Magnifier principle of camera projector

A convex lens is made according to the refraction principle of light.

A convex lens is a kind of lens with a thick central part. Convex lenses are divided into biconvex, plano-convex, concave-convex (or positive meniscus) and other forms. Thin convex lens is also called condenser because of its convergence, while thick convex lens has the effect of telescopic, divergent or convergent, which is related to the thickness of lens.

When parallel rays (such as sunlight) are parallel to the axis (the straight line connecting the spherical centers of the two convex lenses is called the main optical axis of the lens), the rays are refracted twice on both sides of the lens, and the point concentrated on the axis is called the focal point of the convex lens (denoted as F). A convex lens has a focal point on both sides of the mirror. If it is a thin lens, the distance between the two focal points and the center of the lens is approximately equal. The focal length of a convex lens refers to the distance from the focal point to the center of the lens, which is usually expressed by F. The smaller the spherical radius of the convex lens, the shorter the focal length. The convex lens can be used for magnifying glasses, glasses for presbyopia and hyperopia, cameras, film projectors, microscopes, telescopes, etc.

The experimental study on the imaging law of convex lens is as follows: when the object distance is within a focal length, an upright and enlarged virtual image is obtained; When the focal length is between 1-2 times, the inverted magnified real image is obtained; Beyond the double focal length, the real image is reversed and reduced.

This experiment is to study and confirm this law. In the experiment, there are the following tables:

The attribute of the object distance u image and the position of the image.

So as to enlarge or reduce the image distance v between the virtual image or the real image and the objects on the same side and the opposite side.

Inversion reduction of the reverse side of u & gt2f real image F

U=2f Inverts the opposite side of the large real image v=2f.

F<u< real image opposite to v> is inverted and enlarged; 2f

U = f- (meaningless, dislike)

U<f vertical magnification virtual image u ipsilateral v.

This book is a table designed to prove this rule. In fact, lens imaging satisfies the lens imaging formula:

1/u (object distance)+1/v (image distance) = 1/f (lens focal length)

The camera actually uses the imaging principle of convex lens. A convex lens, let the focal length be f (the convex lens can converge light, the point where the light converges is called the focal point, and the distance from the focal point to the center of the convex lens is the focal length), and the object distance (the distance from the object to the center of the convex lens) be u, then when u >; 2f. Put an opaque object on the other side of the convex lens, which is called a light screen in physics. On the light screen, you can get an image exactly like the real thing, but this image is inverted and reduced.

A simple visual optical device for observing the details of an object is a converging lens, whose focal length is much smaller than the apparent distance of the eye. The size of the object imaged on the human retina is directly proportional to the angle (viewing angle) from the object to the eye. The larger the viewing angle, the larger the image, and the more you can distinguish the details of the object. Moving closer to the object can increase the viewing angle, but it is limited by the focusing ability of the eyes. Use a magnifying glass, make it close to the eyes, and put the object in its focus to form an upright virtual image. The function of magnifying glass is to enlarge the angle of view.

The object will not be imaged in the focal point, but twice the focal length is the same.

The handstand is smaller than the second Jiao Da and the second coke.

When the object is in focus, a large virtual image is seen on the opposite side.

If an image can be displayed on the screen, it must be a real image.

1.u > f becomes a real image, u < f becomes a virtual image, and the focus is the dividing point between the real image and the virtual image.

2. When u > 2f, it becomes a reduced real image, and when u < 2f, it becomes an enlarged real image. The bifocal point is the dividing point between the enlarged real image and the reduced virtual image.

3. When a real image is formed, the object distance decreases, the image distance increases and the image becomes larger; As the object distance increases, the image distance decreases and the image becomes smaller.

4. When a real image is formed, the image and the object are on different sides of the convex lens, and when a virtual image is formed, the image and the object are on the same side of the convex lens.

5. The real image is the convergence of actual light, which can be displayed on the screen, and the virtual image is the intersection of the reverse extension lines of refracted light, which is not displayed on the screen.