ...
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Questions about sources of Infrared Radiation

Very simple question but I came across a website discussing sources of infrared radiation and it used an example to illustrate which objects emit more infrared than others. It said 'a candle flame ...
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What variables affect an object's absorption of invisible light?

Say I have two objects (we'll call them object $1$ and object $2$) of the same material but of a different colour, placed at the same distance away from another object (we'll call object $3$) that ...
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Specular Reflection of IR Light

I have started to use thermal imaging cameras more and more and realized that I can see the reflection of my self bouncing off of a glass window through the IR camera. When viewing it on my monitor, I ...
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Why can some electromagnetic waves heat things up while others cannot?

I have read that heat radiation happens in the form of infrared, which is an EM radiation with a longer wavelength than visible light. So the heat radiation that you can feel in an oven or under the ...
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What effect does surface have on light absorption at different wavelengths?

I am a bit confused and need a well rounded explanation. Have a look at two scenarios: A metal plate with small scratches on it appears diffuse in the optical spectrum, because the roughness reflects ...
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Infrared light out of sunlight

I want to filter out any light of higher frequencies and pass only infrared. How is it done?
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Understanding atmospheric transmission's effect on IR camera [closed]

I'm using an IR camera to view a person at 1 meter, and then 5 meters. When I view them at 5 meters the max temperature I see for them drops by about 1 degree Fahrenheit. I assume this is because the ...
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Why does the earth and oceans emit primarily infrared photons?

Climate on earth depends a lot on infrared photons being emitted by the earth and its oceans. I want to know why the atoms in earth elements emit infrared photons after absorbing visible light, UV ...
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What would cause an infrared thermometer to malfunction in a specific room?

The situation is as follow: When used to measure body temperature, my infrared thermometer will always measure an abnormal high temperature in ONE certain room (40/41 degree celcius), but it will ...
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Can a slab with a set of IR torches on it help to prevent blossom freeze in early spring?

Every year there are lot's of problems with blossom freeze caused by sudden drop in temperature of the envirement and cold winds. Can a set of parallel infrared torches have a low drop of intensity ...
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Infrared divergences: total energy of soft photons

One way to deal with IR-divergences in QED is sum over soft photons, which can't be detected due to finite sensitivity of detector: only photons with energy bigger that resolution of detector $E>E_{...
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