An apparatus comprises: a microscope objective focused on a microscope field of view; a light source including a laser generating an astigmatic beam and optics configured to couple the astigmatic beam into the microscope objective to produce high aspect ratio illumination at the microscope field of view; and a data acquisition system configured to generate data pertaining to light emanating from the microscope field of view responsive to the high aspect ratio illumination. The apparatus may be a Raman spectroscopy system. The laser may be an edge emitting laser. The optics of the light source may include an aspherical lens arranged to compensate the astigmatism of the astigmatic beam. The optics of the light source may include a diffraction grating arranged respective to the laser to provide feedback reducing a spectral full width at half maximum (FWHM) of the astigmatic beam.