Views: 0 Author: Site Editor Publish Time: 2022-08-31 Origin: Site
Product Quality Control
Many pharmaceutical powders need to be tested for foreign matter before they are compressed into tablets. Conventional dome illumination provides uniform illumination of the powder, and wavelengths can be selected to provide the best contrast between powder and contamination. Foreign objects in the vial-filled solution can be identified by detecting the liquid using high-intensity directional illumination from a spotlight located at the bottom of the vial. Some opaque liquids may be transparent to infrared light, so infrared illumination can be used to reveal contaminants.
Tablets can also be inspected for dirt or other surface defects using a high-angle ring light that provides bright on-site illumination. Light from surface textures and features, such as scratches and imperfections, bounce off the camera, so they appear as dark features on a bright background. The low-angle ring light provides darkfield illumination that highlights surface features because the camera only picks up light scattered by surface imperfections. This is useful in applications such as internal inspection of vial caps, edge detection, identifying O-ring defects, and reading doses and other information printed on the surface of a tablet.
Packaging inspection
A major problem facing package inspection is reflections from the packaging material, which makes it difficult to obtain acceptable images, especially when the package surface is uneven. Traditional dome and flat dome lights provide even, diffuse illumination to minimize glare and shadows, making uneven surfaces appear flat, enabling the imaging of codes and text printed on packaging. Flat dome lights produce the effect of a dome light in a thin housing package, do not require a hole for the camera, and take up less space than a dome light. In addition, the choice of wavelength is also critical to enhance the contrast of the print against the background.
In some cases, the code and text may be cross-printed and cannot be imaged separately using traditional methods. At this point, photometric stereovision (part of a broader multi-lens computational imaging technology) can provide a solution. A single image is acquired by sequentially illuminating each segment of a four-segment ring or square light. Key data is extracted from each image and combined with the object's 2D texture or surface color to isolate the object's shape. In this way, the superimposed code and text can be separated.
Sometimes, it is necessary to detect the amount of liquid filled in the container. To measure the fill level of clear liquids in clear containers with reflective surfaces, such as vials, ampoules, and IV bags, a flat panel light is used to illuminate the container from behind. The meniscus of the liquid is clearly shown in the image as a black line. Occasionally, the container containing the liquid is not completely transparent, and it is necessary to use wavelengths outside the visible range for measurement. For example, some contact lenses absorb UV light, and high output UV light sources can be used to image contact lenses inside the package. Near-infrared (NIR) and short-wave infrared (SWIR) light can also penetrate many packaging materials, making them important for viewing the contents of a package.
