In order to improve the image reconstruction quality of multispectral correlation imaging system under the condition of low illumination, this paper proposes a multispectral correlation imaging scheme based on laser active illumination. In this scheme, the phase modulated multispectral correlation imaging camera is used as the experimental platform, and the laser is used as the auxiliary light source to increase the reflected signal intensity of the target object, and the image information of the target object is obtained through single exposure. The experimental results show that compared with the reconstruction results of multispectral association imaging under the condition of low illumination, the active and passive combination scheme can significantly improve the image reconstruction quality of the multispectral association imaging system. This paper is of great significance to promote the practical application of new multispectral imaging technology.
The Walsh function system has orthogonal completeness and is widely used in signal processing, image processing and communication. In this paper, three kinds of Walsh matrices, Hadamard order, Walsh- Like order and Paley order, are derived by Kronecker product based on row and block replication techniques of Walsh matrix, and the structural characteristics of different matrices are compared and analyzed. The generated Walsh matrix is used as the measurement matrix to modulate the optical field of the computed ghost imaging system. The simple binary object and the complex gray object are used as the target object, and the secondorder correlation operation is used to reconstruct the target object. The numerical simulation results show that the three matrices can reconstruct the target object with high quality under full sampling conditions, but the reconstructed image quality of Paley-ordered Walsh matrix is much better than Hadamard order and Walsh- Like order under low sampling conditions, which can effectively reduce the data sampling rate and improve the signal-to-noise ratio of ghost imaging system.