Consider a model with variable beam focusing so you can sharpen or widen the highlighted area as needed. Tight, precise spotlights help isolate minute chart details from afar, ideal for data-dense projections. Meanwhile, flooding a broad swath in luminous red suits emphasizing general regions on a whiteboard to orient group brainstorming. Varying beam dispersion through adjustable focal lengths or interchangeable lenses prevents the same static circle from becoming monotonous.

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.

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.

Planepolarized lightenantiomers

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) 

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

Polarization oflightnotes PDF

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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.

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.

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.

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:

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.

Beware of equating higher price strictly with superiority across the board. In the journey to find the optimal balance of quality and affordability, recognize that cheaper models may actually excel in certain areas. For example, a basic red laser for $10 could feasibly be more visible, compact, or energy efficient than some feature-rich $50+ multiplayer. Set careful priorities for exactly what presentation enhancements would most directly improve your sessions and lift audience comprehension.

Color in presentations is crucial for visual appeal and communication. Each color corresponds to a specific wavelength, influencing mood and perception. Warm colors like red evoke energy, while cool colors like blue convey calmness. Careful selection of colors and wavelengths enhances engagement, comprehension, and retention, ensuring an effective and memorable presentation.

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.

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:

Polarized lightmeaning

The price and value of a laser pointer are influenced by all the factors mentioned above, as well as by your personal preferences, budget, and goals. You don't have to spend a fortune to get a good laser pointer, but you also don't want to waste your money on a cheap and unreliable one. You want a laser pointer that offers the best balance of performance, functionality, safety, and affordability. You also want a laser pointer that suits your presentation style, topic, and audience. A good way to determine the price and value of a laser pointer is to compare different options, weigh the pros and cons, and evaluate the benefits and drawbacks.

It is always essential to buy products from top rated brands like Logitech, Targus, and Kensington offer laser pointers designed specifically for presentations. Always read the reviews along with the warranty or guarantee period before making any purchases that best suits your model. Be aware of local rules & regulations regarding laser pointer usage, as some places may have restrictions on the power of laser pointers.

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.

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The color of a laser pointer depends on its wavelength, which is measured in nanometers (nm). The most common colors are red, green, and blue, but there are also other options like purple, yellow, and white. The color affects the visibility and contrast of the beam, as well as the cost and battery life of the device. Generally, green lasers are the most visible and popular, as they can be seen clearly in most lighting conditions and backgrounds. Red lasers are the cheapest and most energy-efficient, but they may be harder to see in bright or dark environments. Blue lasers are the most expensive and powerful, but they may also be the most dangerous and unstable.

What is planepolarized lightin Chemistry

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Plane-polarizedlightexamples

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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

Pay attention to battery life claims and real-world experiences. A laser pointer quickly becomes useless if the batteries drain too quickly, so verify expected battery life correlates to extensive actual usage accounts, not just manufacturer estimates. High quality lasers utilize circuitry regulating output calibration and timing to optimize power consumption rather than simply blasting non-stop at maximum levels.

I always discourage my clients from using a laser pointer. They are great for playing with cats (although I'm told they don't give the satisfaction of catching anything and it leaves cats depressed...) They leave humans depressed, too. When you're nervously whipping that tiny dot all over the place, your audience members' eyes are going crazy trying to keep up! Spend more time on your slides so they are simpler. Also you can use subtle animation, colors or other methods to highlight the areas of slides that you want your audience to focus their attention on.

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.

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

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

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.

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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.

Circularlypolarized 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

A higher mW (milliwatt) rating usually means a brighter beam hence, opt for a laser pointer with sufficient brightness. Green laser pointers are generally more visible than red ones. In a large auditorium, a laser pointer with a longer range is most suitable. It is always advisable to test the laser pointer in the actual presentation environment beforehand to ensure it meets your requirements and works well with your presentation style.

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

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Power and visibility are crucial for PowerPoint presentations (PPT). Power lies in compelling content, engaging visuals, and impactful delivery, capturing audience attention. Visibility ensures slides are clear, concise, and easily understood. Together, they amplify the effectiveness of a presentation, making it memorable and influential.

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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.

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.

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.

The power of a laser pointer determines how bright and visible the beam is. The higher the power, the more likely it is to reach far distances and penetrate different surfaces. However, higher power also means higher risk of eye damage, battery drain, and legal issues. The power of a laser pointer is measured in milliwatts (mW). For most presentation purposes, you don't need more than 5 mW, which is the maximum allowed by the FDA for general use. Anything above that may require special permits and safety precautions.

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

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For a presentation where quality and durability are essential, consider laser pointers from reputable brands like Logitech, Kensington, or Targus. Look for models with high-quality lasers that provide a clear, bright, and easily visible dot. Additionally, prioritize durability by choosing pointers with sturdy construction and reliable buttons. Wireless options with a good range can offer flexibility during presentations. Always read reviews to ensure the laser pointer meets your specific needs for both quality and durability.

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:

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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.

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:

Light up your presentation with the perfect laser pointer—where innovation meets illumination! When choosing a laser pointer for your presentation, go for one with a punch! Consider factors like brightness, color, and extra features. For a dynamic touch, opt for a green laser—it's often more eye-catching. Look for a pointer that doubles as a presentation remote, like Logitech's wireless models, to seamlessly navigate slides. Make sure it's durable, easy to handle, and has good battery life. Don't forget to check local regulations. Find the perfect balance between your budget and the laser's features, ensuring your presentation shines without breaking the bank!

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Think about how color contrast and visual impairments may affect visibility for your audience. For example, red and green beams can be indistinguishable for color blind attendees. Blue or magenta shades instead provide brighter, bolder highlights without chromatic confusion. Meanwhile, red and orange hues are generally highest contrast against light backgrounds, optimizing legibility even for seeing-impaired viewers.

PLEASE don't use laser pointers unless you're more skilled than Hawkeye and have got one with a gyroscope! A better approach is to design your slides so that you don't need one. If you need to highlight section X, either design the slide for only section X, or if you want to put X in context first (or another reason), show the full slide and then add a carefully crafted animation (or whatever) to highlight X. That might be by putting a background under it, circling it, or zooming in on it... whatever... but lasers are amateur, look distracting, and make you look like you're still in the 1970s.

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The quality and durability of a laser pointer depend on the materials, components, and craftsmanship of the device. You want a laser pointer that is made of sturdy and lightweight materials, such as metal or plastic. You also want a laser pointer that has high-quality components, such as diodes, lenses, circuits, and batteries. And you want a laser pointer that is well-built and tested, with no defects, flaws, or malfunctions. A good way to check the quality and durability of a laser pointer is to read reviews, compare specifications, and test it yourself before buying or using it.

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

Laser pointer that has the function to blank/blackout the screen during presentation will be very handy for trainers or facilitators ensuring that participants remain focused on discussions rather than being distracted by slide contents. This will be very helpful when trainers or facilitators are having deep discussion with participants.

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

Laser pointers are useful tools for highlighting key points, directing attention, and engaging your audience during a presentation. But not all laser pointers are created equal. Some are more powerful, versatile, and reliable than others. How do you choose the best one for your needs? Here are some factors to consider before you buy or use a laser pointer for your next presentation.

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This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

Linearlypolarized light

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.

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.

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.”

The features and functions of a laser pointer can vary depending on the model and brand. Some of the common features include buttons, switches, clips, grips, and indicators. These can affect the ease of use, comfort, and convenience of the device. Some of the common functions include modes, patterns, timers, and remote controls. These can enhance the versatility, creativity, and interactivity of the device. For example, you can use different modes to switch between a steady or flashing beam, different patterns to create shapes or symbols, timers to control the duration of the beam, and remote controls to operate your slides or other devices.

More powerful doesn't necessarily mean better when it comes to presentation pointers. A laser that is too intense can actually be distracting, overwhelming, or even dangerous if accidently shined at someone's eyes. Additionally, the brighter beams reflect more noticeably off of projection screens, obscuring content. Moderately powered lasers around 1-2 mW are typically sufficient for effectively highlighting slides and whiteboards without glare interference or eye safety concerns.

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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.

Selecting the ideal laser pointer involves balancing factors. It's tempting to just go for the cheap one (what can go wrong with something so simple?!). But you're wrong ❌ Here's how to navigate the choices to ensure you get the most value for your investment: ➜ Consider all Influencing Factors: Evaluate performance, functionality, safety, and affordability. ➜ Personal preferences matter: Align the laser pointer with your presentation style, topic, and audience. ➜ Budget wisely: While you don't need to overspend, be cautious of cheap, unreliable options. ➜ Compare options: Assess different laser pointers, weighing their pros and cons. ➜ Evaluate benefits and drawbacks: Scrutinize the overall advantages and limitations of each option.

Polarizedand unpolarizedlight

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

If you need a laser pointer either you want to play with a cat or your slides are way, way to complex. Never use a laser is the rule. Never.

Choosing a handy and comfortable functional laser pointer. Some pointers have ergonomic grips or buttons that make them easier to handle during a presentation with additional features such as multiple modes (continuous beam, pulsating, etc.) or built-in presentation controls (next/previous slide buttons).

Choosing the right laser pointer for your presentation can make a big difference in your delivery, impact, and results. By considering these factors, you can find the best laser pointer for your needs and make the most of your time.

Choosing the correct laser pointer for your presentation will help you communicate more effectively and engage your audience. -> Consider the laser pointer's brightness. A brighter laser is more noticeable in brightly lit areas or during daytime presentations. -> Choose a laser pointer with long battery life to avoid interruptions during your presentation. Rechargeable options might be convenient. -> Look for a user-friendly laser pointer with easily accessible buttons. Consider whether it has any additional functions, such as a built-in timer or a button that allows you to temporarily blank the screen. ->Evaluate your budget and look for a laser pointer that provides a decent balance of features within your price range.