3D lens with scheimpflug intersection Analysis and Selection
3D lens with scheimpflug intersection Analysis and Selection
3D lens with scheimpflug intersection,as the name suggests, is a lens designed for imaging inclined surfaces
如图所示:
When the lens is not tilted, even with the smallest aperture setting, there will be some degree of defocusing in both the closest and farthest parts of the image. However, when the lens is tilted, and the lens plane, the shooting plane, and the image plane intersect at a single point, the entire image can be brought into sharp focus. Why does tilting the lens by a certain angle allow for the entire image to be captured clearly? We can provide a simple explanation, as shown in the following figure:
In optical imaging, the distance of the subject from the lens (object distance) varies, and consequently, the position of the image plane (image distance) also varies. Generally, the greater the object distance, the smaller the image distance, and vice versa. In the left image of the figure above, car A is further away from the lens, resulting in a closer image A' to the lens, which means a smaller image distance. Conversely, car B is closer to the lens, and its image B' is further from the lens, indicating a larger image distance. By moving the focusing plane forward or backward, only one point can be brought into sharp focus at a time. However, when the lens is tilted, the lens plane MN also rotates. At this point, the object distance for point A becomes AC, which is significantly reduced compared to when the lens was not tilted. Following the principle that a smaller object distance results in a larger image distance, the image point A' will then be further from the lens. Similarly, for object point B, the object distance increases after tilting, and so does the corresponding image distance. As the lens rotates, the object and image distances for points A and B continuously change, and at a certain moment, it is possible for both image points A' and B' to fall within the focal plane. In summary, after the lens is rotated, the object distance relative to the lens changes, and so does the image distance. When the lens plane, shooting plane, and camera plane all intersect at a single point, the entire subject can be imaged clearly. This condition, in optics, is known as Scheimpflug's rule.
Based on the ability to perfectly focus on a tilted plane, an important application of the 3D lens with scheimpflug intersection is its use in conjunction with structured light to achieve 3D surface reconstruction of objects. The testing principle is illustrated in the following figure. A projection device casts structured light (the striped lines in the figure) onto the surface of the object. As the object's surface is uneven, the structured light projected onto it also deforms and twists, which can be understood as the modulation of the structured light's optical field and phase by the object's surface, effectively carrying the surface contour information of the object. Subsequently, our 3D projection lens captures the modulated structured light clearly, and software algorithms are used to read the degree of curvature of the structured light, thus restoring the 3D surface topography of the object.
The 3D lens with scheimpflug intersection independently developed by DZOPTICS features a precision mechanical adjustment mechanism and an optical layout that complies with Scheimpflug's rule, enabling perfect focusing on a tilted plane.
Usage: Loosen the screws on both sides to allow the lens to rotate up and down, with a rotation angle of ±15°. Once a clear image of the tilted plane is achieved, tighten the screws on both sides.