Measurement of different types of optical loss using high-precision laser photometer

Abstract

The development of high-power laser systems requires optical components that function at peak performance. Here, a high-precision, double beam, 1064 nm laser photometer setup was developed to measure the following different forms of optical loss from Nd-glass samples: total loss, volume loss, and the residual reflection and surface loss. The double beam design and a lock-in technique were utilized to decrease the impact of light-source instabilities and signal noise, respectively. The stability of the signal was further improved by decreasing the amount of optical absorption along the light path and by increasing the detection responsivity. Paired samples were symmetrically placed to eliminate beam displacement, and a laser scattering imaging technique was used to determine the influence of surface defects on the optical performance. Using the above techniques, multiple measurements of the transmittance and reflection values of the sample were taken, which showed our transmittance measurement to be highly precise, exhibiting a relative standard deviation of less than 0.06%. Different types of optical loss were distinguished and obtained from the transmittance and reflection measurements of samples with different thicknesses. A comparison of the optical performance from test points with and without surface defects allowed us to determine the influence of surface defects on the optical performance.