7 key points for industrial lens selection-telecentric optics to help you choose a lens

7 key points for industrial lens selection-telecentric optics to help you choose a lens

As one of the core components in the machine vision system, the industrial lens has a great correlation to the image acquisition. Telecentric Optical BTOS relies on years of industrial lens and telecentric lens industry experience to give the following selection process.

I. Analysis of customer needs (from the perspective of customers)

The sales technical engineer analyzes the lens demand scenario according to customer feedback, such as the working environment of the lens, whether other components (lenses, glass) are added between the lens and the object, etc., as appropriate as possible and different from person to person.

According to the customer's consultation situation, the following points can be basically obtained.

1. The customer's use of scene space needs to consider the hardware length and other parameters of the industrial lens

2. The whole system is running in a moving or relatively stationary scene

3.Special requirements for spectral response; for ultraviolet environment, ordinary glass lens will attract ultraviolet light

4. Price factor

5. Do you need to increase the light source (increasing brightness, local lighting, etc.)

6. The working environment of the industrial camera (temperature resistance, wet and dry, etc.)

7. Whether to add other devices

Do you need a telecentric lens?

Telecentric lenses are required for precision measurement systems. The main function of a telecentric lens is to overcome the effect of perspective phase difference (inconsistent magnification due to different distances during imaging), so that the size data obtained when the detection target moves within a certain range is almost unchanged. In general, telecentric lenses have a fixed focal length and working distance, and some telecentric lenses are large in size and some weigh more than ten pounds. You need to understand the customer ’s view of the field of view size, working distance, space restrictions, and The requirements of motion control can be determined after the required lens model specifications. When there is no strict requirement on the imaging of objects such as general surface defect detection and judgment, use a telecentric lens with less distortion.

Third, the depth of field of the machine vision lens

Some vision systems with special requirements require lenses with a relatively large depth of field. For example, in some inspections or measurements, an industrial camera must be angled and the entire object must be clearly imaged; the measured targets are not on the same plane, which requires the depth of field of the lens to be considered. The shorter the focal length, the greater the depth of field; the smaller the aperture, the greater the depth of field; the farther the lens is from the object, the greater the depth of field; the small aperture and good light make focusing easier, but the small aperture will lose the fine structure of the object. The larger the camera chip, the greater the depth of field.

Fourth, the chip size of the machine vision lens

To determine the chip size of the matching industrial camera, the maximum lens adapter size must be larger than the camera chip size, otherwise it will cause distortion.

Five, the interface of the machine vision lens

Camera and lens interfaces need to be always, mainly C, CS, F interfaces

Six, the focal length of the machine vision lens

The focal length of the lens has a major impact on the field of view and working distance. Factors such as field of view, working distance, and camera chip size must be determined before determining the focal length of the machine vision lens.

Distortion of machine vision lens

Distortion is image distortion caused by inconsistent local magnification in the field of view. Due to the influence of the production process, lens distortion is inevitable. The better the lens, the smaller the distortion. Generally, in the case of high accuracy requirements such as precision measurement systems, the distortion of the machine vision lens must be considered.