Interactive Java Tutorials
Polarized Light Microscopy
Polarized light microscopy is a useful method to generate contrast in birefringent specimens and to determine qualitative and quantitative aspects of crystallographic axes present in various materials. The beautiful kaleidoscopic colors displayed by specimens under crossed polarizers arises as a result of the interference between light waves passing through the specimen. Addition of retardation plates (often termed compensators) can change the colors and hues of a material and provide information about specimen thickness and the order or birefringence. Use our interactive Java tutorials to explore how specimens are imaged with a polarized light microscope.
Polarized Light Microscopy - Caution! This applet is almost 150 Kilobytes in size resulting in downloads that may exceed 2 minutes on 28.8K modems. The tutorial simulates observation of various birefringent samples between crossed polarizers in a polarizing microscope. The virtual microscope stage is graduated in 10 degree increments and allows rotation through a full 360 degree turn of the sample. As the sample is rotated, birefringent elements of the sample undergo intensity changes (from brilliantly illuminated through total extinction) that reflect their orientation with respect to the virtual microscope polarizer and analyzer.
Polarized Light Microscopy with a Retardation Plate - Caution! This applet is almost 350 Kilobytes in size resulting in downloads that may exceed 2 to 3 minutes on 28.8K modems. This interactive tutorial demonstrates the effect of adding a 530 nanometer retardation plate between the polarizer and analyzer in a virtual polarizing microscope. Samples can be selected via a pull-down menu. Insertion of the retardation plate allows scientists to determine optical properties of the birefringent crystalline minerals.
Polarizer Rotation in Polarized Light Microscopy - Detection of dichroism or pleochroism can be difficult in materials that are only weakly birefringent or when thin preparations are utilized. In this case, it is often prudent to allow the specimen to maintain a stationary orientation with respect to the microscope optical axis while rotating the polarizer. This tutorial explores image changes during rotation of the polarizer in the light path of a polarized light microscope.
Polarizer Rotation with a First Order Retardation Plate - Insertion of a first-order retardation plate or compensator between the specimen and the analyzer changes the optical path difference of light passing through the specimen. Compensator plates providing a retardation of one entire wavelength (550 nanometers) are termed sensitive tint or first-order red plates. These quartz plates can be utilized to determine the sign of birefringence exhibited by the specimen. Use this Java tutorial to explore changes in specimen birefringence with a retardation plate when the polarizer is rotated.
Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.
Matthew J. Parry-Hill and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.
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