Virtual image distance (VID) is a key parameter in augmented reality (AR) or virtual reality (VR) systems and has a great influence on product performance and user experience. Therefore, it is very necessary to measure the VID accurately and efficiently. In this paper, we develop a VID measurement system which needs no mechanical scanning in the measurement process. The VID can be measured in a short period of time based on one single image generated by the AR/VR system. An image-telecentric lens is designed which is used to capture the virtual image. A diaphragm with two pinholes is placed at the entrance pupil plane of the imaging lens. When the imaging lens is not focused on the virtual image, the captured image contains two copies of the virtual image with a certain interval which is proportional to the VID in units of diopters. By calculating the interval, we can obtain the VID. A simulation is performed in LightTools to verify the effectiveness of the measurement system, and the result indicates that the measurement error is 5 mm when the virtual image is at 3 m.
Ultra-throw projector has been widely used in the projection application of large-FOV and short projection distance. However, the projection imaging distortion problem cannot be neglected due to the uncertain factor, such as the unsmooth factor of projection surface. In this paper, we proposed the image predistortion method based on radial basis function (RBF) image warping method to correct the projection distortion due to the unsmooth or wrinkled projection surface. The RBF image predistortion method and chief ray tracing method are used to realize a high-precision image predistortion. In addition, the distortion effect caused by the wrinkled projection surface with different depths are simulated. The distortion correction effects are also verified to less than 1% by the ray-tracing simulations.
The compound eye optical system has attracted much recent attention, owing to its large field-of-view, compact structure, and rapid imaging capabilities. We designed a compact image scanner (cross-section 36.5 mm × 17 mm) based on the compound eye system. A single imaging unit is mainly composed of two freeform mirrors and a flat mirror, and its field-of-view in object space reaches 10 mm. The modulation transfer function of the system is greater than 0.6 at 12 cycles/mm corresponding to Nyquist spatial frequency of 600 dots per inch in depth-of-field of 0~4 mm. Furthermore, a larger field-of-view is achieved by splicing multiple imaging units with 1-mm overlap in object space. An object-side telecentric system is used to obtain constant magnification at different object distances and the distortion (<1 μm) is controlled by freeform mirrors. The final image is obtained by image splicing. The imaging quality of the scanner is further improved by eliminating stray light.
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.