text: Spectroscopic photo-reflectance employs a broad band probe light source, which may cover wavelengths from the infrared to the ultraviolet. By fitting spectroscopic photo-reflectance data with the conventional third derivative functional form, a comprehensive set of interband transition energies, amplitudes, and widths may be obtained, providing an essentially complete characterization of the electronic properties of the sample of interest. However, owing to the need to keep the probe light intensity to a minimum and to the practical necessity of phase-locked detection, spectroscopic photo-reflectance measurements must be made sequentially, i.e. probe one wavelength at a time.  
  This constraint limits the speed of spectroscopic photo-reflectance measurements, and coupled with the need for a careful fit procedure, renders spectroscopic photo-reflectance more suitable for analytical applications. Conversely, laser photo-reflectance employs a monochromatic light source, and hence is well suited for industrial applications. Moreover, in commonly encountered situations, the coherent wavefront of laser probe beam may be used to isolate the refractive component of the photo-reflectance signal, greatly simplifying the data analysis.