The fast improvement of laser scanning technology has pushed terrestrial laser scanning (TLS) to the forefront of geodetic deformation analysis. As TLS becomes more integrated into this field, it is critical to construct a stochastic model that appropriately describes the uncertainty in TLS measurements. This includes creating a valid and fully populated variance-covariance matrix (VCM) for TLS polar observations. This approach requires estimating variances for range, vertical, and horizontal angles, as well as determining the correlations between these observations. In this contribution, we present an efficient strategy to determine the range variances in TLS based on raw intensities. A two-dimensional measuring approach is used on various specimens with TLS devices that offer raw intensity measurements, such as the Z+F Imager 5016A series. Verification is carried out using the observations from real-world scenarios (Brucher Water Dam and Bonn reference wall). Overall, this work proposes a methodology for evaluating the range variations of the specified TLS device.