Research On Lateral Resolution Detection Method And Device Of Ophthalmic OCT Equipment Based On Beam Numerical Aperture

Optical coherence tomography(OCT)is a new type of medical tomography technology,based on Michelson interferometer,which is widely used in the field of ophthalmology diagnosis.At present,OCT equipment are gradually being promoted,but the related OCT measurement standards have not been released yet.Lateral resolution is one of the main indexes of ophthalmic OCT equipment measurement,and its accuracy is crucial to imaging quality of ophthalmic OCT equipment.The lateral resolution detection method based on beam numerical aperture takes advantage of the inherent characteristics of the ophthalmic OCT equipment,which has high stability and convenience.However,the lateral resolution detection method based on beam numerical aperture is easily affected by interference fringe and noise,resulting in lower precision in lateral resolution detection.Therefore,studying ophthalmic OCT equipment lateral resolution detection method and improving detection accuracy,has important reference significance in quality control and standard setting.In this paper,based on the imaging principle of the ophthalmic OCT equipment and the focusing characteristics of the near axis Gaussian beam,the lateral resolution calculation method is analyzed.In view of the influence of interference fringe and noise to lateral resolution detection,a light intensity distribution model is constructed to describe the width of the beam in the direction of beam propagation,which is based on light intensity distribution characteristic of the ophthalmic OCT equipment.In order to improve precision and speed of parameter identification,a lateral resolution detection method based on edge fitting and dynamic weight particle swarm optimization algorithm is proposed.Before determining DWPSO algorithm optimization space,a circle fitting algorithm is used.A dynamic weight factor is proposed to update particle’s velocity,then using DWPSO algorithm to identify beam width of light intensity distribution model,and it is used to obtain divergence angle and beam numerical aperture by least square fitting.Finally,ophthalmic OCT equipment’s lateral resolution can be calculated by beam numerical aperture.Based on the virtual instrument technology,a lateral resolution detection device for the ophthalmic OCT equipment is developed,and the accurate measurement of beam numerical aperture and lateral resolution are realized.The experimental shows that the proposed method of lateral resolution detection based on edge fitting and dynamic weight particle swarm optimization for OCT equipment can effectively avoid the influence of interference fringe and noise.It also has high accuracy result for ophthalmic OCT equipment lateral resolution detection.The lateral resolution detection device of ophthalmic OCT equipment based on virtual instrument technology is developed,which realizes the detection of commercial ophthalmic OCT equipment.