Examples are given of a quick and convenient method of testing optical components: the parallelism of glass blocks; the 90° angle error and pyramidal error of a porroprism; and the error in the 45° angles of a right angle prism. A He-Ne laser source is used and the component to be tested acts as an interferometer.

Publisher Summary This chapter focuses on interferometry with lasers. The development of the laser made available for the first time an intense source of light with a remarkably high degree of spatial and temporal coherence. The use of lasers has removed most of the limitations of interferometers imposed by thermal sources and has led to the development of several new and interesting techniques in interferometry. Two other factors that have contributed to this revolution have been the progressive replacement of the human eye by photodetectors and the increasing use of sophisticated techniques of signal processing made possible by digital computers. These developments and the availability of tunable lasers, have led to new methods of measurement, some based on heterodyne techniques and others involving direct evaluation of the interference phase. Finally, interesting possibilities have been opened up by the use of single mode optical fibers and nonlinear crystals to build new types of interferometers with entirely new applications.

Interferometric method of checking parallelism and prism angles

III Interferometry with Lasers

During the operation of a high power pulsed CO2 laser system, damage was observed to a GaAs modulator crystal. The cause of the damage was possibly the creation of wedge fringes within the crystal. Wedge fringes were also formed in the system by a Ge polarizing plate. The authors describe how the formation of such fringes can be avoided and also how they can be used to measure small wedge angles over long path differences.

Interferometric method of checking parallelism and prism angles

Citations

III Interferometry with Lasers

Observation of wedge fringes on CO2 laser optical components

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