Research On Vacuum Detection Of Vacuum Glass By Digital Holography

Vacuum glass is an energy-saving and environmentally friendly product with excellent performance.It uses a vacuum chamber to achieve functions such as heat insulation,sound insulation,and antifog.It is widely used in construction,transportation,photovoltaics,and other fields.Accurate detection of the vacuum degree inside the vacuum glass is an important means to ensure its quality and performance.At present,due to the special structure of vacuum glass,quantitative nondestructive testing of its vacuum degree is a research hotspot.Digital holography(DH)technology is a non-contact,non-destructive,high-precision,real-time detection technology,which has broad applications in micro-deformation detection,three-dimensional shape measurement and stress field analysis.In this paper,an optical pressure sensor is designed.The sensor is sealed with a substrate and a pressure-sensitive diaphragm to form a tiny cavity.Through the finite element software,the deformation and stress of circular,rectangular and square pressure-sensitive diaphragms under the same pressure load were compared and analyzed,and the circular single-crystal silicon diaphragm with high sensitivity,stable chemical properties and uniform stress distribution was selected as a pressure sensitive diaphragm.The sensor is placed in the glass cavity,and the digital hologram of the pressure-sensitive diaphragm under different vacuum degrees is recorded by CCD.The FIMG4 FFT algorithm is used to reconstruct the phase value of the digital hologram of the pressure-sensitive diaphragm under different vacuum degrees.The Window Transform Fourier(WTF)suppresses the scattered noise in the phase,and the phase distribution is obtained by the iterative least square method,and the deformation of the pressure-sensitive diaphragm is obtained according to the phase distribution.Based on the mapping relationship between the deformation of the pressure-sensitive diaphragm and the change of the vacuum degree,the quantitative non-destructive detection of the vacuum degree of the vacuum glass is realized.Using digital holography technology,the detection system measured the deformation of two different sensitivity pressure-sensitive membranes under different vacuum degrees,and established their corresponding relationship with vacuum degree,The fitting relationship is basically consistent with the theoretical value,and the relative average deviations are 2.43% and 6.25% respectively.Under different initial vacuum degrees and detection ranges,the different attenuation of the vacuum degree of vacuum glass is measured according to the fitting relationship.The measurement results are in good agreement with the measurement of the high-precision electronic differential pressure meter,and the maximum measurement error is 50 Pa smaller.The test results show that the digital holographic detection system is accurate and stable,and has potential application prospects in the field of vacuum glass vacuum degree detection.