The visual quality of a backlit component is determined equally by the photometric and dimensional properties of its illuminated regions. Backlit components often include symbols and characters on analog controls, such as buttons on electronics and appliances and keys on keypads. These components may also be illuminated shapes like halos around USB ports or decorative light strips in vehicle interiors, taking a range of forms.
Evaluating the quality of these components is challenging for image analysis software because of the unpredictable and bespoke nature of the shapes and symbols that must be registered, the need for defect detection based on these shapes, and the need to additionally measure brightness, color, and uniformity as part of overall visual quality.
Due to the multiple inspection criteria, the process of evaluating backlit components has historically relied on either human inspection or the combination of systems – machine vision (traditionally applied to identify characters or shapes within two-dimensional images) and photometric systems (designed to measure values of light, such as brightness and color).
While human inspection lacks objective and quantifiable inspection data, a combination of machine vision and photometric systems is costly and complex. Each system accomplishes only part of the quality control objective. Further, the photometric system’s measurements lack precision because it is unable to rely on the machine vision system for contextual information about the area and shape of the illuminated region.
Released in May 2020, Radiant’s VIP Software provides an all-in-one solution for backlit symbol inspection that simultaneously performs photometric measurement with machine vision-based registration and defect detection. Leveraging a scientific-grade imaging photometer or colorimeter from Radiant, VIP measures absolute values of luminance (Lv, cd/m2), chromaticity (CIE xy, u’v’), L*a*b* color scale, Correlated Color Temperature (CCT), and dominant wavelength (nm) to evaluate symbol brightness, color, and uniformity.
Advanced registration functionality in VIP dynamically applies unique inspection regions, called regions of interest (ROI), to match the exact shape of each illuminated element regardless of component position or orientation. Precise ROI enable VIP to measure the exact brightness, color, and uniformity values of each element or symbol and detect defects within the ROI, identifying issues in substrate etch (ROI shape completeness and integrity), dead LEDs, poorly diffused backlight, and particles within substrate layers.
According to Radiant, by combining photometric and machine vision capabilities, VIP Software greatly reduces time and cost for lab testing and production-level quality control. Manufacturers who utilize VIP benefit from a single camera/software system that evaluates all visual qualities of backlit components out of the box. The solution provides quantifiable and objective data, rapid pass/fail routines, and easy integration into automated systems and inline inspection operations.
“On behalf of the Laser Focus World Innovators Awards, I would like to congratulate Radiant Vision Systems on their Silver-level honoree status,” said Laser Focus Word publisher Paul Andrews. “This competitive program allows Laser Focus World to celebrate and recognize the most innovative products impacting the photonics community this year.”