Multilayer thin-film coatings have a large number of interfaces, since they are generally comprised of alternating layers of a high- and low-index layer materials. The fraction of incident light intensity Iin that is reflected (IR) and transmitted (IT) through a thin-film coating can be calculated from the indexes of refraction and the precise thicknesses of each layer. These intensity reflection and transmission functions R(l) and T(l), respectively, generally depend strongly on the wavelength of the light, because the total amount of light reflected from and transmitted through the coating comes from the interference of many individual waves that arise from the partial reflection and transmission at each interface. That is why optical filters based on thin-film coatings are called “interference filters.”

You can assign different ring lights to different channels via either the remote or the on-body controls, and then change the settings of one light without changing the rest.

For testing, we mounted each ring light to our desk and used it as a primary source of light for video calls and as a desk light over the course of a few days. We took notes on how easy each light was to install, power on and off, and adjust. We also noted how intense each light felt after sitting in front of it for over 30 minutes.

Polarization is a fundamental property of light. While many optical applications are based on systems that are “blind” to polarization, a very large number are not. Some applications rely directly on polarization as a key measurement variable, such as those based on how much an object depolarizes or rotates a polarized probe beam. For other applications, variations due to polarization are a source of noise, and thus throughout the system light must maintain a fixed state of polarization – or remain completely depolarized – to eliminate these variations. And for applications based on interference of non-parallel light beams, polarization greatly impacts contrast. As a result, for a large number of applications control of polarization is just as critical as control of ray propagation, diffraction, or the spectrum of the light. Yet despite its importance, polarization is often considered a more esoteric property of light that is not so well understood. In this article our aim is to answer some basic questions about the polarization of light, including: what polarization is and how it is described, how it is controlled by optical components, and when it matters in optical systems.

It is also possible to take advantage of an appreciable difference in reflected or transmitted phase for p- and s-polarized light over a region of the spectrum where the reflected and transmitted intensities are essentially equal, thus forming a waveplate.

Most polarizing beamsplitters are very efficient polarizers for the transmitted light (i.e., the ratio of desired to undesired polarization is very high); however, the reflected light generally contains some of both polarization components.How does a polarizer work? There are different ways of making a polarizer, and they are not described in detail here (see [1] for more examples). However, as an example consider one of the most popular absorbing polarizers: the well-known Polaroid “H-Sheet.” This polarizer, invented by E. H. Land in 1938, is a plastic, Poly-Vinyl Alcohol (PVA) sheet that has been heated and then stretched in one direction, forming long, nearly parallel hydrocarbon molecule chains. After dipping the sheet into an iodine-rich ink, long iodine chains form along the hydrocarbon molecules. Electrons freely move along the iodine chains, but do not easily move perpendicular to the chains. This ability for electrons to move freely in one direction but not the perpendicular direction is the key principle upon which most absorbing polarizers are based.

In general, ring lights with front diffusion panels that were too transparent—allowing the LED bulbs to be clearly visible—were uncomfortable to sit in front of for extended periods. On camera, these lights produced harsher highlights and rougher transitions to darker areas.

The Lume Cube Cordless Ring Light can work without cables, like our upgrade pick, but it uses large batteries that need to be plugged into the back of the light. In our tests, the batteries were difficult to fully plug in and remove. Most of our test panelists failed to install the batteries properly. The front diffusion panel on the cordless Lume Cube is less opaque than our picks, and most of our testers said the light from it was uncomfortable.

Because of this relationship, a material with birefringence Dn of the appropriate thickness L to convert linear polarization to circular polarization is called a quarter-wave plate.What causes materials to be birefringent? Some materials, especially crystals, are naturally anisotropic at microscopic (sub-wavelength) size scales. For example, Calcite (CaCO3) is shown in the drawing below. The structure, and hence the response to polarized light, along the c direction is markedly different than that along the a and b directions, thus leading to a different index of refraction for light polarized along this direction.

We can see that the tip of E traces out a circle as we follow the wave along the z axis at a fixed time. Similarly, if we sit at a fixed position, the tip of E appears to trace out a circle as time evolves. Hence this type of polarization is called circular polarization.

The quality of its light is nearly as pleasing as that of the Elgato Ring Light, but it doesn’t include any apps or a remote, so you need to adjust the settings using toggles on the back of the light. It doesn’t get as dim at its lowest brightness setting as our picks, either. And it’s more expensive than our top pick, so we really only recommend it if you want the simplest possible device with the highest quality light.

The amplitude E, or the potential for a charged particle to feel a force, is vibrating along both the x and y directions. An actual charged particle would feel both of these fields simultaneously, or it would feel

This smaller, lightweight ring light has a soft glow that’s easy on the eyes. Just don’t expect extras like a remote, apps, or being able to make granular adjustments. It’s ideal for casual video calls.

If you only plan to use a ring light once in a while, the Godox LR120 Ring Light is an extremely simple yet effective option. It’s smaller than our other picks, so the light is less diffused and has to be positioned closer to the subject you want to illuminate, but the front diffusion panel is opaque enough to hide the LED bulbs.

Some polarizers eliminate the non-passed polarization component (Ey in the above example) by absorbing it, while others reflect this component. Absorbing polarizers are convenient when it is desirable to completely eliminate one polarization component from the system. A disadvantage  of absorbing polarizers is that they are not very durable and may be damaged by high intensity light (as found in many laser applications).When a reflective polarizer is operated in such a way that the blocked (i.e., reflected) polarization component is deflected into a convenient direction, such as 90° relative to the transmitted polarization component, then the polarizer acts like a polarizing beamsplitter, as shown below.

Discover the light sources that will best suit your spectroscopy needs. We have a variety of light sources for UV, Visible, NIR, and Raman spectrometers.

The amount of light output in each polarization state can be determined by simply breaking up the incident light into its two polarization components (s and p), and then calculating how much of each intensity is transmitted and reflected. For systems based on incoherent light, this level of detail is usually sufficient to keep track of the impacts of components like optical filters on polarization.For some optical systems – particularly those based on coherent light and that utilize or are sensitive to interference effects, for example – the complete state of polarization should be tracked at every point through the system. In that case, it is important to understand that optical filters based on multilayer thin-film coatings not only reflect and transmit different amounts of intensity for the s and p polarization states, but also impart different phases to the two different states. And both the amplitude and phase contributions can depend strongly on the wavelength of light. Thus, in general, an optical filter can act like the combination of a partial polarizer and a birefringent waveplate, for both reflected and transmitted light.To determine the effect of an optical filter on the light in such a system, the incident light should first be broken up into the two fundamental components associated with the plane of incidence of the filter (s and p components). Then, the amplitude and phase responses of the filter for the s and p components should be applied separately to each of the incident light components to determine the amplitudes and phases of the reflected and transmitted light components. Finally, the reflected s and p components can be recombined to determine the total reflected light and its state of polarization, and likewise for the transmitted light. These steps are illustrated in the diagram below.

Unpolarized light can be polarized using a “polarizer” or “polarizing beamsplitter,” and the state of already polarized light can be altered using a polarizer and/or optical components that are “birefringent.” In this section we explore some examples of these types of components.

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When an optical filter is used at a non-normal angle of incidence, as is common with so-called “plate beamsplitters,” the filter can impact the polarization of the light. If the incident light is incoherent and unpolarized, and the optical system is “blind” to polarization, the standard intensity reflection and transmission functions R(l) and T(l) may be determined for the new angle of incidence, and they are sufficient to characterize the two emerging beams.

H Moosmüller · 2009 · 931 — Light absorption by aerosols contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer.

This light gives off beautifully diffused light and comes with high-quality accessories. It works with both a mobile app and desktop software, so you can adjust the light easily.

This light gives off beautifully diffused light and comes with high-quality accessories. It works with both a mobile app and desktop software, so you can adjust the light easily.

A well-designed ring light provides soft, even illumination that enhances your presence and ensures you’re always seen in the best light.

You can change its brightness and color temperature in 1% increments via Elgato’s mobile app (Android, iOS) or its desktop software Control Center. That means you can make precise adjustments without having to move from your location.

Good lighting is the key to looking sharp and professional on camera, whether you’re streaming, vlogging, or sitting through endless video calls. Without it, even high-quality cameras can make you appear dull and out of focus.

Notice from the graph above on the right that for the case of reflection from a higher-index region to a lower-index region (in this case glass-to-air, or ni = 1.5 and nt = 1.0), the reflectivity becomes 100% for all angles greater than the “critical angle” θc = arcsin(nt/ni) and for both polarizations. This phenomenon is known as “Total Internal Reflection” (TIR).For angles of incidence below the critical angle only the amplitudes of the different polarization components are affected by reflection or transmission at an interface. Except for discrete changes of p (or 180°), the phase of the light is unchanged. Thus, the state of polarization can change in only limited ways. For example, linearly polarized light remains linearly polarized, although its orientation (angle ) may rotate. However, for angles greater than θc, different polarizations experience different phase changes, and thus TIR can affect the state of polarization of a light wave in the same way birefringence does. Thus linearly polarized light may become elliptical, or vice versa, in addition to changes in the orientation.

Some materials have a different index of refraction for light polarized along different directions. This phenomenon is called birefringence. For example, suppose light polarized along the x direction sees an index of nx, while light polarized along the y direction sees an index ny. Now suppose linearly polarized light passes through a piece of such a material of length L, where the linear polarization axis is oriented at 45° with respect to the x and y axes. The fixed time picture thus looks like:

We also tested all of our contenders with a panel of paid testers, including individuals with dexterity and vision impairments, as well as a wide range of ages and body types. We noted any challenges they faced controlling the lights, and how they felt about the quality of the light.

If Ax  Ay , the total wave E is linearly polarized, but it is no longer oriented at 45° with respect to the x axis. In fact we can see that it is oriented at an angle  where

We can see that in general the light emerges in a different state of elliptic polarization. In fact, for the example illustrated above, the particular choice of L for a given difference between nx and ny causes the linearly polarized light at the input end to be converted to circularly polarized light at the other end of the birefringent material. How did this happen? Let’s look at the math. Consider the phases accumulated by the two component waves as they travel through the birefringent material. The waves can be described by

Coherent sources of light are those sources which emit a light wave having the same frequency, wavelength and in the same phase, or they have a constant phase ...

During testing, a few of the panelists said they appreciated the stepped settings because the feature made it easy to replicate brightness levels in the future—for example, “two clicks of brightness.”

Wirecutter is the product recommendation service from The New York Times. Our journalists combine independent research with (occasionally) over-the-top testing so you can make quick and confident buying decisions. Whether it’s finding great products or discovering helpful advice, we’ll help you get it right (the first time).

This powerful yet compact technology can reorient light from the source to any direction in three-dimensional space and take uneven, omnidirectional LED output.

Wirecutter’s head of photography Michael Hession and photo editor Rozette Rago helped us determine the most important features to look for in a ring light:

Linear polarization

Whether you work from home or you need to nail a job interview via Skype, these are Wirecutter’s tips for looking and sounding like a pro on video calls.

What if the two components Ex and Ey have unequal amplitude factors? We can see that the light wave is still linearly polarized.

It’s not as customizable as our other picks. Unlike the Elgato and Lume Cube ring lights we recommend, which allow for precise 1% brightness adjustments and 50 or 100 Kelvin color-temperature changes, respectively, the LR120 changes brightness and color temperature in broader 10% steps, making it less customizable overall. Most people won’t find this too limiting, but those who want to dial in exact color temperature or brightness will probably want to opt for our top or upgrade pick.

You can control the light in a variety of ways. Besides the physical buttons on the light itself, the Elgato light can also be controlled remotely with the Elgato Control Center app for mobile (Android, iOS) or its desktop Control Center software (available for Mac and Windows). Both are simple to use, with nothing more than a power button and sliders to adjust the color and brightness.

Ring lights are suitable for many different image processing tasks. They are most commonly used as a bright field configuration in the ...

Linearlypolarized light

All of the states of polarization described above are actually special cases of the most general state of polarization, called elliptical polarization, in which the tip of the electric field vector E traces out an ellipse in the x-y plane. The two components might have unequal amplitudes Ax  Ay , and also might contain a different relative phase, often denoted  That is, we may write generally

This smaller, lightweight ring light has a soft glow that’s easy on the eyes. Just don’t expect extras like a remote, apps, or being able to make granular adjustments. It’s ideal for casual video calls.

This is especially useful if you’re using the Ring Light Pro for filming a project and need to make sure the lighting is consistent, or if you routinely use the light in a couple of different environments. It makes it easy to save the settings for each environment and then easily switch between them.

Because the polarization response of a tilted multilayer thin-film coating can be very strong, optical filters can make excellent polarizers. For example, a basic edge filter at a high angle of incidence exhibits “edge splitting” – the edge wavelength for light at normal incidence shifts to a different wavelength for p-polarized light than it does for s-polarized light. As a result, there is a range of wavelengths for which p-polarized light is highly transmitted while s-polarized light ishighly reflected, as shown below.

Polarization is a critical property of light for many optical systems and applications. This brief tutorial summarizes some of the most basic aspects of polarization, including how it is described, the impact of polarizing and birefringent elements on light, and how optical interfaces and filters can change the polarization of light.

The remote turns off after a minute of inactivity, so you first need to turn on the remote (by pressing the power button) before turning on the ring light. Since most remotes are always-on, it took us some time to adjust to pressing the power button without seeing the light turn on immediately.

If the difference between the two phase values is p/2, then the wave emerging from the material (say into air) will be circularly polarized. This occurs when

Brightness and color are adjustable in 1% increments, and the Ring Light Pro comes with a remote so you don’t have to get behind the camera to change your settings. With the remote, you can save up to three presets to switch between scenes or lighting conditions easily. The light is 17.5 inches in diameter, slightly larger than our top pick, but similar in overall light distribution.

This smaller, lightweight ring light has a soft glow that’s easy on the eyes. Just don’t expect extras like a remote, apps, or being able to make granular adjustments. It’s ideal for casual video calls.

The Elgato Ring Light is an excellent choice for anyone who needs a reliable, high-quality lighting solution. While most ring lights we tested in this price range give off harsh light with unflattering highlights, the Elgato light delivers softly diffused light that’s flattering in nearly all setups.

Nearly all of our testers found its glow comfortable enough for extended use—something that can’t be said for other cheap ring lights we tested.

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This ring light can charge your phone. Two 5-volt USB-A ports are on the back of the light’s control unit to charge your phone or other small electronic devices.

However, if the optical system is in any way sensitive to polarization, even when the incident light is unpolarized, it is important to recognize that the beamsplitter can transmit and reflect different amounts of the “s” and “p” polarization states, as shown below.

This light gives off beautifully diffused light and comes with high-quality accessories. It works with both a mobile app and desktop software, so you can adjust the light easily.

The Godox LR120 Ring Light is a compact, lightweight option that delivers a soft, flattering glow. At 12 inches in diameter, it’s smaller than our other picks, making it easy to move and store. The smaller size also means you can’t position yourself as far from this light as you can from our other picks, because it provides more narrow, concentrated coverage.

This ring light has a built-in battery that can run up to 70 minutes at full brightness. It can also charge your phone while you record.

The included accessories are high quality. The Elgato light is primarily aimed at people who plan to use the light at a desk, so the box includes a sturdy C-clamp and a telescopic arm. Compared with most of the other models we tested, whose included accessories feel more like a flimsy afterthought, the Elgato light’s hardware feels durable and well constructed.

The Neewer 18-inch LED Ring Light (RL-18) was more of a hassle to use than our picks. It has brightness knobs but no in-line controls or remote control. It comes with two plastic filters you have to attach to change the color temperature to 3,200 K or 5,600 K, and the red filter colors everything in a hideous orange light. This ring light also made everything look overexposed at all but the lowest brightness temperatures.

You can change the settings remotely. The Ring Light Pro comes with a remote that lets you power the unit on and off, change the brightness and color, and switch between channels.

The remote is built into the cable. The LR120’s controls are built into its power cable rather than an app or separate remote. A simple in-line remote, located midway along the cord, offers buttons to turn the light on and off, adjust brightness, and switch between color temperatures.

Its light is as excellent as our top pick’s. The Ring Light Pro uses the same rim-mounted LEDs as the Elgato Ring Light, so the light it produces is just as beautifully diffused. Compared with some of the cheaper ring lights we tested, it’s a huge step up in comfort and appearance.

Additionally, unlike our other picks (which use rim-mounted LEDs for softer illumination), the LR120’s LEDs face directly forward. While this light’s opaque diffusion panel does a good job of softening the light, preventing the bulbs from being harsh or distracting, the light is still more directional and concentrated than what you’d get from our rim-lit picks.

Its light isn’t as diffused as that of our other picks. The smaller 12-inch diameter of this light means it doesn’t provide the same coverage as our larger 17-inch picks. That won’t be a problem if you plan to use the ring light positioned 2 to 3 feet away from whatever you’re lighting. Any more than that, however, and you may find the light will start to become harsh or dim.

I’m an associate staff writer at Wirecutter covering work-from-home equipment. In addition to this guide, I’ve authored several guides about home-office and hobby gear, including webcams, vlogging gear, and craft cutters.

The Elgato Ring Light provides bright, even illumination for your setup, whether you’re applying makeup, taking a Zoom call, painting miniatures, or tattooing someone. The light it cast was the most pleasant of all the lights we tested, and it was also a favorite among our paid testers. It comes with a range of useful accessories, and it’s paired with mobile and desktop apps that can help you adjust settings on the fly.

Just remember to turn the switch back on before using the remote—otherwise, the remote won’t be able to power the light on.

Light from the Lume Cube Ring Light Pro is as diffused and lovely as that of our top pick, but it offers a few quality-of-life improvements—albeit at a significant jump in price. Specifically, we love that it can be used wirelessly, can charge your phone, and remembers your favorite settings (with the included remote).

This ring light has a built-in battery that can run up to 70 minutes at full brightness. It can also charge your phone while you record.

The more visible the bulbs, the worse the shadows. In some cases, when the LEDs were fully exposed, subjects cast multiple shadows—the opposite of what you’d expect from a properly diffused light source. Nearly all paid testers with vision sensitivities found these lights difficult to look at, and some even described them as painful.

Several of our testers who frequently do self-tape auditions praised this feature, saying it would make it easier to film in better locations in their apartments without being tethered to a wall for power.

and where, as before, E = Ex< + Ey. The three special cases described in sections a, b, and c above thus correspond to: (a) Ax = Ay and  = 0 (linear polarization; equal amplitudes); (b) 

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It’s easy to get up and running with Zoom, but you may not know about some of its best, most useful videoconferencing features.

Infrared Light Sources are used for in-vehicle sensing light sources such as those for driver monitoring systems and gesture control, as well as for security ...

A ring light is a simple, cost-effective option that anyone can set up and use. It makes the most sense when you need just a bit more emphasis on yourself in a space without a lot of natural light and you don’t have the space to invest in a bulkier softbox lighting setup.

Using this description of a single transverse orientation of a light wave, we can now consider multiple orientations to describe different states of polarization.

Circularlypolarized light

The Neewer 12-inch Ring Light (RH12B) was one of the least comfortable models in our tests. Nearly all of our panelists said it was too harsh on the eyes and mentioned that they found it difficult to look at for more than a few moments. It includes “effect” lighting modes that simulate fire or strobe lights, but none of our testers could see a practical use for them.

It can work wirelessly. Unlike our top pick, which needs to be connected to power to function, the Ring Light Pro has a built-in battery that can run up to 70 minutes at full charge.

The LED lights in the GVM Ring Light 14-inch and 18-inch face the subject, and the diffusion panel isn’t as opaque, so the quality of light is not as pleasant, with stronger unflattering highlights. The included accessories are made of cheap plastic and don’t seem like they’ll last. Plus, the 12-inch light would sometimes power off when we raised the brightness to max.

This ring light has a built-in battery that can run up to 70 minutes at full brightness. It can also charge your phone while you record.

To understand the polarization of light, we must first recognize that light can be described as a classical wave. The most basic parameters that describe any wave are the amplitude and the wavelength. For example, the amplitude of a wave represents the longitudinal displacement of air molecules for a sound wave traveling through the air, or the transverse displacement of a string or water molecules for a wave on a guitar string or on the surface of a pond, respectively. We will refer to the amplitude of a light wave with the letter “E.” The amplitude of a light wave represents the potential for a charged particle (such as an electron) to feel a force – formally it may represent the “electric field” of an electromagnetic wave. Because this potential vibrates along the directions transverse to the direction the wave is traveling, light is a “transverse wave,” just like the waves on a string or water surface.Because light is a transverse wave, and because there are two transverse dimensions, there are fundamentally two distinct directions in which the light wave may oscillate. Let’s call these the x and y directions for a light wave traveling along the z direction. We’ll call the two distinct waves Ex and Ey, where we denote these by vectors to remind us that they point in (or oscillate along) a certain direction (the x and y directions, respectively).The amplitude of the light wave describes how the wave propagates in position and time. Mathematically, we can write it as a “sine wave” where the angle of the sine function is a linear combination of both position and time terms:

A ring light is exactly what its name suggests: a doughnut-shaped light typically made of rows of LEDs. The halo shape diffuses light over a wide area, reducing shadows and washing away blemishes for a more flattering appearance. The space in the middle of the light is a great place to mount a camera or phone, because you get an even distribution of light around the lens.

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When the electric field of a light wave encounters the sheet, the component parallel to the chains causes electrons to oscillate along the direction of that component (Ey in the above example), thus absorbing energy and inhibiting the component from passing through the sheet. Because electrons can not respond to the other component (Ex), it is readily transmitted.

At 17 inches in diameter, the Elgato’s light wraps further around the subject for better diffusion. It’s also large enough to allow for more distance between the unit and subject while still being properly exposed.

The front panel is also made of glass instead of plastic, with an internal grid structure that further breaks up the beams of light created by the LEDs. The result is a soft, even glow around the ring that’s easy on the eyes, with gentle highlights and smooth transitions into shadowed areas.

Though it lacks advanced features, such as wireless operation or fine-tuned adjustments, its gentle, even light makes it a great choice for casual video calls or simple setups.

where A is called the “amplitude factor,” the variable l (“lambda”) is the “wavelength” (units of nm), and the variable v (“nu”) is the “frequency” (units of Hz, or sec–1). If a snapshot of the wave could be taken at a fixed time, l would be the distance from one wave peak to the next. If one sits at a fixed point in space and counts the wave peaks as they pass by, v gives the frequency of these counts, or 1/v gives the time between peaks. The sign between the position and time terms determines the direction the wave travels: when the two terms have the opposite sign (i.e., the “–” sign is chosen), the wave travels in the positive z direction. For convenience we often use two new variables called the “wavenumber” k = 2p/l and the “angular frequency” 2pv (“omega”), which absorb the factor of 2p, so that the wave amplitude can now be written more compactly as

The Yesker 14-inch LED Ring Light was our previous recommendation, but in the latest round of testing we found that its light was harsher than that of its rim-mounted counterparts. The Yesker light’s diffusion panel is semi-transparent, and several of the paid testers said that being able to see the wavy pattern of the LED bulbs was distracting and made the light hard to look at.

Its light is effectively diffused. As opposed to most ring lights, where the LEDs are mounted to the back panel and directly face the subject, the Elgato Ring Light’s LEDs are positioned along the inner perimeter of the ring and face inward. That means the light coming through the front panel is softer than what we saw from cheaper ring lights we tested.

After a new round of testing, we’ve made the Elgato Ring Light our top pick, the Lume Cube Ring Light Pro our upgrade pick, and the Godox LR120 our new budget pick.

The Lume Cube Ring Light Pro produces lovely light, but where it really shines is with its built-in battery. It can wirelessly illuminate a scene for over an hour at full brightness, and it has two USB outlets to charge your phone or other small devices. With no need to hunt for an outlet or deal with tangly charging cables, the wireless Ring Light Pro is especially helpful to anyone who plans to use the ring light on location or needs to film self-tape auditions often.

If you want a ring light that’s similar to our top pick but prefer not to use an app: Consider the LumeCube Ring Light Mini. It’s 12 inches wide—5 inches smaller than our top pick—but comes with high-quality, sturdy accessories, including a C-clamp and tripod feet for tabletop use.

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A polarizer transmits only a single orientation of linear polarization, and blocks the rest of the light. For example, a polarizer oriented along x passes x and blocks Ey.

Other materials are nominally isotropic, but when they are bent or deformed in some way, they become anisotropic and therefore exhibit birefringence. This effect is widely used to study the mechanical properties of materials with optics.

When light is incident on an interface between two different media with different indexes of refraction, some of the light is reflected and some is transmitted. When the angle of incidence is not normal, different polarizations are reflected (and transmitted) by different amounts. This dependence was first properly described by Fresnel, and hence it is often called “Fresnel Reflection.” It is simplest to describe the polarization of the incident, reflected, and transmitted (refracted) light in terms of a vector component perpendicular to the plane of incidence, called the “s” component, and a component parallel to the plane of incidence, called the “p” component. The “plane of incidence” is the plane which contains the incident ray and the transmitted and reflected rays (i.e., all of these rays lie on one plane). In the example in the diagram below, the plane of incidence is the plane containing the x and z axes. That is, Es || y, while Ep lies in the x-z plane.

You can use more than one together. If you want to use multiple Ring Light Pros—for example, during a photoshoot or for video production—you can do so thanks to the built-in channel system.

It can save your favorite settings. The included remote has a program button that saves your current settings. It can store up to three setting configurations.

A professional video producer shows how you can tweak the lighting you have in your home office to elevate your video-call look.

An earlier version of this article was written by Melanie Pinola, a Wirecutter senior staff writer who died in October 2024.

Lighting plays an important role in the image quality of your videos and photos, second only to the quality of your camera. But you don’t have to invest in a complicated lighting rig to get better close-ups.

But these features are really only worth the added cost if you plan to use this ring light for professional purposes, like on photo or video production, or for frequent self-tape auditions.

Investing in a handful of tools can improve the quality of your videoconferences, for both you and the other participants.

The angle of the reflected ray,θr, is always equal to the angle of the incident ray, θi, this result is called the “law of reflection.” The angle of the transmitted (or refracted) ray, θT, is related to the angle of incidence by the well-known “Snell’s Law” relationship: ni sin θinbsp;= nt sin θT. It turns out that s-polarized light is always more highly reflected than p-polarized light. In fact, at a special angle called “Brewster’s Angle,” denoted θB, the p-polarized component sees no reflection, or is completely transmitted. Brewster’s angle is given by θB = arctan(nt/ni). The power or intensity reflection coefficients for a light wave (i.e., the squares of the amplitude reflection coefficients) for air-to-glass (left) and glass-to-air (right) look like:

Suppose the two components have equal amplitudes again, but now consider the case where these two components are not in phase, such that the angles of the sine functions are different. In particular, suppose there is a constant phase difference of p/2 between them, which corresponds to a distance of l/4 in the “fixed time” picture. The x component is

Polarization

This light doesn’t have an app or a separate remote like our other picks, but you can still adjust and change its settings without getting up thanks to a controller built into the power cable. And though its light quality—in terms of color temperature and brightness—is not as customizable as our picks, it is significantly more affordable.

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The LED panel on the back is really bright. If you turn the Ring Light Pro off via the remote, the screen on the back remains illuminated, which could be annoying if you keep it in your bedroom. Fortunately, this can be easily fixed by toggling the switch on the back to power down the unit.

Unpolarizedlight

In other words, if we look down the propagation axis in the positive x direction, the vector E at various locations (and at t = 0) now looks like:

After researching and testing more than a dozen ring lights, we recommend the Elgato Ring Light as the best option for nearly any setup because of its beautifully diffused light, easily adjustable settings, and premium accessories.

In our tests, we were able to use it for more than four three-hour online Dungeons & Dragons games at relatively low power, turning it off in between uses, before it needed to be recharged.

The polarization of light reflected and transmitted at an interface between two media or at a thin-film multilayer coating can be altered dramatically. These two cases are considered below.

That is, E appears to oscillate along a line oriented at 45° with respect to the x axis. Hence this situation is called linear polarization.Notice that equivalently we could view the wave at a particular location (“fixed position”) and watch its amplitude evolve with time. Suppose we sit at the position z = 0. Then we see that