ABSTRACT
We present a new approach to coherent averaging in digital holography using singular value decomposition (SVD). Digital holography enables the extraction of phase information from intensity measurements. For this reason, SVD can be used to statistically determine the orthogonal vectors that align the complex-valued measurements from multiple frames and group common modes accounting for constant phase shift terms. The SVD approach enables the separation of multiple signals, which can be applied to remove undesired artifacts such as scatter in retrieved images. The advantages of the SVD approach are demonstrated here in experiments through fog-degraded holograms with spatially incoherent and coherent scatter.
ABSTRACT
A new coherent polarization beam combination (CPBC) architecture was employed to combine four amplified beams and produce over 25 W of coherent output with 94% efficiency and nearly diffraction-limited beam quality. The individual beams were produced by a fiber master oscillator power amplifier system and their phases were controlled and locked using servo-controlled phase modulators. The CPBC approach relies on a coherent superposition of orthogonal polarization states and allows the combination of an arbitrary number of beams with arbitrary power ratios.
ABSTRACT
Four actively phase-locked beams produced by fiber amplifiers in a master oscillator power amplifier (MOPA) configuration were coherently combined in a glass capillary re-imaging waveguide producing more than 100 W of coherent output with 80% combining efficiency and excellent beam quality. The beam combiner components maintained a temperature below 30 degrees C with no external cooling at >100 W of combined power.
