UniversitÈ Laval

Michel Piché

Yves De Koninck

Guy Rousseau

Patrick Langlois

A method and a system for obtaining a high-resolution image of a volume of a sample using laser imaging are provided. The method includes a step of probing the volume of the sample with a first excitation beam having an intensity profile of maximum intensity at a center thereof, thereby obtaining a positive image of the volume. The method also includes a step of probing the volume of the sample with a second excitation beam having an intensity profile of minimum intensity at a center thereof and defining a peripheral region of maximum intensity around the center, thereby obtaining a negative image of the volume. The method finally includes a step of subtracting the negative image from the positive image, thereby obtaining the high-resolution image of the volume of the sample. Advantageously, embodiments of the invention can be probe- and fluorescence-independent, and be conveniently retrofitted into existing laser imaging systems.

Method and system for improving resolution in laser imaging microscopy

There is described a method of characterizing a short laser pulse, the method comprising the steps of obtaining root-mean-square widths of the pulse through second order moments of the pulse; obtaining a spectral width of the pulse using the root-mean-square widths; obtaining a root-mean square temporal width of the pulse; and defining a Pulse Quality Factor proportional to a product of the spectral width and the temporal width. This approach does not require complete characterization of laser pulses and eliminates the need of any assumption to interpret autocorrelation traces. The method can be applied to pulses of arbitrary shape.

Method for characterization of laser pulses using pulse quality factor

Method of generating laser pulses using a semiconductor laser diode as a lasing amplification medium of an extended laser cavity are presented. Passive self-modulated mode-locked operation of the semiconductor laser diode is achieved by providing an above lasing threshold direct current input current to the semiconductor laser diode while the semiconductor laser diode is operational in a slightly misaligned extended laser cavity favoring the amplification of wavelengths shorter than a center wavelength of a continuous wave operational mode of the semiconductor laser diode at threshold.

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Cap-Rouge, Canada

Michel Piché