Laser Imaging Approach for Portable BTF Measurement System Automatic Alignment

The paper presents a new alignment sensing possibility for automation of BTF instrument with regards to the sample surface. We have developed a portable bidirectional texture function (BTF) measurement instrument allowing for on-site measurement outside the laboratory. It is a newly emerging technique enabling data acquisition of the real objects without the necessity of their extraction from the environment. A practical issue of the sample measurement is the instrument alignment against the measured surface. The system is provided with five degrees of freedom to be able to set the right position of the instrument to the sample surface without the necessity of the sample manipulation. We used a laser auto-collimation principle to provide feedback information for the system alignment. Now we propose a new approach for acquisition of the feedback information for the system alignment based on laser-imaging approach. We present theoretic relations of the proposed system and technical demands to reach the desired uncertainty of the system misalignment to the sample surface of less than 0.1°.