ProMetric® I-SC Solution

Two Measurement Systems in One

The ProMetric I-SC Solution provides a single platform for measuring spectral data, luminance (cd/m²), and chromaticity (CIE xy and u’v’) to evaluate the appearance of light-emitting devices such as displays, illuminated components, and light sources. The ProMetric I-SC Solution uses a polarization-insensitive mirror to combine the functions of an enhanced tristimulus imaging colorimeter (ProMetric I-series from Radiant) with a high-end spectroradiometer (CAS 140D from Instrument Systems GmbH). This innovative design is based on patented technology developed by Radiant Vision Systems (US Patent No 8482652). Combining two systems into one solution, the ProMetric I-SC enables manufacturers to deploy complete light and color measurement functions with ease and efficiency.

ProMetric I Imaging Colorimeter Advantages

The ProMetric I-SC Solution leverages the advantages of Radiant’s ProMetric I Imaging Colorimeter for light and color measurement. ProMetric I systems offer leading imaging performance for metrology applications and are purpose built for manufacturing inspection to meet speed and accuracy demands from R&D to production. The ProMetric I61 (61-megapixel) Imaging Colorimeter captures a complete device in a single image for fast and precise measurement of all regions of interest—down to areas as small as a display subpixel. The built-in tristimulus color filter wheel of the ProMetric I provides a system response innately close to CIE color-matching functions, with each color channel of the system having near-perfect alignment to each CIE response curve. This allows the system to maintain accuracy even when a device exhibits slight color shifts from the initial calibration point, extending the effectiveness of each system calibration. ProMetric I also optimizes measurement speed, capturing the greatest amount of data with the highest accuracy per data point in less than 2 seconds per full-color measurement. 

Illustration of the innate spectral response of the ProMetric I Imaging Colorimeter for each color channel (dotted lines) as compared to the standard CIE color-matching functions (solid lines).

The ProMetric I-SC solution also leverages the optical configurations of the ProMetric I-series imaging colorimeter to enable spectral and spatial measurements within unique contexts. For example, the ProMetric I-SC can be applied with Radiant’s AR/VR Lens to capture measurement data from inside augmented and virtual reality headsets, at the near-eye position. Not only does this configuration enable evaluation of spatial luminance, chromaticity, and defects across the angular field of view, but also places the spectral measurement point inside the headset to capture highly accurate spectral data.

Highly Accurate Spectral Data

Spectral data can be acquired by the ProMetric I-SC solution by capturing an image of the device under test using the imaging colorimeter and directing light from a center point on the device through the fiber-optic cable to the spectrometer. The spectrometer evaluates individual wavelengths of the light beam (380-780 nm) to provide a highly accurate spectral measurement. This data can be used to determine:

• Correlated color temperature (CCT)
• Color rendering index (CRI)
• Spectral distribution
• Spectral bandwidth (i.e., at full-width half-maximum (FWHM))
• Peak wavelength
• Dominant wavelength

Spectral values are measured from a center point within the measurement image captured by the integrated imaging colorimeter. Within the context of an image, the exact coordinates of the spectral measurement can be known and applied for extremely accurate positioning of this point relative to the device under test. The spatial position of the spectral measurement point is output in x,y coordinates as well as angular degrees, for example for measuring within AR/VR headsets. The measurement point and field of view of the connected spectrometer are also shown on the measurement image in software as a graphical element (circle or rectangle) for quick contextual visualization.

Spectral data can be used to characterize device output, monitor changes in emission spectra, and evaluate devices against defined tolerances. Spectral data can also be stored, exported, or used as a reference to calibrate the connected imaging colorimeter’s response according to CIE color-matching functions for new devices and device states (i.e., a different-colored display or backlit component).

Field of view of the integrated spectrometer shown as a circle in the center of the measurement image in software, located at a specified x,y measurement point.

Engineered to Maximize Capability and Utility

Some applications require the capabilities of both a spectrometer and an imaging system for device qualification—the spectrometer providing highly accurate values of correlated color temperature (CCT), color rendering index (CRI), etc.; the imaging system providing precise luminance (cd/m²), chromaticity (CIE xy or u’v’), and visual inspection for all points across an image. If imaging systems and spectrometers are applied separately, manufacturers must source and purchase both systems and can only apply one system at a time for measurement, requiring multiple stations or processes. In these cases, manual setup and data transfer can cause significant downtime or introduce errors at any stage.

With the ProMetric I-SC, Radiant offers the advantage of both systems’ capabilities in one solution, eliminating the burden of purchasing multiple systems or learning separate platforms. Direct integration also enables system functionality without manual intervention. Measure spectral and spatial data at the exact same point on a source, monitor output, and directly apply color calibrations, without moving equipment. 

Combining system capabilities in the ProMetric I-SC also maximizes capability of the solution as a whole. Through the context of measurement images, users can define and view the precise location of the spectrometer’s spectral measurement point (not possible when using a spectrometer separate from an imaging system). Similarly, because the spectrometer uses the imaging colorimeter’s optics, it can acquire spectral data in any area visible to the imager from the same relative position and angle. 

Intuitive Software Interface and Data Visualization

The ProMetric I-SC Solution works with Radiant’s TrueTest™ Software and application-specific software modules for automated visual inspection, measurement, equipment control, and communications. TrueTest offers the comprehensive range of Radiant’s display measurement capability and the ability to sequence tests for rapid, automated evaluation of all relevant display characteristics in a matter of seconds. From TrueTest, users can initiate a calibration of the ProMetric I-SC and set calibration operations to run automatically. The TrueTest interface includes a unique view to visualize spectral data captured by the connected spectrometer and compare or output data points.

The spectral data window in TrueTest Software shows the CIE 1931 chromaticity coordinates and spectral plot for data captured by the ProMetric I-SC Solution’s integrated spectrometer. The above image plots the spectral data measured at the center of a white OLED display.

ProMetric I-SC Solution Key Features and Highlights:

• Combination imaging colorimeter/spectrometer for fast and accurate color measurement
• Spectral measurement capability, data visualization, and output
• CIE-matched color filters for measuring luminance and chromaticity values precisely correlated with human visual perception
• On-demand or automatic calibration based on user-defined settings in software
• High-speed measurement and communications to support manufacturing demands
• Integrated with an enhanced ProMetric I61 Imaging Colorimeter (61-megapixel resolution)
• Compatible with Radiant’s AR/VR Lens and XRE Lens for in-headset calibration and measurement
• Compatible with Radiant's FPD Conoscope Lens for high-resolution angular measurement
• Seamless operation with TrueTest software packages
• Easy-to-use interface for visualizing, applying, and exporting spectral and colorimetric measurement data