High speed three-dimensional laser sensor

Previous developments of Biris technology for road inspection applications led to the birth of a very rugged high power three-dimensional sensor using a three-line laser projector. In this hostile environment where shock, vibration, dust and dirt are constantly present, three-dimensional ranging must comply with very severe demands. Resolution, precision and reliability are strictly observed. The new approach keeps the same data density but uses high frame rate image capture and feature extraction. With high speed capture, the number of actual laser projections can be reduced to one, without having to decrease the number of measured profiles per second. This eases the data processing by keeping the same characteristics for the projected line from one acquired profile to the next and over the whole acquisition sequence. The data rate achieved maintains the maximum 10cm (4 inch) profile spacing for the road surface sampling up to speeds of 72km/h. Range measurements (z-vertical, x-lateral) and intensity I, are obtained for each measured point. The field-of-view and depth of field for this sensor are very important characteristics which are adapted for the application. However this solution implies a new sensor design and an optimized image capture geometry. Triangulation and defocusing are used to improve the signal to noise ratio and to provide immunity to false measurements.