Selecting a Light Measurement Solution: 7 Critical Parameters

Tue, November 8, 2016
Radiant Vision Systems  | 

Measuring Light Chromaticity and LuminancePrecision measurement of luminance and chromaticity in information displays, light sources, or other light emitting or reflecting materials requires careful consideration of application requirements in order to identify the optimal light measurement system for the job. Resolution, imaging speed, and other parameters should be carefully weighed when designing a system. Imaging colorimeters are high sensitivity, high-accuracy CCD-based imaging systems and with multiple sensor, filter, and lens options available, and these systems can be optimized to meet the specific needs of an application. The priority of each of the following parameters should serve as a guide for selecting a colorimeter-based system:


Color AccuracyColor Accuracy: The ability to accurately match measurements to a color coordinate system, such as the CIE or L*a*b* Color Space.
Luminance AccuracyLuminance Accuracy: Absolute accuracy of luminance measurements; calibration compensates for system noise and photopic filter accuracy.
Dynamic RangeDynamic Range: The number of shades of gray into which the system divides luminance measurements. Larger dynamic range plus low measurement noise yields greater precision and higher contrast ratios in a single image.
Pixel ResolutionPixel Resolution: Distinguish fine detail within images. For a given field of view, higher CCD pixel resolution means greater spatial detail.
Imaging and Readout SpeedImaging and Readout Speed: Time required to capture and readout images from the CCD. A trade-off exists between speed, noise and captured image detail.
Interline vs. Full FrameInterline vs. Full Frame: Interline CCDs allow faster imaging and lower inspection cost while providing image data, dynamic range, and noise appropriate to the application.
Field of View and Aspect RatioField of View and Aspect Ratio: CCD size and lens specs determine the field of view parameters. Field-of-view, in turn, determines the required distance between the imaging colorimeter and object. The CCD aspect ratio - square or rectangular – is chosen to be appropriate to the application.