In response to the issues of visual occlusion in single-camera fringe projection, which makes it difficult to achieve three-dimensional panoramic object shape reconstruction and complicates system calibration in multi-camera fringe projection, a new method is proposed that uses a dual-plane mirror to assist single-camera fringe projection for three-dimensional panoramic object shape reconstruction. This method is based on a coordinate transformation approach using camera-projector calibration, which utilizes the dual-plane mirror to transform from the real camera coordinate system to the virtual camera coordinate system, thereby achieving the transformation from a virtual point cloud to a real point cloud. The method is simple and easy to implement and does not require initial estimation of the initial parameters of the plane mirror, which will greatly reduce the 3D reconstruction error and improve the computational speed. Finally, experiments on stepped standard workpieces and complex-shaped objects are conducted for three-dimensional reconstruction. The experimental results show that compared with the standard gauge block, the measured average absolute error and relative error are 0.0815 mm and 0.6738685%, respectively. This method not only effectively solves the problem of visual occlusion in fringe projection but also partially addresses the issue of information loss in object reconstruction due to high surface reflectivity, providing new insights for solving the problem of high surface reflectivity on objects.
Images can convey information and needs to be protected, which is usually done by encryption. Traditional image encryption methods usually use software or hardware encryption, which has improvement approach in terms of better safety and robustness. And the study arouses sympathy to researchers based on both software and hardware encryption. This paper proposes an encryption method that combines software algorithm encryption and hardware encryption using a spatial light modulation (SLM) and 4f optical system. Firstly, the image is chaotically encrypted using the chaos encryption algorithm. Secondly, the discrete cosine transform (DCT) is adopted for further encryption based on chaos encryption picture. Thirdly, the cipher text image is transformed into the 4f system using SLM, which performs a random amplitude on the image to achieve hardware encryption. Finally, the simulation and experiment are performed to verify that the scheme, which shows that the method can realize the encryption and unencryption under the combination of software and hardware encryption. The proposed method has application value to guarantee the higher security of information.
In the traditional microfield speckle pattern interference measurement system, due to the use of high-magnification objective lens, the working distance is small and the shearing device cannot be introduced to implement shearography measurement. Thus the distribution of the deformation gradient on a microstructure surface cannot be measured. A system for the synchronous measurement of the surface deformation and gradient distribution of a microstructure was designed. Through the combination of focusing lens, convex lens, and low-magnification objective lens, the microstructure surface was clearly magnified and the internal distance of the system was enlarged. Thus the shearing device can be introduced to realize the shearography measurement under the microfield view. The synchronous full-field measurement of the structural surface deformation and its gradient distribution was further realized by the introduction of a reference light and designing of an optical path switch. In addition, the designed system had a zoom feature, which can facilitate the measurement in variable field of view in a certain range. The feasibility of the system was verified by theoretical analysis and experiment, and the practicability was validated by testing the chip and circuit board.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.