Research On High Precision Ranging Technology Of Laser Triangulation Under Non-Scheimpflug Conditions

With the rapid development of modern industry,laser triangulation ranging system,as a non-contact ranging instrument with high precision,high efficiency and good robustness,is widely used in the field of photoelectric detection.At present,laser triangulation ranging has been mature in theory and has been verified and applied in various applications.Laser triangulation ranging requires accurate design of the imaging system to ensure that the laser spot can be focused at all times in the imaging system,that is,the imaging system meets the Scheimpflug condition.However,in practical application,meeting the Scheimpflug condition means that the optical lens and detector need non coaxial design,which has complex structure,higher cost and inconvenient use.Therefore,in practical application,the direct integration of imaging lens and camera coaxiality is generally adopted.This structure can significantly improve the stability and convenience of the system and greatly reduce the cost.However,due to this structure does not meet the Scheimpflug conditions,the ranging accuracy is low and the application field is limited.Based on the above background,this paper focuses on how to realize highprecision ranging by laser triangulation under non-Scheimpflug conditions.A series of innovative research results are as follows:Firstly,the theoretical model of laser triangulation spot position and ranging under non-Scheimpflug conditions is established.According to the model,the key reasons affecting the ranging accuracy of laser triangulation under non-Scheimpflug conditions are analyzed.It is concluded that accurately measuring the spot center position is the prerequisite for high-precision ranging under non-Scheimpflug conditions,which provides a theoretical basis for high-precision ranging of laser triangulation under non-Scheimpflug conditions.Then,the conical beam model is established,the positioning error between the theoretical center position and the centroid position after laser spot imaging is analyzed,the laser triangulation ranging error under non-Scheimpflug conditions is calculated according to the theoretical model of spot position and ranging,the ranging accuracy of different system parameters under non-Scheimpflug conditions is quantitatively evaluated,and the system parameter conditions suitable for large-scale and high-precision ranging under non-Scheimpflug conditions are given,And experimental verification.Under the condition of the shaped-center method measurement,the accuracy of RMSE method is 3.7 times higher than that of the traditional centroid method.Finally,the non-Scheimpflug condition high-precision large dynamic range laser triangulation ranging technology based on the diffraction grating splitting principle,combined with the error average effect,realizes the non-Scheimpflug condition laser triangulation high-precision ranging,and realizes the non-Scheimpflug condition laser triangulation large dynamic range measurement by successively measuring the highorder spots.The experimental results show that compared with the traditional laser triangulation method,the laser triangulation method based on diffraction grating improves the dynamic range by 56% while maintaining the ranging accuracy.To sum up,this paper focuses on the problem of low accuracy in laser triangulation ranging under non-Scheimpflug conditions.The shaped-center method is used to improve the spot positioning accuracy and the laser triangulation method based on diffraction grating is used to improve the measurement accuracy and measurement range.The correctness and feasibility of the method are confirmed by theoretical analysis,numerical simulation and experimental verification,which provides a possible and important reference for the development of high-precision ranging technology of laser triangulation under non-Scheimpflug conditions.