| Reliability testing is an important part of lens module processing and production,and only the lens module passing the reliability testing can be mass produced.After the reliability test,the relative position of the inner lens may change,which will affect the imaging performance of the lens module.Therefore,it is of great significance to quantitatively detect the change of relative position of lens module before and after reliability test.Most of the existing detection methods are based on the surface detection of lens,these methods can only detect one surface at a time,and the speed is slow.Optical coherence tomography(OCT)is a three-dimensional imaging technology with depth resolution.It has the advantages of non-invasive,high resolution and real-time imaging,so it has the development prospect of non-destructive testing before and after lens reliability.In this paper,based on optical coherence tomography,the nondestructive testing method of lens reliability is studiedA phase sensitive swept source OCT imaging system is designed and built.The axial resolution is 20μm,the measuring range is 11mm,and the line scanning speed is 100 kHz.It can realize the real-time OCT imaging of full lens in the lens module.By using the fiber Bragg grating(FBG)on the light source to calibrate the specific wavelength,and calculating the spectral shift through the phase error at the specific position,the phase correction of the swept source OCT system is carried out,and the phase stability of the frequency sweeping OCT system is realized.A multi lens displacement measurement method based on phase information is proposed,which breaks through the limitation of resolution of OCT system,including displacement measurement method based on depth domain phase,measurement range expansion method based on spectral domain phase,and phase correction method based on system self-referenced approach.The proposed method can simultaneously measure the displacement of multiple lenses,and the measurement accuracy can reach 0.1 μm. |
