What is isochromatic fringe pattern?
[¦ī·sō·krə′mad·ik ′frinj ‚pad·ərn] (optics) A pattern of bands, each of uniform color, observed when a plate is placed in a polariscope and subjected to stress, making it birefringent.
What are Isoclinic and Isochromatic?
Isochromatic fringes are obtained using monochromatic light, whereas isoclinic fringes are obtained using white light. b. Isoclinic fringes are obtained when the principal stress direction coincides with the polarisation of the polariser; isochromatic fringes are lines of constant stress difference.
What is a photoelastic material?
A photoelastic material is one that has a stress dependent refractive index. When placed between crossed polarizers, the rotation of the polarized light by the stress field in the material generates a fringe pattern displaying contours of equal stress.
What is photoelasticity explain?
Photoelasticity describes changes in the optical properties of a material under mechanical deformation. It is a property of all dielectric media and is often used to experimentally determine the stress distribution in a material, where it gives a picture of stress distributions around discontinuities in materials.
What is photoelastic coefficient?
The photoelastic effect describes the coupling between light and sound in terms of the overall intensity and polarization properties of light scattering1. This effect has been applied to study stress distribution in semiconductor systems and lattice-mismatched semiconductor heterostructures.
What is a polariscope used for?
The polariscope is an optical inspection device used to detect internal stresses in glass and other transparent materials such as plastics, synthetic resins, etc. A polariscope is composed chiefly of a light source and two crossed polarized lenses such as Polaroid {{Registered Trademark}}.
What is Isoclinic?
Definition of isoclinic line : a line on a map or chart joining points on the earth’s surface at which a dip needle has the same inclination to the plumb line — compare aclinic line.
Where is photoelastic method used for?
The method is used primarily for analyzing two- dimensional plane problems, which is the emphasis in these notes. A method called stress freezing allows the method to be extended to three- dimensional problems. Photoelastic coatings are used to analyze surface stresses in bodies of complex geometry.
Why is photoelasticity used in engineering?
Photoelasticity is a handy tool for engineers to visualize areas where a structure might break due to high concentrations of stress. Plastics with birefringence properties reveal areas of strain within a structure in the form of colorful light fringes when viewed under polarized light.
What is a polariscope definition?
Who invented the polariscope?
Only two years later, in 1811, the French astronomer Dominique François Jean Arago invented the polariscope, an instrument that can determine whether or not light is polarized. Among other things, he discovered that lunar light is polarized.
What are Isogonic and Isoclinic lines?
Solution : Isogonic lines are the lines joining places of equal declination. Isoclinic lines are the lines joining places of equal dip/inclination. Isodynamic lines are the lines joining places of equal horizontal component of earth’s field. Loading Books. Answer.
What are Isogonic and Agonic lines?
An isogonic line is a line over the surface of the earth upon which magnetic declination is constant. An agonic line is an isogonic line upon which the declination is zero.
What is Fringe value?
A quantity used in photoelastic work, equal to the stress which must be applied to a material, in pounds per square inch (1 pound per square inch equals approximately 6.89476 kilopascals), to produce a relative retardation of 1 wavelength between the components of a linearly polarized light beam when the light passes …
What are the limitations of photoelasticity?
However, there are some disadvantages to this technique. Photoelasticity requires the production of a model of the actual part unless photoelastic coatings are used. Moreover, the calculations required to separate the principal stress values at a general interior point are very complicated.
What is called birefringence?
Birefringence is formally defined as the double refraction of light in a transparent, molecularly ordered material, which is manifested by the existence of orientation-dependent differences in refractive index.
What causes birefringent?
Modified proteins such as immunoglobulin light chains abnormally accumulate between cells, forming fibrils. Multiple folds of these fibers line up and take on a beta-pleated sheet conformation. Congo red dye intercalates between the folds and, when observed under polarized light, causes birefringence.
What is the function of a polariscope?
What are the isochromatic lines?
Isochromatics are the loci of the points along which the difference in the first and second principal stress remains the same. Thus they are the lines which join the points with equal maximum shear stress magnitude.
What is the fringe color?
The result is that the fringe color is the combination of two complementary colors, yellow and green. As the load and relative retardation continue to increase, the fringe color cycle is repeated, but the colors are not exactly the same as in the first cycle because of the simultaneous extinction of two or more colors.
What is the fringe color of white light spectrum?
However, the deep red color at the far end of the white light spectrum also has twice the wavelength of violet, and thus undergoes its first extinction simultaneously with the second extinction of violet. The result is that the fringe color is the combination of two complementary colors, yellow and green.
What is isochroous?
Of uniform color. Synonym (s): isochroous 2. Denoting two objects of the same color. 1. Of uniform color. 2. Denoting two objects of the same color. Possessing the same colour. Want to thank TFD for its existence?