An optical lens is used for a glass or plastic component on the light source that can change the direction of light or control the distribution of light.

　　 Optical lens is the most basic optical element that composes the microscope optical system. The objective lens, eyepiece and condenser are all composed of single and multiple lenses . According to the difference of its shape, it can be divided into two categories: convex lens (positive lens) and concave lens (negative lens).

　　 When a beam of light parallel to the main optical axis passes through the convex lens and intersects at a point, this point is called the 'focusflat'. There are two focal points. The focal point in the object space is called the 'object focal pointThe focal plane at the position is called the 'image square focal plane'.

　　After the light passes through the concave lens, it becomes an erect virtual image, while the convex lens becomes an inverted real image. The real image can be displayed on the screen, but the virtual image cannot

　　>The core summary of the principle of optical lens imaging: 1. The optical lens is represented by the lens symbol (a line segment has two V Shape mark), draw the main optical axis, mark the optical center and focus to reflect the two refracted rays of the three special rays of the lens (一

　　 1. Lens for lens Symbol to indicate (a line segment has two V-shaped signs at both ends), draw the main optical axis, mark the optical center and focus.

　　 According to the three special rays of the lens At the intersection of two refracted rays (generally the rays passing through the optical center and the rays parallel to the main optical axis are better), the characteristics of the image formed by the lens (such as virtual reality, size, front and back, etc.) can be obtained.

　　2. When the lens is imaging, all the light shining on the lens from each point on the object is imaged in the same position, blocking a part, and does not affect the other rays of the lens Image, so you can still see the complete image, but because the light hitting the image is reduced, the brightness of the image on the screen will become darker.

　　3. Convex lens imaging Rule:

　　(1) A condition that the convex lens needs to be met to form a real image is (u>f).

　　(2 ) Conjugate imaging means that the size of the object distance and the image distance can be interchanged. In the two cases, it becomes an enlarged and reduced inverted real image.

　　 4. Through a convex lens Looking at a clock outside of the double focal length, the image of the second hand still rotates clockwise, because it is an inverted real image at this time, and it is still the normal direction when viewed backwards, so it still rotates clockwise