Reflectorless Laser Rangefinding System

Reflectorless laser rangefinding systems are capable of detecting reflections from many types of materials and at most angles of incidence. There are several laser rangefinders with build-in inclinometers and compasses. These devices are similar to a total station in that distance, azimuth and inclination for three dimensional positions can be resolved. The accuracy of these guns is typically 0.50 degrees in azimuth and 0.20 degrees in inclination and 10-20 centimeters in range. The 0.5 degree in azimuth accuracy is the major concern when using the compass, but it can be reduced to 0.1 degree with the "Bogen". The inclinometers are very stable but often have maximum zenith angles of 45 to 60 degrees. The compasses are effected by the usual magnetic interference. The gun can be hand held or stabilized on non-magnetic monopods or tripods. The data is recorded on PCMCIA cards and/or internal memory or directly input into hand held computer through our software, such as Hammerhead computer. A critical operational characteristic for digital geologic mapping is for the gun to be able to range in a continuous mode (1 to 3 Hz) so that the user can sweep it across the geology and "laser sketch" the features.

Total stations can be defined as survey instruments that include a laser rangefinder, and horizontal and vertical angle measuring capabilities, with angular measurement error in the 3 to 5 second or so range, resulting in 1-4 cm per kilometer accuracy. Several of these now have reflectorless capabilities by flipping a switch. The theoretical maximum range for the reflectorless total station is a lmost always 100 meters (i.e. they assume perfect flat, few like list a 250 meter maximum range with a 90% reflective vertical white surfaces) but for geological surfaces the ranges are commonly 20% less. A potential problem with the total stations is that the optics are so powerful that the field of view is very small.

GPS Equipment at UTD

Currently, we have two complete set of Laser Atlanta Rangefinding system (including laser gun and Bogen). One Topcon total station (with reflectorless capability) is on loan from EXI Inc.