UV light, typically at wavelengths of 365nm-405nm, is used to excite a UV-sensitive material, optical brightener, or tracer, making it fluoresce and emit light at a visible wavelength. The visible light is typically emitted between 470nm and 530nm. It is the emitted visible light that the imaging camera will use to inspect the image and determine pass or fail.
In the following examples, UV light and the resulting visible emitted light are used to determine whether the tamper seal has been applied to the bottle, whether an adhesive has been applied to an electronic component, and whether lithium grease has been applied to the gear teeth. All of these applied materials are sensitive to UV light and are able to be imaged and inspected at a visible wavelength.
A bandpass filter is used on the camera’s lens to pass only the wavelength at which the sample emits visible light. This reduces the amount of blue UV and ambient light visible in the captured image, enhancing the emitted wavelength.
Additional applications include the inspection of special inks, dye penetrant inspection, coating inspection, glue presence detection, and flux presence detection.
A multi-wavelength approach to configuring an Ultra-Violet imaging system, provided in TPL’s Fluorescence Imaging Solution (FIS), lets the user experiment with finding the best combination of UV wavelengths to achieve the highest fluorescence and image contrast between the emitting material and its background.
The dome-effect minimizes reflections from complex surfaces and coated documents.
White LEDs are built-in for secondary inspection. The built-in LP415nm filter ensures only visible light exits the top of the dome, enhancing safety. A bandpass filter with an M27 thread may be used on top of the built-in filter to permit only the emitting wavelength to pass to the camera.
The TPL FIS is used to enhance the imaging of inks on tax stamps, bank note inspection, glue seal inspection, security features inspection, and much more.
The new UV3/VL3 Series offers a range of high-intensity UV illumination optimized for smaller fields-of-view. Ring lights, including one that’s IP67-rated, small bar lights, and a spot-light can be configured according the coverage area and UV wavelength that’s most effective in exciting the visible light fluorescence.
The RL208 Series and the RL113, RL121, and RL127 Ring Lights feature MicroBrite™ and other high-current and medium-current LEDs and are available in a range of ring light diameters.
MicroBrite™ expandable bar lights deliver high performance in a compact form factor. They are available in 3” increments from 3” (75mm) to 18” (450mm) lengths.
Please contact R.J. Wilson, Inc. to discuss whether UV Lighting can be a benefit to your imaging process.