waveguide which leads to a pointing instability of the output laser beam referring again to fig1 gain chip 11 has a broad gain bandwidth to support a large number of laser cavity modes that span a relatively large range of wavelengths gain chip 11 is driven by driver 42 that can be an electric current pulsed source light from the front facet 13 of gain chip 11 is diffracted from a diffraction grating 16 the angle of diffraction grating 16 relative to the light beam from gain chip 11 is chosen to select a particular laser cavity mode to lase the angle is set by an actuator 15 that rotates the grating around an axis 23 that is chosen such that the wavelength of diffracted light that returns to gain chip 11 and the length of the cavity are maintained to provide the desired laser wavelength lens 17 collimates the output beam to the desired size to provide the output light that is used by the measurement system that utilizes laser 10 as its light source lens 22 collimates the light leaving front facet 13 of gain chip 11 to a diameter that is set to provide the desired wavelength resolution from diffraction grating 16 increasing the number of grooves covered by the laser beam on diffraction grating 16 provides narrower wavelength bands in the diffracted light that reaches gain chip 11 one method to achieve this desired narrow.