Introduction to the imaging principle of the hotte

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Introduction to the principle of stereoscopic printing imaging

stereoscopic printing is based on the physiological characteristics of human eyes forming stereoscopic sense and the optical principle of grating plate refraction and image division. Through the use of grating plate, the planar two-dimensional image scenery has a stereoscopic sense. The following is a brief introduction to the imaging principle of stereo printing

1. The physiological characteristics of human eyes are that objects are in three-dimensional space, and the visual system can present the binary images formed by objects with different distances and depths on the visual membrane with a three-dimensional sense, which is called stereoscopic sense. Physiologically, there are many reasons for the formation of stereoscopic vision, including physiological and psychological. From the perspective of the imaging theory related to stereo printing, the physiological formation of stereo vision can be seen as two processes: first, the fixation point is determined by the spokes, and then the precise depth and position are determined by the binocular parallax

① convergence when both eyes gaze at an object at the same time, if the object is far away, the lines of sight of both eyes are basically parallel. When the object approaches, the two eyeballs rotate inward, and their lines of sight intersect at the object. This kind of movement of the eyes is called the lunge. Radiation has a direct effect on the formation of depth. The sense of depth caused by radiation is effective within 20m at a short distance, and its effect is significantly reduced at a long distance

② binocular parallax is shown in Figure 1. There is a certain distance (eye distance a) between the pupil of two eyes in the horizontal direction, and a certain included angle is formed between the pupil and the object when viewing the object, so the imaging of the object on the optic membrane of the left and right eyes is not exactly the same. This difference is called binocular parallax

when looking at the f-point, image at the optic membrane F and F of the left and right eyes respectively. The e point farther than f and the G point closer than f are imaged at e, e, G and g respectively. Obviously, the geometric positions of E, F, G in other areas of the optic membrane of the left and right eyes are different, so the different images obtained by the brain from the left and right eyes produce a depth. Generally, the convergence angle (convergence angle) is represented by,,, and the corresponding parallax angle is represented by (-) and (-)

the image formed by the object in the left and right eyes can be well fused into one within a certain parallax range, forming the information of depth and position

at this time, there is a sense of depth and stereoscopic vision. The range of binocular disparity perception depth is basically determined by the fusion range of two eye images, which is not very wide. However, binocular vision has high accuracy in resolving depth differences within the effective range

due to the combined effect of convergence and binocular parallax, the correct stereoscopic sense can be obtained in a wide range

③ allowable range of binocular parallax starting from the function and characteristics of binocular parallax, the image difference between the two eyes can be maintained within 5%-10%, as follows: (a) image size difference: the geometric figure is within 5%; when the difference is% it will cause eye fatigue;% Binocular parallax will be impaired when; Stereoscopic vision cannot be established when it is more than 5%

for general graphics, the difference can be maintained at%

(b) brightness difference: within 30% (c) chromaticity difference: 15nm (d) resolution difference: within 10% (up to 30% for images with low resolution). ④ lens regulation plays a certain role in the formation of stereoscopic vision in addition to radiation and binocular parallax. By changing the thickness of the lens, objects at different distances can be imaged on the optic membrane to obtain a certain sense of depth

but this distance is not very large, which is generally limited to meters

2. Imaging principle of cylindrical lens grating plate cylindrical lens grating plate is composed of many small cylindrical lens elements with exactly the same structural parameters and performance. One side is flat, and the other side is a surface with periodic fluctuations, as shown in Figure 3. In the direction perpendicular to the arrangement direction, the light does not converge; In its arrangement direction, each cylindrical lens element is equivalent to a convergent lens, which plays the role of focusing imaging. The plane of the cylindrical lens grating plate is the focal plane

this feature enables it to compress and isolate images

① geometric optical path analysis of cylindrical lens element zoom in and observe the cylindrical lens element composed of cylindrical lens grating plate. Because its thickness is greater than its radius of curvature, it cannot be ignored. Therefore, the main reason for optical analysis is that it is solid, easy to use and simply regarded as a thick lens, which belongs to the plano convex lens in the thick lens, as shown in Figure 4

thick lens can be treated as composed of two spherical refraction surfaces separated by a distance D (i.e. OO). After tedious algebraic calculus, the following set of formulas can be obtained: ⑴ among them, the object distance S0 and the image distance S1 are measured from the first main plane H1 and the second main plane H2 respectively, and the focal length f is also measured relative to the main plane H1. That is, S 0 refers to the distance from the object point to the first principal plane H1; S1 is the distance from the image point to the second principal plane H2; F is the distance from the focus to the first principal plane; H 1 is the distance from the first optical plane to the first principal plane (oh 1); H2 is the distance from the second optical plane to the second principal plane (oh 2); R 1 is the radius of curvature of the first optical surface; R 2 is the radius of curvature of the second optical surface

due to R 1, formula group ⑴ can be simplified and calculated as follows: ⑵ according to formula group ⑵, when the object distance S 0 and focal length f are known, the image distance S 1 can be calculated The focal length f is related to the refractive index n and radius of curvature R 2 of the lens

in stereoscopic printing, the grating plate is attached to the image, and the plane of the grating plate is the focal plane, that is, the image is located on the focal plane (FD). Because of this particularity, the cylindrical lens element that makes up the cylindrical lens grating plate has a special optical property - excellent electronic universal experimental motor on the image plane adopts any certain of the exchange servo speed regulation system to form a parallel beam after being refracted by the cylindrical lens

The light path diagram of the

cylindrical lens element is shown in Figure 5

point C in the figure is the node of the cylindrical lens, and the distance from the first optical plane to point C is Q. take the coordinate system o y, and the origin o is on the optical axis. For point Y0, a very thin beam parallel to the optical axis is formed after passing through the cylindrical mirror, carrying the corresponding information transmission, and its transmission direction angle is 0. For any Y-point, a very thin parallel beam is formed after passing through the cylindrical lens, carrying the corresponding information transmission, and the value of its transmission direction angle is. Because, we get: ⑶ and because, substituting into equation ⑶, we get: ⑷ from this, it can be seen that the light emitted at different positions on the o y plane is refracted by the lens into a very thin parallel beam, which will travel in different directions, and each beam carries its own information. Because the direction angle of the light beam formed by refraction at different points is different, the cylindrical lens plays the role of image division

from formula (4), we can know that the transmission direction angle of light is related to the radius of curvature R2, the refractive index n and the position of Y point. For a specific grating plate (i.e. R2 and N are known), we can calculate the direction of light transmission at a specific point, and we can analyze the microscopic optical path of the grating with plates outside the range that can be used because the price of carbon fiber is much higher

② imaging process of cylindrical lens grating plate cylindrical lens grating plate is a collection of many cylindrical lens elements. Its optical principle is the arrangement of micro unidirectional magnifiers, and its optical function is to compress and magnify the plane image in one direction. Therefore, the cylindrical lens grating plate can accommodate a large number of plane images and maintain the integrity of the plane image

will be compressed into a striped plane image, which will be arranged in the corresponding position on the focal plane of the lens in the order of left and right scenes. The cylindrical lens grating plate combines the image information carried by the very small light beam passing through each cylindrical lens element, and images respectively on the left and right eye membranes, forming the corresponding stereo image through the action of the central nervous system. Through binocular movement, the information carried by different beams is obtained, so as to obtain a three-dimensional spatial image with a very rich amount of information, as shown in Figure 6

3. The reasons for the formation of stereoscopic depth in stereoscopic printing are as mentioned above. The main reason for the formation of stereoscopic sense is the parallax of human eyes. When the brain synthesizes the image information obtained by the two eyes, one of the very important factors is the incident direction of the light of the object point. The orientation and distance of the object point can be determined according to the direction of the light emitted or reflected by each object point to the human eye

the light emitted from point E on plane m enters the left and right eyes respectively, and then the medium shot is formed

as mentioned above, as long as a set of left and right scene plane images of the scene can be recorded, and the left and right eyes can only see the corresponding parts of the corresponding left and right images, the eyes adjust the focusing angle due to the relative parallax between the left and right images, just like the state of simulating the real scene, producing a real three-dimensional feeling

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