How to choose the right machine vision lens

Can produce an image that exactly matches the subject, including all details and brightness changes. A standard lens may be approximately 1 million pixels in a fixed focal length of 4.5-100mm. The macro lens is optimized for close focus. Telecentric lenses are used for speialized metrology applications. They are used to eliminate dimensional and geometric changes. Schnuck is relatively strict in the selection of machine vision lenses, mainly through the following aspects to evaluate 1. Calculate the focal length When choosing the correct lens for the application, the designer uses 3 factors to calculate the required working distance: focal length, length of the object being inspected, and sensor size. The required working distance can also be calculated using the size of the objective lens and the opening angle of the lens. The object distance refers to the distance between the object and the first principal plane of the lens group in the optical system. The distance can only be calculated by spcifying the position and distance of the two main planes and the actual lens length. 2. Choose the right machine vision camera The latest advances in machine vision technology now enable cameras to transmit high-megapixel images at fast frame rates. Choosing the best interface requires reviewing the following points. 3. Choose a sensor type (CMOS or CCD) The line between charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) sensors is blurring. Traditionally, CCD has higher image quality, better sensitivity, better noise performance and ideal global shutter. CMOS sensors are known for their high speed, system-on-chip integration and low manufacturing cost. But CMOS sensors have shown a significant improvement in quality. 4. Color camera or black and white camera Many vision systems use color cameras because users are more satisfied with color images. Some designers think that the cost of monochrome cameras is lower, but this is not always true. It is not always necessary to use a color camera to distinguish several colors. Processing time, resolution, pass/fail accuracy, power consumption and cost must all be taken into consideration. 5. Camera output format It's not just a matter of choosing the "fastest" interface available. The compatibility with existing systems and integration with other available technologies must be considered. Some interfaces allow "hot swapping", while other interfaces may require a complete shutdown of the system. Engineers must consider cable length and signal attenuation as well as power requirements. 6. Frame rate The output format will affect the frame rate the system will achieve. When choosing any other camera factor, calculating the frame rate required by the application is critical.