Frequency modulation in the optical alignment of wavelength-converted laser sources

A laser projection system comprising at least one semiconductor laser, a wavelength conversion device, one or more adjustable optical components configured to optically couple the output of the semiconductor laser with an input face of the wavelength conversion device, an intensity sensor configured to monitor the intensity of a wavelength-converted output λCONV of the wavelength conversion device, and a laser controller programmed to operate the semiconductor laser wherein the controller is programmed such that at least the following conditions apply to the operation of the semiconductor laser:

• upon initiation of a set-up operation, the semiconductor laser generates a wavelength-modulated output beam λMOD that is modulated over a range of wavelengths encompassing a substantial portion of a FWHM conversion efficiency bandwidth of the wavelength conversion device;
• the modulated output beam λMOD is directed towards the input face of the wavelength conversion device;
• the adjustable optical components are operated to vary the position of the modulated output beam λMOD on the input face of the wavelength conversion device;
• the intensity of a wavelength-converted output λCONV of the wavelength conversion device is monitored by the intensity sensor as the output beam of the laser is modulated and as the position of the modulated output beam λMOD on the input face of the wavelength conversion device is varied;
• a maximum value of the monitored intensity of the wavelength-converted output λCONV is correlated with optimum coordinates representing the position of the modulated output beam λMOD on the input face of the wavelength conversion device;
• the variation of the position of the modulated output beam λMOD on the input face of the wavelength conversion device is terminated, at least temporarily terminating the set-up operation;
• and
• operation in a data projection mode is initiated by directing an intensity-modulated laser beam from the semiconductor laser to the wavelength conversion device using the optimum positional coordinates for the adjustable optical components.