Two practical methods for improving the long-term stability of the photoelastic optical fiber pressure sensor

The differential approach of photoelastic optical fiber pressure sensor (POFPS) has been published. However, the experimental aspects of this sensor were little involved in it. Two practical methods are described to investigate this subject. First, the discordance of expansion coefficient, between the cladding steel and the graded-index (GRIN) lens, is considered by using indium steel cladding instead of the conventional stainless steel cladding. Then an experimental setup is designed to make the infrared light intensity distribution observable by using a CCD camera. Practical tests prove that these two practical methods and the design of the differential approach have improved the long-term stability of POFPS.