With VST, we have prepared an optional item to change the field of view and WD by mounting it on a standard lens. Extension ring and rear converter lens
Lighting Selection
As manufacturing technology has advanced in recent years, various products can be mass-produced in a short period of time. As a result, "product inspections" are no longer able to keep up with visual inspections by humans due to the demand for higher accuracy, inspection speed, and difficulty in training new employees. Replacement of visual inspection is underway with machine vision (image processing equipment), which inspects products for defects based on image data captured by industrial cameras and lenses. Machine vision has many advantages, such as 24-hour operation, programmable operation, and reduced variation in inspection results. However, machine vision is not simply a matter of installing cameras. In fact, the human eye excels in its ability to constantly focus on a product depending on its distance and viewing angle, and it is able to recognize both bright and dark areas in a single glance. It can flexibly respond to any given situation. In contrast, machine vision often requires a single image of the product being delivered by a fixed camera, lens, and lighting, and unless the defective part is clearly visible in the image, it is impossible to correctly determine whether the product passed or failed. By understanding "what" and "how" you want to see the product, and by selecting and placing the optimal camera, lens, and lighting in the necessary positions, taking into consideration making the inspection and defect points of the product stand out well and, conversely, making features unnecessary for inspection as inconspicuous as possible, you can obtain a "good image that shows what you want to see". This is the first step toward stable machine vision operation.
Extension ring
Rear converter lens
Extension ring is mainly attached between the lens and the camera when imaging in close proximity with a CCTV lens. By extending the position of the camera and lens, the focus position (WD) of the lens will become in the proximity range. The FOV range is also reduced [see Figure 1-3 (a)]. Our SV-EXR series has a wide range of 12 types of rings ranging from 0.2 mm spacer rings to 50 mm rings. ❶Extension ring SV-EXR Series
What is a good image?
Figure 1-3 (a) Extension ring
There is a cylindrical container with a picture of a bird printed on it. Let's capture an image of this with a combination of lens + camera + lighting. What is the difference between a good image and a bad image?
Good image
Bad image
Shorten WD and increase magnification
Rear converter is mounted between the lens and camera to easily increase the magnification (reduce the FOV) without changing the WD. However, if the magnification is increased, the brightness will be reduced (1/reduced by the square of the lens magnification). We have a lineup of SV-X series lenses from 1.5x to 5x. ❷Rear converter lens SV-X Series
There are four main factors VSTdefines as the conditions for a good image.
Figure 1-3 (b) Rear converter lens
❶ Resolution ❷ Focus ❸ Contrast ❹ Brightness uniformity
Increase the magnification with a constant WD
We will explain on the next page what should be taken into account in order to obtain good images.
184
185
Made with FlippingBook Ebook Creator