Characteristics and classification of industrial lenses

Optical lens is commonly called camera lens or photographic lens, short for lens, its function is optical imaging. Lens is an important component of machine vision system, which plays a key role in imaging quality. It has an impact on several main indicators of imaging quality, including resolution, contrast, depth of field and various aberrations. Lenses not only have many kinds, but also have great quality differences. However, ordinary users often pay insufficient attention to the selection of lenses when designing the system, which leads to the failure of obtaining ideal images and even the failure of system development.

The industrial lens is equivalent to the lens of the human eye. Without the lens, the human eye cannot see anything. If there is no lens, then the output image of the camera; It's a white field with no clear image output, which is consistent with the principle of camcorders and cameras at home. When the muscles of the human eye fail to stretch the lens into its normal position, known as myopia, the scene becomes blurred. The coordination of camera and lens also has a similar phenomenon. When the image becomes unclear, the back focus of the camera can be adjusted, and the distance between the CCD chip and the industrial lens datum can be changed (equivalent to adjusting the position of the human lens) to make the blurred image clear. Thus, the lens in the closed circuit surveillance system is very important. Both engineers and builders work with lenses on a regular basis: designers calculate the focal length of the lens based on object distance and image size, and builders often make field adjustments, part of which is to adjust the lens to its best condition.

1, industrial lens installation size, interface

All camera lenses are threaded mouth, CCD camera lens installation has two industrial standards, namely C mounting seat and CS mounting seat. Both have the same thread part, but the distance from the lens to the sensitive surface is different.

C Mounting base: The distance from the lens mounting datum to the focus is 17.526mm.

C/S mounting seat: Special C installation, in this case, the front washer of the camera should be removed before installing the lens. The distance from the lens mounting datum to the focal point is 12.5mm. If a C mount lens is to be mounted to a C S mount camera, a 5mm thick socket is required.

Classification and characteristics of civil lens

Lenses are generally classified according to their focal length:

Fisheye lens; Macro lens; Wide Angle lens; Standard lens; Telephoto lens; Ultra telephoto lens; Zoom lens, etc.;

Standard lens: can shoot scenery and people, between wide Angle and telephoto;

Telephoto lens: take close-up of distant figures and distant objects, such as sports games;

Wide-angle lens: shooting scenery and large scenes with infinite focal length;

Fisheye lens: Angle of view 180 degrees, large distortion, special use;

Macro lens: shoot small objects at close range, such as small ants, etc.

Super telephoto lens: can shoot the moon and stars;

Zoom lens: A lens whose focal length can be changed according to the object being photographed, which can produce motion.

The difference between industrial lens and civil lens

1, different clarity

Lens resolution is highest in the center of the image surface, with a difference at the edges. The center resolution of the ordinary lens can basically meet the definition, while the definition of the edge is much reduced, the overall resolution can meet the requirements of the ordinary camera 440,000 pixels. There are three key factors that determine lens sharpness:

(1) Lens material and purity. The less impurities in the lens, the less interference light it produces, and the clearer the picture is.

(2) the grinding accuracy of the lens. The grinding precision of the lens is determined by the grinding equipment. At present, the difference between the domestic lens and the foreign lens is only a few.

(3) Coating accuracy of the lens. Precise control of the coating process is also one of the determinants of lens clarity. In addition, the megapixel lens adopts the aspheric lens, which can reduce the aberration and improve the definition compared with the ordinary lens at the same time achieve the miniaturized design; Through the special optical design technology, from the image center to the surrounding part of the picture quality to achieve high resolution force, high contrast picture, compared with the traditional lens to improve the resolution force of about 2.5 times, even in the image cutting or magnification function, still can ensure high picture quality.

2, the spectrum transmission ability is different

The spectral transmission of the lens also contributes to the sharpness of the picture. The transmission of light with wide frequency will greatly increase the amount of light received by the camera target surface. It can enhance the contrast and brightness of the picture and enrich the details of the picture.

3, spectrum correction ability is different

The transmission capability of a wide spectrum is not sufficient for high precision imaging. When the spectrum correction ability of the lens is insufficient, some wavelengths of light can not be correctly imitated on the target surface of the camera, resulting in virtual image. It's a technique that ordinary lenses can't be coated with.