Multifunctional Scanner Based On Lensless Single-pixel Imaging

Single-pixel imaging is a novel imaging technology,which uses spatial light modulators to encode two-dimensional or even three-dimensional spatial information of the target object,only one single-pixel detector is used as a signal acquisition device to acquire a series of modulated optical signals,and the spatial information of the target object can be reconstructed using a reconstruction algorithm.Compared to traditional imaging methods,the unique way of single-pixel imaging makes it great advantageous in some special applications.In this thesis,firstly,the lensless single-pixel imaging technology is studied.In the existing single-pixel imaging device,an optical system such as a lens is used to project structured light generated by a spatial light modulator onto a target object,and then the lens is used to concentrate the reflected or transmitted light of the object onto the single-pixel detector.The use of the lens makes the imaging device less compact and portable.In order to reduce the volume of single-pixel imaging device and make it compact and portable,a lensless single-pixel imaging scanner with a thickness of only 2.48 mm was designed by using liquid crystal display as spatial light modulator and large area flexible thin film solar cells as single-pixel detectors.According to the design and construction of lensless single-pixel imaging scanner,the application research of various functions has been carried out by simulation and experimental verification.The application of gray-scale scanning,full-color scanning,character recognition scanning and real-time encrypted scanning of lensless single-pixel imaging scanner has been realized.In the aspect of gray scale scanning,by using the transmission imaging characteristics of the scanner designed in this thesis,the function of scanning banknote watermarking that traditional scanners can not achieve is realized;the linear color correction algorithm is embedded in the full-color scanning function to achieve a high quality color scanning effect;realizes the character reco gnition function of scanning results of text documents on different font types,different font size and different thickness papers;according to the specific rules,the pixel order of the Hadamard base pattern is replaced,and the real-time encryption of the document scanning process is realized,which can improve the confidentiality of the encryption scan while ensuring the scanning quality and efficiency.Compared with the traditional scanners,the lensless single-pixel imaging scanner designed in this thesis has no optical lens components and mechanical scanning components.The scanning process is noiseless,light,compact and portable.It can scan important information such as banknote watermarking and paper texture by using the transmission imaging characteristics.Lenseless single-pixel imaging scanner makes up for the shortcomings of traditional scanners,such as relatively complex structure and mechanical scanning noise.Moreover,transmittance imaging and reflection imaging of traditional scanners complement each other,and can realize character recognition scanning and real-time encrypted scanning.It will have wide application prospects in many fields.