Asphericlenses meaning

In the same manner, two Polaroid filters oriented with their polarization axes perpendicular to each other will block all the light. Now that's a pretty cool observation that could never be explained by a particle view of light.

The transverse nature of an electromagnetic wave is quite different from any other type of wave that has been discussed in The Physics Classroom Tutorial. Let's suppose that we use the customary slinky to model the behavior of an electromagnetic wave. As an electromagnetic wave traveled towards you, then you would observe the vibrations of the slinky occurring in more than one plane of vibration. This is quite different than what you might notice if you were to look along a slinky and observe a slinky wave traveling towards you. Indeed, the coils of the slinky would be vibrating back and forth as the slinky approached; yet these vibrations would occur in a single plane of space. That is, the coils of the slinky might vibrate up and down or left and right. Yet regardless of their direction of vibration, they would be moving along the same linear direction as you sighted along the slinky. If a slinky wave were an electromagnetic wave, then the vibrations of the slinky would occur in multiple planes. Unlike a usual slinky wave, the electric and magnetic vibrations of an electromagnetic wave occur in numerous planes. A light wave that is vibrating in more than one plane is referred to as unpolarized light. Light emitted by the sun, by a lamp in the classroom, or by a candle flame is unpolarized light. Such light waves are created by electric charges that vibrate in a variety of directions, thus creating an electromagnetic wave that vibrates in a variety of directions. This concept of unpolarized light is rather difficult to visualize. In general, it is helpful to picture unpolarized light as a wave that has an average of half its vibrations in a horizontal plane and half of its vibrations in a vertical plane.

Asphericlenses glasses

2. Light becomes partially polarized as it reflects off nonmetallic surfaces such as glass, water, or a road surface. The polarized light consists of waves vibrate in a plane that is ____________ (parallel, perpendicular) to the reflecting surface.

Referring to the above question, the glare is the result of a large concentration of light aligned parallel to the water surface. To block such plane-polarized light, a filter with a vertically aligned polarization axis must be used.

Polarization can also occur by the refraction of light. Refraction occurs when a beam of light passes from one material into another material. At the surface of the two materials, the path of the beam changes its direction. The refracted beam acquires some degree of polarization. Most often, the polarization occurs in a plane perpendicular to the surface. The polarization of refracted light is often demonstrated in a Physics class using a unique crystal that serves as a double-refracting crystal. Iceland Spar, a rather rare form of the mineral calcite, refracts incident light into two different paths. The light is split into two beams upon entering the crystal. Subsequently, if an object is viewed by looking through an Iceland Spar crystal, two images will be seen. The two images are the result of the double refraction of light. Both refracted light beams are polarized - one in a direction parallel to the surface and the other in a direction perpendicular to the surface. Since these two refracted rays are polarized with a perpendicular orientation, a polarizing filter can be used to completely block one of the images. If the polarization axis of the filter is aligned perpendicular to the plane of polarized light, the light is completely blocked by the filter; meanwhile the second image is as bright as can be. And if the filter is then turned 90-degrees in either direction, the second image reappears and the first image disappears. Now that's pretty neat observation that could never be observed if light did not exhibit any wavelike behavior.

The first filter will polarize the light, blocking one-half of its vibrations. The second filter will have no affect on the light. Being aligned parallel to the first filter, the second filter will let the same light waves through.

Figure: Comparison of the three most frequent surface form imperfections (form error, waviness, and surface roughness) according to shape and type of deviation

Aspherical lens

1. Suppose that light passes through two Polaroid filters whose polarization axes are parallel to each other. What would be the result?

Polarization is also used in the entertainment industry to produce and show 3-D movies. Three-dimensional movies are actually two movies being shown at the same time through two projectors. The two movies are filmed from two slightly different camera locations. Each individual movie is then projected from different sides of the audience onto a metal screen. The movies are projected through a polarizing filter. The polarizing filter used for the projector on the left may have its polarization axis aligned horizontally while the polarizing filter used for the projector on the right would have its polarization axis aligned vertically. Consequently, there are two slightly different movies being projected onto a screen. Each movie is cast by light that is polarized with an orientation perpendicular to the other movie. The audience then wears glasses that have two Polaroid filters. Each filter has a different polarization axis - one is horizontal and the other is vertical. The result of this arrangement of projectors and filters is that the left eye sees the movie that is projected from the right projector while the right eye sees the movie that is projected from the left projector. This gives the viewer a perception of depth.

Asphericcontact lenses

Correction of aberrationsUsing spherical lenses, imaging errors, so-called spherical aberrations, inevitably occur (see figure on the top of this page). This results in a slightly blurred, out-of-focus image because the light rays do not converge on the optical axis at one focal point. The rays are refracted to different degrees depending on their distance from the optical axis: those that pass through the edges of the lens are refracted more strongly. Aspheric optics are rotationally symmetric, with one or more non-spherical surfaces that deviate from the shape of a sphere. The surfaces change their radius of curvature with increasing distance from the optical axis. These properties allow the light rays to converge in one point and the spherical aberration to be corrected. Thanks to modern production technologies, asphericon is able to manufacture aspheric lenses with highest precision even in series.Mathematical description of an aspheric lensDue to the different shape to the sphere, a more complex description of the rotationally symmetric aspheric lens is required. Traditionally, aspheric lens surface profiles can be described with the following formula. z ( h ) = h 2 R ( 1 + 1 − ( 1 + k ) h 2 R 2 ) + ∑ i = 2 n A 2 i h 2 i z = Sag of surfaceh = Distance perpendicular to the optical axis (height of incidence)R = Radiusk = Conic constantA2i = Aspheric coefficients of the correction polynomialIf the respective aspheric coefficient of a rotationally symmetric asphere is zero, the resulting surface profile is considered conical. Depending on the conic constant k, one of the following conic sections serves as a surface shape description:k = 0 - Spherek > -1 - Ellipsoidk = -1 - Parabolak < -1 - HyperbolaWith ISO 10110, which was renewed in 2015, there is an alternative to the traditional description of aspheric surfaces. Based on orthonormal polynomials, it can be used to model the real difference in deflection to the best-fitted spherical shape of the aspherical lens. The new formula also includes the surface quotient Qm and reads: z ( h ) = h 2 R [ 1 + 1 − h 2 R 2 ] + ( h h 0 ) 2 [ 1 − ( h h 0 ) 2 ] 1 − ( h R ) 2 ∑ m = 0 N A m ∗ Q m ( h 2 h 0 2 ) The revised formula offers far-reaching advantages that simplify the surface description. One major advantage is that fewer significant digits are required to describe the surface profile. A further advantage is the maximum sag departure deflection deviation. This can be estimated by multiplying the largest coefficient Am by the maximum amplitude for the order of this coefficient.Aspheric surface profileFigure: Comparison of the three most frequent surface form imperfections (form error, waviness, and surface roughness) according to shape and type of deviationThe three most reported surface shape imperfections are:• Surface form error,• Waviness and• Surface roughness.They represent deviations of the real surface from the ideal surface, as for the aspheric lens. The parameters used to describe the surface profile allow a prediction of the quality of a manufactured lens profile after processing. A high surface quality can among other things be achieved by a high process stability.Surface form errorThe form error describes the difference between the lowest and highest point of the test surface. Metaphorically speaking, it refers from mountain to valley, therefore the form error is given by the PV value, peak-to-valley. The PV value is one of the most important surface specifications for inspecting the surface of an aspheric lens. It is evaluated in waves or in fringes. It is also possible to specify it as an RMS or micrometer deviation. The RMS value (Root Mean Square) describes the mean square difference between the ACTUAL and the TARGET surface, taking into account the area of the defect.WavinessWaviness errors on an aspheric lens can be caused, for example, by polishing tools during the machining process. This surface deviation is therefore application specific. The waviness has a longer wavelength than the roughness, which is why the short wavelengths are filtered out for their examination. Only low frequencies may pass. It is often also referred to as the inclination error, which is examined over a defined length. A specification of waviness tolerances is only necessary if the waviness has an effect on the optical task of the aspheric lens.Surface roughnessSurface roughness describes smallest irregularities on the optical surface. Therefore, only the short wavelengths are examined for analysis and low frequencies are filtered out. Surface roughness is a dimension for the quality of polishing processes. The effect on optical applications of the aspheric lens can often be decisive. For example, a high degree of roughness can lead to a faster wear of the aspherical lens as soon as high powers, such as those of a laser, act on it. In addition, scattering reduces the quality of the measurement results, which is why low surface roughness is considered a high-quality feature. In industries such as metrology or aerospace this is of importance. The determination of surface roughness is part of the manufacturing process, especially for high-quality aspheric lenses.asphericons standards in the production of high-precision opticsasphericon has specialized in the production of aspheric lenses by grinding, polishing, diamond turning and high-end finishing. In this process a blank is subjected to various work steps:• Grinding or diamond turning for shaping,• Polishing the ground aspheric lens,• Measurement for form and surface inspection,• Measurement and processing by means of high-end finishing.Grinding and polishingBlanks are already shaped lenses and the starting material for the further process to produce an aspheric lens. In the first work step, the blank is ground to give it its desired shape. Various grinding tools and technologies are used for this complex process. The ability to simulate the individual process steps using asphericon’s unique CNC control software allows for an unprecedented realization, for high flexibility and reliability during the entire process. In the following, the polishing process is an important part in the production of an aspheric lens. Step by step, the surface is reworked to achieve the desired requirements (e.g. the surface shape deviation). Polishing can be done by machining with geometrically undefined, very fine grain, but also by chemical removal. A finished polished lens has a bright surface without pores and depth cracks as well as the desired shape accuracy and surface quality.Diamond TurningThe diamond turning process is an alternative machining method for shaping an aspheric lens. A monocrystalline diamond is used to machine the lens surface. In contrast to grinding tools, this is much smaller and more filigree. Due to its high hardness, ultra-precise machining of the lens is possible, resulting in an improved surface quality. By means of diamond turning, non-ferrous metals, nickel-phosphorus layers, crystals, and IR-glasses can be machined, in addition to an aspheric lens made of plastic.Measurement of the aspheric lensThe full-surface precise measurement of aspheric lens and other optics at asphericon includes tactile and optical methods. The subsequent measurement of an aspheric lens is used to check the shape and surface to detect and correct any deviations. An aspheric lens can be measured tactile and optical or contactless, depending on the processing state and accuracy. The full-surface precise measurement of aspheric lenses and other optics at asphericon includes:• Tactile measuring methods up to diameters of 260 mm• Full-surface, non-contact measurement up to 420 mm• Non-contact center thickness measurement• Roughness measurement Ra < 0.5 nm RMS, measuring field up to 1x1 mm• Measurement of freeforms, shape and positional tolerances, roughness• Measurement/positional check of mounts, mounted aspheric lenses and complete systems• Confocal 3D defect characterizationTactile measurementWith tactile measuring methods, the surface of an optical component is scanned with a probe. Differences in height between the scanned surface section and the nominal surface of the measured object are determined. The determined data of the height differences are then analysed and evaluated by a software. A rigid touch probe system and a contact pressure of the probe ball that is as constant as possible are required for the exact determination of the surface contour. Among more complex tactile measuring devices are the 3D coordinate measuring system and the form tester Mahr MFU, both used at asphericon.Interferometric measurementMuch more common are interferometric measuring methods for testing an aspheric surface. Interferometers are based on the principle of interference, i.e. the superposition of two coherent light waves (the test beam and the reference beam). A characteristic interference fringe pattern is produced which is used to evaluate the optical surface. The interference fringes are differences in intensity caused by a phase shift of the test wave to the reference wave. This means that surface deviations of the aspheric lens from the ideal shape become visible. To measure an aspheric lens, a computer-generated hologram (CGH) is sometimes additionally required to generate the aspheric reference wavefront. Such a measurement is repeated in phase-shifting measurement methods with several shifts of the reference surface, resulting in a full-surface error map of the aspheric lens to be measured. The MarOpto TWI 60 measuring system, which has been used by asphericon since 2017, is considered a pioneer in optical metrology and measures without CGHs. The modern interferometer measures using differently tilted wave fronts and thus inspects aspheric lenses and freeforms in seconds.Application examples of the aspheric lensThe use of an aspheric lens is mainly based on its advantages compared to a spherical lens. The biggest benefit is the correction of aberrations resulting in better imaging properties.Telescopes today, for example, are almost always aspherical, especially those with larger diameters. Aspheric elements are also used in zoom lenses. Not only the system size is reduced but also the imaging quality is increased compared to applications with spherical lenses.For star observation, but also in the aerospace industry, aspheric lenses can be used. The Sentinel-4 satellite, for example, contains aspheric optics from asphericon in its spectrometers. For use in space, the optics do not only need excellent optical properties, but also have to withstand extreme environmental conditions. Here you can learn more about Sentinel-4.Another field of application is laser beam shaping, such as the generation of Top-Hat beam profiles. In a beam shaping system with two aspheric lenses for Top-Hat light distribution the first lens is used to redistribute the incoming laser beams (Gaussian distribution) in such a way that a homogeneous intensity distribution is achieved at a certain distance. The second lens collimates the beam and as a result, the characteristic Top-Hat distribution is created. These aspheric applications are of interest in material processing (e.g. cutting of metal) and also in medical applications (e.g. ophthalmology). A detailed description of laser beam shaping with aspheric lenses and other application examples can be found in our blog.Imaging ophthalmological-instrumental procedures also work with aspheric lenses. Installed in special instruments, they support preventive and postoperative examinations, treatments, and diagnoses of the eye, such as ocular fundus examinations using a slit lamp or fundus camera. In addition to high-resolution imaging, aspheric lenses guarantee a more compact design of ophthalmological observation systems as well as very good imaging qualities.In industrial areas such as manufacturing, quality control or robotics, high-quality camera systems are required. These are equipped with lenses, which can be based on aspheric lenses. Even under the most difficult conditions, such as high temperatures under constant use, the lenses must withstand. Their task is to focus the light scattered by the object onto a light-sensitive sensor. By passing through several different process steps, important data is transported to its destination.A relatively new application for aspheric lenses on the market is the field of metrology. Their use can significantly reduce the total number of lenses used in a Fizeau transmission sphere and increases the measuring range. Another advantage: the transmission sphere is also significantly lighter thanks to the use of fewer lenses. For information on the use of aspheric lenses in transmission spheres, please refer to the reference for our aspheric Fizeau lens.

A Polaroid filter is able to polarize light because of the chemical composition of the filter material. The filter can be thought of as having long-chain molecules that are aligned within the filter in the same direction. During the fabrication of the filter, the long-chain molecules are stretched across the filter so that each molecule is (as much as possible) aligned in say the vertical direction. As unpolarized light strikes the filter, the portion of the waves vibrating in the vertical direction are absorbed by the filter. The general rule is that the electromagnetic vibrations that are in a direction parallel to the alignment of the molecules are absorbed.

Based on an unique technology, asphericon is able to produce aspherical optics with a surface form deviation (RMSi) from up to 0,01 µm. In cooperation with our customers we are developing and producing suitable solutions for a big variety of optical lenses – from the prototype to series. Choose an individual Custom solution or use the innovative diversity of our stocked aspheric lens from the StockOptics product line. a|Aspheres are available in our web shop with surface form deviations of RMSi ≤ 0.5 μm and RMSi <0.3 μm. Due to precise focusing properties, all optics and components from asphericon are suitable for a wide variety of applications.

It is possible to transform unpolarized light into polarized light. Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization. There are a variety of methods of polarizing light. The four methods discussed on this page are:

The three most reported surface shape imperfections are:• Surface form error,• Waviness and• Surface roughness.They represent deviations of the real surface from the ideal surface, as for the aspheric lens. The parameters used to describe the surface profile allow a prediction of the quality of a manufactured lens profile after processing. A high surface quality can among other things be achieved by a high process stability.Surface form errorThe form error describes the difference between the lowest and highest point of the test surface. Metaphorically speaking, it refers from mountain to valley, therefore the form error is given by the PV value, peak-to-valley. The PV value is one of the most important surface specifications for inspecting the surface of an aspheric lens. It is evaluated in waves or in fringes. It is also possible to specify it as an RMS or micrometer deviation. The RMS value (Root Mean Square) describes the mean square difference between the ACTUAL and the TARGET surface, taking into account the area of the defect.WavinessWaviness errors on an aspheric lens can be caused, for example, by polishing tools during the machining process. This surface deviation is therefore application specific. The waviness has a longer wavelength than the roughness, which is why the short wavelengths are filtered out for their examination. Only low frequencies may pass. It is often also referred to as the inclination error, which is examined over a defined length. A specification of waviness tolerances is only necessary if the waviness has an effect on the optical task of the aspheric lens.Surface roughnessSurface roughness describes smallest irregularities on the optical surface. Therefore, only the short wavelengths are examined for analysis and low frequencies are filtered out. Surface roughness is a dimension for the quality of polishing processes. The effect on optical applications of the aspheric lens can often be decisive. For example, a high degree of roughness can lead to a faster wear of the aspherical lens as soon as high powers, such as those of a laser, act on it. In addition, scattering reduces the quality of the measurement results, which is why low surface roughness is considered a high-quality feature. In industries such as metrology or aerospace this is of importance. The determination of surface roughness is part of the manufacturing process, especially for high-quality aspheric lenses.

The most common method of polarization involves the use of a Polaroid filter. Polaroid filters are made of a special material that is capable of blocking one of the two planes of vibration of an electromagnetic wave. (Remember, the notion of two planes or directions of vibration is merely a simplification that helps us to visualize the wavelike nature of the electromagnetic wave.) In this sense, a Polaroid serves as a device that filters out one-half of the vibrations upon transmission of the light through the filter. When unpolarized light is transmitted through a Polaroid filter, it emerges with one-half the intensity and with vibrations in a single plane; it emerges as polarized light.

Choose between asphericon a|High-NA, a|Low-NA and a|UV-grade fused silica as well as up to three different quality levels (Precision, Ultra and BeamTuning). Thanks to CNC polishing and grinding this aspheric lens meets the highest demands on production quality and tolerance:

AsphericLenses price

Aspheres have much better imaging properties than spherical lenses thanks to the surface geometry that deviates from a sphere. The main benefit is the ability to correct spherical aberrations. The total number of optical elements in an optical system can be reduced by using an aspheric lens. This enables a significantly more compact and efficient setup than is the case for a comparable system with spherical lenses.

Looking for a custom solution? Discover our customized aspheres with unsurpassed surface quality and following specifications::

RMSi [nm]Diameter [mm]EFL [mm]NAλDesign [nm]MaterialCoatingAllAllAllAllAllAllAllProduct CodeRMSi [nm]Wavefront RMS [nm]Diameter [mm]EFL [mm]NAf/dWD [mm]λDesign [nm]MaterialScratch-DigCoatingPrice uncoatedPrice coatedAHM12-10-U-U1007812.5100.550.807.6780S-LAH6460-40A / B / C479.00528.00Quote AHM15-12-U-U1007815120.550.809.0780S-LAH6460-40A / B / C504.00564.00Quote AHM18-15-U-U1007818150.530.8311.5780S-LAH6460-40A / B / C534.00609.00Quote AHM20-18-U-U1007820180.490.9014.0780S-LAH6460-40A / B / C560.00628.00Quote AHM25-20-U-U1007825200.540.8015.7780S-LAH6460-40A / B / C588.00659.00Quote ALM12-25-U-U1005112.5250.252.022.4780N-BK760-40A / B / C479.00528.00Quote ALM25-50-U-U1005125500.232.046.0780N-BK760-40A / B / C588.00659.00Quote AFM12-10-U-U30014012.5100.580.8335.7355Fused Silica20-20A / B / C / X / Y / K / L / M523.00571.00Quote AFM12-15-U-U30014012.5150.391.212.3285Fused Silica20-20A / B / C / X / Y / K / L / M514.00562.00Quote AFM12-20-U-U30014012.5200.291.617.3285Fused Silica20-20A / B / C / X / Y / K / L / M514.00562.00Quote AFM25-17-U-U3001402517.50.640.710.0355Fused Silica20-20A / B / C / X / Y / K / L / M737.00847.00Quote AFM25-20-U-U30014025200.560.812.6355Fused Silica20-20A / B / C / X / Y / K / L / M706.00816.00Quote AFM25-25-U-U30014025250.481.017.0285Fused Silica20-20A / B / C / X / Y / K / L / M684.00795.00Quote AFM25-30-U-U30014025300.391.223.3285Fused Silica20-20A / B / C / X / Y / K / L / M636.00709.00Quote AFM25-40-U-U30014025400.291.634.6285Fused Silica20-20A / B / C / X / Y / K / L / M636.00709.00Quote AFM25-50-U-U30014025500.232.045.1355Fused Silica20-20A / B / C / X / Y / K / L / M636.00709.00Quote AFM25-75-U-U30014025750.153.070.9355Fused Silica20-20A / B / C / X / Y / K / L / M618.00709.00Quote AFM25-100-U-U300140251000.114.096.3355Fused Silica20-20A / B / C / X / Y / K / L / M636.00709.00Quote AFM25-50-D-U201025500.232.045.1355Fused Silica20-20A / B / C / X / Y / K / L / M950.001058.00Quote AFM25-75-D-U201025750.153.070.9355Fused Silica20-20A / B / C / X / Y / K / L / M950.001058.00Quote AFM25-100-D-U2010251000.114.096.3355Fused Silica20-20A / B / C / X / Y / K / L / M950.001058.00Quote Prices are valid per piece and in USD. Sales only to commercial customers. All prices are exclusive of VAT.

Asphericlenses vs spherical

The alignment of these molecules gives the filter a polarization axis. This polarization axis extends across the length of the filter and only allows vibrations of the electromagnetic wave that are parallel to the axis to pass through. Any vibrations that are perpendicular to the polarization axis are blocked by the filter. Thus, a Polaroid filter with its long-chain molecules aligned horizontally will have a polarization axis aligned vertically. Such a filter will block all horizontal vibrations and allow the vertical vibrations to be transmitted (see diagram above). On the other hand, a Polaroid filter with its long-chain molecules aligned vertically will have a polarization axis aligned horizontally; this filter will block all vertical vibrations and allow the horizontal vibrations to be transmitted.

A light wave is an electromagnetic wave that travels through the vacuum of outer space. Light waves are produced by vibrating electric charges. The nature of such electromagnetic waves is beyond the scope of The Physics Classroom Tutorial. For our purposes, it is sufficient to merely say that an electromagnetic wave is a transverse wave that has both an electric and a magnetic component.

Polarization of light by use of a Polaroid filter is often demonstrated in a Physics class through a variety of demonstrations. Filters are used to look through and view objects. The filter does not distort the shape or dimensions of the object; it merely serves to produce a dimmer image of the object since one-half of the light is blocked as it passed through the filter. A pair of filters is often placed back to back in order to view objects looking through two filters. By slowly rotating the second filter, an orientation can be found in which all the light from an object is blocked and the object can no longer be seen when viewed through two filters. What happened? In this demonstration, the light was polarized upon passage through the first filter; perhaps only vertical vibrations were able to pass through. These vertical vibrations were then blocked by the second filter since its polarization filter is aligned in a horizontal direction. While you are unable to see the axes on the filter, you will know when the axes are aligned perpendicular to each other because with this orientation, all light is blocked. So by use of two filters, one can completely block all of the light that is incident upon the set; this will only occur if the polarization axes are rotated such that they are perpendicular to each other.

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Polarization also occurs when light is scattered while traveling through a medium. When light strikes the atoms of a material, it will often set the electrons of those atoms into vibration. The vibrating electrons then produce their own electromagnetic wave that is radiated outward in all directions. This newly generated wave strikes neighboring atoms, forcing their electrons into vibrations at the same original frequency. These vibrating electrons produce another electromagnetic wave that is once more radiated outward in all directions. This absorption and reemission of light waves causes the light to be scattered about the medium. (This process of scattering contributes to the blueness of our skies, a topic to be discussed later.) This scattered light is partially polarized. Polarization by scattering is observed as light passes through our atmosphere. The scattered light often produces a glare in the skies. Photographers know that this partial polarization of scattered light leads to photographs characterized by a washed-out sky. The problem can easily be corrected by the use of a Polaroid filter. As the filter is rotated, the partially polarized light is blocked and the glare is reduced. The photographic secret of capturing a vivid blue sky as the backdrop of a beautiful foreground lies in the physics of polarization and Polaroid filters.

Discover our extensive range of individual and stocked aspherical optics, assemblies and optical systems - discover the possibilities we offer in-house for your aspheric lenses:

Polarization has a wealth of other applications besides their use in glare-reducing sunglasses. In industry, Polaroid filters are used to perform stress analysis tests on transparent plastics. As light passes through a plastic, each color of visible light is polarized with its own orientation. If such a plastic is placed between two polarizing plates, a colorful pattern is revealed. As the top plate is turned, the color pattern changes as new colors become blocked and the formerly blocked colors are transmitted. A common Physics demonstration involves placing a plastic protractor between two Polaroid plates and placing them on top of an overhead projector. It is known that structural stress in plastic is signified at locations where there is a large concentration of colored bands. This location of stress is usually the location where structural failure will most likely occur. Perhaps you wish that a more careful stress analysis were performed on the plastic case of the CD that you recently purchased.

Disadvantages ofasphericlenses

asphericon has specialized in the production of aspheric lenses by grinding, polishing, diamond turning and high-end finishing. In this process a blank is subjected to various work steps:• Grinding or diamond turning for shaping,• Polishing the ground aspheric lens,• Measurement for form and surface inspection,• Measurement and processing by means of high-end finishing.Grinding and polishingBlanks are already shaped lenses and the starting material for the further process to produce an aspheric lens. In the first work step, the blank is ground to give it its desired shape. Various grinding tools and technologies are used for this complex process. The ability to simulate the individual process steps using asphericon’s unique CNC control software allows for an unprecedented realization, for high flexibility and reliability during the entire process. In the following, the polishing process is an important part in the production of an aspheric lens. Step by step, the surface is reworked to achieve the desired requirements (e.g. the surface shape deviation). Polishing can be done by machining with geometrically undefined, very fine grain, but also by chemical removal. A finished polished lens has a bright surface without pores and depth cracks as well as the desired shape accuracy and surface quality.Diamond TurningThe diamond turning process is an alternative machining method for shaping an aspheric lens. A monocrystalline diamond is used to machine the lens surface. In contrast to grinding tools, this is much smaller and more filigree. Due to its high hardness, ultra-precise machining of the lens is possible, resulting in an improved surface quality. By means of diamond turning, non-ferrous metals, nickel-phosphorus layers, crystals, and IR-glasses can be machined, in addition to an aspheric lens made of plastic.

3. Consider the three pairs of sunglasses below. Identify the pair of glasses is capable of eliminating the glare resulting from sunlight reflecting off the calm waters of a lake? _________ Explain. (The polarization axes are shown by the straight lines.)

Our model of the polarization of light provides some substantial support for the wavelike nature of light. It would be extremely difficult to explain polarization phenomenon using a particle view of light. Polarization would only occur with a transverse wave. For this reason, polarization is one more reason why scientists believe that light exhibits wavelike behavior.

Unpolarized light can also undergo polarization by reflection off of nonmetallic surfaces. The extent to which polarization occurs is dependent upon the angle at which the light approaches the surface and upon the material that the surface is made of. Metallic surfaces reflect light with a variety of vibrational directions; such reflected light is unpolarized. However, nonmetallic surfaces such as asphalt roadways, snowfields and water reflect light such that there is a large concentration of vibrations in a plane parallel to the reflecting surface. A person viewing objects by means of light reflected off of nonmetallic surfaces will often perceive a glare if the extent of polarization is large. Fishermen are familiar with this glare since it prevents them from seeing fish that lie below the water. Light reflected off a lake is partially polarized in a direction parallel to the water's surface. Fishermen know that the use of glare-reducing sunglasses with the proper polarization axis allows for the blocking of this partially polarized light. By blocking the plane-polarized light, the glare is reduced and the fisherman can more easily see fish located under the water.

A picket-fence analogy is often used to explain how this dual-filter demonstration works. A picket fence can act as a polarizer by transforming an unpolarized wave in a rope into a wave that vibrates in a single plane. The spaces between the pickets of the fence will allow vibrations that are parallel to the spacings to pass through while blocking any vibrations that are perpendicular to the spacings. Obviously, a vertical vibration would not have the room to make it through a horizontal spacing. If two picket fences are oriented such that the pickets are both aligned vertically, then vertical vibrations will pass through both fences. On the other hand, if the pickets of the second fence are aligned horizontally, then the vertical vibrations that pass through the first fence will be blocked by the second fence. This is depicted in the diagram below.