# Bienial color

Introduction

e o light intensity most of the light generated in the crystal by natural light is incident equal

## . However, there are some crystals of two very different absorption of light refraction, this property is called dichroism. Crystals can be produced by using two dichroic polarizer.

dichroism refers to a substance depends on the optical absorption coefficient of the state of polarization of incident light. As early as 1815 Byatt (the Biot) found using tourmaline crystal dichroic di (dichorism) which produced the first polarizer tourmaline.

## explained

we know, a parallel light beam can be regarded as a natural light is made on any two mutually orthogonal directions perpendicular to the propagation direction of polarization of the two disparate the amplitude of the light beam and other components. After selecting a crystal main vibration direction as the vibration direction of the two partial beams, if E is the amplitude of each of the two partial beam into the wafer, the wafer in the propagation distance L, the amplitude thereof:

< p>

is a quasi-monochromatic incident light is assumed, the average frequency of w. Propagation velocity v. Then

Total Strength:

formula

. If two exponential decay K 1 , K 2 large difference, then a relatively thin material is sufficient to transform the incident unpolarized beam is approximately linearly polarized beam, i.e., plays wafer acts as a polarizer. If the
// "K , for example, stretching the sheet in the H direction //, the direction ⊥ through its vibration axis.

Knowledge: birefringent crystal

ray of monochromatic light (1), can generally produce two beams refracted light refracted at the crystal surface, this phenomenon It is called birefringence. Two refracted light beams, there is a bundle always follow the law of refraction, referred to as ordinary light, indicated by symbol O; further beam generally does not comply with the law of refraction, referred to as the extraordinary light, indicated by symbol e. e o light is linearly polarized light.

To illustrate the vibration direction and the propagation direction of light and e o light, some special need to know the direction of the plane and the crystal:

axis - within a specific crystal direction, when the light propagating in this direction, birefringence does not occur, and o is the speed of light and e is equal to the light propagation. Only a crystal axis direction is referred to as a uniaxial crystal (e.g., calcite, quartz, ruby, etc.). Two optical axis direction of the crystal, called biaxial crystal (such as mica, aragonite, sapphire, etc.).

main plane - a plane consisting of o-light optical axis o said main plane; e surface of the light axis of said composition e main plane. O oscillation direction of the electric vector of the light perpendicular to the main plane of o, e-light electric vector vibration direction of the main plane in e.

main section - by the optical axis and the surface normal of the surface of the crystals. Can be shown, when the light incident surface in the main section, light and e o are within the main section of the light, then the main section of the main plane of light is a common e o light.

crystal causes birefringence, wherein the optically anisotropic crystal. It is evident from the electromagnetic theory, for a given direction of the optical axis of the crystal in addition, it allows the electric vector of the beam two mutually perpendicular linearly polarized light travel at different speeds. For uniaxial crystal, the speed of a beam of light which does not change with the direction of propagation, that is o light. It is a spherical wave surface. The other beam of light propagation direction is changed with the speed, this is the e-light, it is a wavefront to the optical axis symmetric ellipsoid of revolution, which equation is

wherein

o is the refractive index,
e is the refractive index of the light propagation direction perpendicular to the optical axis,
is e and the optical axis angle of the light, c is the speed of light in vacuum. Crystal negative (
), and n-crystal (
) o of light, e optical wavefront are shown in Fig. Using the concept of the wave surface, the direction of refraction light crystals e o light by Huygens mapping method can be obtained.

It should be noted that the propagation velocity and direction of the crystal in the e-rays generally to its speed and direction of propagation of the wavefront (wavefront along the surface normal direction) different from the latter as a normal line speed . Normal endpoint velocity vector locus depicts a normal line, that the wave surface geometry shown in Figure 3, which equation is

formula the

denotes the normal speed,
represents the angle between the velocity vector and the normal to the optical axis. Shape of the space plane is normal to the optical axis as a symmetry axis of the oval surface.

using crystal birefringence, can be made into a polarizing prism, so that we get directly from natural polarized light.

e o light intensity most of the light generated in the crystal by natural light is incident equal. However, there are some crystals of two very different refraction of light absorption, but this property is called dichroism. Crystals can be produced by using two dichroic polarizer.

## in the microscopic field

in the microscopic field, the light absorption rate is not a scalar molecule, but has certain directivity (vector). If the absorption coefficient of three different directions, the difference of the two coefficients is called dichroism. Macroscopic absorption rate performance two dichroic absorption coefficient with directivity, both with two related two dichroic dichroic molecules on a macroscopic, also associated with the molecular arrangement, it can be used as the dichroic degree of orientation A method of characterizing method. Further, some of the functional groups on the macromolecular chains having a certain direction, different from the vibration direction of the infrared light it will exhibit dichroism, called infrared dichroism.

## Applications

color polarizing plate produced:

aligned wire grid Kui sulfate and iodine and "end product, iodine directing embedded on a transparent plastic film and certain dyes have good dichroism. Thus they are made of different uses polarizers good material.

there are significant differences in the absorption direction e 0 direction iodine, and with et al .land wavelength variation using this difference H is polarized generally produced brown or bluish in J. after numerous experiments we found that certain dyes containing elongated molecules are also quite good dichroism can use it as the manufacture of other color polarizing plate with:.

+ direct silver direct red, red polarizing plate manufactured

+ chrysophenine direct red brown, yellow polarizer for producing

direct dark green, green polarizer manufacturing

directly producing a purplish red purple polarizer

dye solution was prepared, except that the corresponding outer dye, and adding a small amount of hydroxide sodium

the dye for producing a color polarizing film is generally steps: first, a dye solution is heated to a high temperature, and then put into a transparent plastic film, the dye molecules diffuse into the sheet, and then stretching that the final unidirectionally aligned dye molecules do. there is also a rubbing method, a dye and a transparent plastic film directly on the surface friction, then the dye molecules attached on the film parallel to the same effect.

may be a transparent plastic film with polyethylene producing vinyl alcohol manufactured H dip sheet iodine, stretching, bonding process is equally applicable to manufacturing a color polarizing plate. but this time with a dye instead of iodine. Further, in terms of adhesion, colorless and transparent optical epoxy resin plastic from ultraviolet, visible and infrared spectral transmittance quite good, and good resistance to dielectric properties, a polarizer is preferable adhesive. when used to improve the room temperature around 30 ℃, preheated to the adhesive member about 40 ℃, at this time, the viscosity of epoxy glue drops 100 (mpa · s), it does not feel sticky difficult and H as the polarizing plate, the color polarizing dye molecules of increase more, more polarization plate high, the light transmission efficiency is reduced corresponding sheet.

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