Multi-point differential laser doppler velocimeter using arrayed waveguide gratings with small wavelength sensitivity.

A multi-point laser Doppler velocimeter (LDV) using the arrayed waveguide gratings (AWGs) with small wavelength sensitivity (less than 1/10 of that for a conventional LDV without the AWGs) is proposed, in which velocities at different points in the depth direction can be simultaneously measured with compact optical systems. The design and characteristics of the proposed LDV are investigated with the model using the grating equation of the AWGs. From our simulation results, the wavelength sensitivity for multiple measured points can be reduced to less than 1/10 of that for a conventional LDV without an AWG.