Visualization of two-dimensional phase gradients by subtraction of a reference periodic pattern.
Visualization of two-dimensional phase gradients by subtraction of a reference periodic pattern.
We describe a simple method for visualization of phase objects. The phase object is placed between a printed two-dimensional periodic pattern and a CCD camera. The ray deflection that is due to the phase object distorts the image of the pattern. This image is subtracted from a reference image and then, by squaring and low-pass filtering, a measurement of the two-dimensional refractive-index changes is obtained. Because the optical system does not require special alignment or illumination, the method presented has potential application for detection of gas leaks in industrial environments.
Perciante CD, Ferrari JA.