Pixel Super-Resolution Interference Pattern Sensing Via the Aliasing Effect for Laser Frequency Metrology

The superposition of several optical beams with large mutual angles results in sub-micrometer periodic patterns with a complex intensity, phase, and polarization structure. For high-resolution imaging thereof, one often employs optical super-resolution methods such as scanning nano-particle imaging. Here, it is reported that by using a conventional arrayed image sensor in combination with 2D Fourier analysis, the periodicities of light fields much smaller than the pixel size can be resolved in a simple and compact setup, with a resolution far beyond the Nyquist limit set by the pixel size. The ability to resolve periodicities with spatial frequencies of & AP;3 & mu;m(-1), 15 times higher than the pixel sampling frequency of 0.188 & mu;m(-1), is demonstrated. This is possible by analyzing high-quality Fourier aliases in the first Brillouin zone. In order to obtain the absolute spatial frequencies of the interference patterns, simple rotation of the image sensor is sufficient, which modulates the effective pixel size and allows determination of the original Brillouin zone. Based on this method, wavelength sensing with a resolving power beyond 100,000 without any special equipment is demonstrated.