This Small Business Innovation Research Phase I proposal aims to develop a polariscope employing a tunable diode laser as light source, which can measure optical retardations in a wide range. Dynamic wavelength modulation will be used to measure very small retardations and static wavelength modulation will be used to measure large retardations. The principle developed will be applicable not only for birefringence measurement, but also in many other fields of optical metrology. Birefringence measurement is a challenging problem in glass, polymer and ceramic industries. Residual birefringence in these materials is introduced during the manufacturing process. Birefringence is related to one or more of physical variables such as internal stress, molecular orientation, crystal arrangement, etc. During the manufacturing process, residual birefringence is used as one of the quality control criteria. The technique of photo-elasticity is generally employed to measure birefringence in transparent materials. In photo-elasticity, birefringence is computed by measuring the retardation between two polarized light waves passing through the material. The measurement process is not too involved when the retardation is farther from zero and smaller than one wavelength. However, the measurement problem gets complicated when the retardation approaches zero or when it is more than one wavelength. There is no commercial polariscope that can solve these two problems simultaneously. The proposed instrument will be a highly beneficial tool for measuring birefringence in glass, plastic and ceramic products. The polariscope can be used as a process/quality control device in various glass, plastic and ceramic industries. Specific customers will include: manufacturers of high quality glass, optical fibers, ceramic crystals, plastic films/sheets, compact disk, consumer electronics industry, automotive and aircraft glass and plastic industry.
