Proceedings Article | 4 November 2003
KEYWORDS: Liquid crystals, Phase shifts, Interferometers, Microfluidics, Optical spheres, Diagnostics, Glasses, Fabrication, Dichroic materials, Polymethylmethacrylate
Conventional phase-shifting interferometers are extremely sensitive to mechanical shock and transmitted vibration because they utilize separate test and reference optical paths that must be aligned to within a fraction of the wavelength of the light being used. Such interferometers are difficult and time consuming to set up, align, and maintain, and are costly due to the number of optics required for the dual-path design. Common-path interferometers such as the point-diffraction type are much less sensitive to environmental disturbances but until recently have not been capable of phase-shifting. The liquid crystal point diffraction interferometer (LCPDI), first demonstrated by Mercer and Creath, employs a dye-doped, electro-optical LC device as the point-diffraction source to lend phase-shifting capability to the PDI common-path design. The advantage of this approach is that it combines the strengths of both types of interferometer to produce a phase-shifting diagnostic device that is much more compact, robust, and accurate than dual-path interferometers while at the same time using fewer optical elements. Such attributes make this device of special interest for diagnostic applications in the scientific, commercial, military, and industrial sectors where vibration insensitivity, power requirements, size, weight, and cost are critical issues. In this paper, we will describe some recent activities in the areas of materials development, device design, and fabrication techniques for the original LCPDI to improve its accuracy, extend its operation to both the visible and near-IR regions of the spectrum, and to improve its temporal data collection capabilities to near video frame rates.
