Holographic Common-Path Interferometer for Angular Displacement Measurements with Spatial Phase Stepping and Extended Measurement Range

We report a new kind of compact and portable optical smoke sensor that uses an integrating cylinder as the light collector. Theoretical analysis shows that this smoke sensor can have high sensitivity and good linearity because a number of reflected lights participate in the measurement of smoke concentration. A smoke sensor has been constructed, and it has demonstrated improved sensitivity and linearity compared with the conventional direct-beam-based smoke sensor. Good agreement of theoretical and experimental results has been obtained. [Optical Society of America ]