Obtaining Accurate Measurements with the CL-500A Illuminance Spectrophotometer

The Konica Minolta CL-500A illuminance spectrophotometer is a device which can measure the general color rendering index (CRI), as well as individual color rendering indexes R1-R15 and the Scoptopic-Photopic (S/P) ratio. The CL-500A is also the first portable spectrophotometer in the world to conform to both DIN and JIS standards. Besides being lightweight, the CL-500A is also an extremely flexible tool. The device can be used as a standalone product in the field or in the lab, and can also be used in conjunction with data management software. Since the CL-500A is a sensor-based instrument, it can accurately measure narrow bandwidth emitters such as LED, OLED, and gas-discharge light sources. In order to ensure that luminance, CRI, and spectral measurements are accurate when using the CL-500A, a few simple guidelines should be followed.

Ensure that the CL-500A has been properly maintained. This may seem like an obvious step, but many equipment technicians assume that their equipment has been maintained when they use it, and this can lead to incorrect and inaccurate measurements if the maintenance schedule has been ignored. Always follow manufacturer guidelines for maintenance, and make sure that any repairs or calibrations are conducted by a manufacturer-authorized facility. This ensures not only that warranties will be honored, but that the components used for repairs are up to the manufacturer’s specifications.

Calibrate the CL-500A before each use, when the light sources are different, or when the device has been moved. Because even small vibrations and shocks can cause discrepancies in the sensors, it is necessary to ensure proper calibration every time you use the CL-500A. Ensuring that calibration has been completed will help make readings more accurate, and will save time by eliminating extra readings. An internal light source allows the CL-500A to accurately preform a self-calibration in under 30 seconds.

Carefully document the distance and angle between the sensor and the light source. Knowing the distance and angle between the sensor and the light source is important not only for obtaining accurate results, but also to ensure that the device is properly calibrated. Because differences in the distance can cause discrepancies in measurements, a small difference in the distance between two sensors could cause results to appear imprecise. The measurement plane must also remain constant in relation to the light source to avoid improper readings. Differences in distance and angle between the device and the light source can cause measurement error and inconsistencies.

Divide large spaces or rooms into a grid. Because there are many factors which can influence the amount of light in a given space, and because it will be difficult to determine the best place to take a reading in a big area, it is usually a good idea to divide large spaces into a grid and take readings from each grid square. Once the measurements have been taken, you can simply average the readings to get the average illuminance in the space.

Regardless of the application, it is important to remember that the CL-500A is a precision instrument. Though it is an easy to use, robust device which can withstand reasonable abuse, getting accurate readings will take attention to detail and patience. However, taking a little extra time and following the steps mentioned here will go a long way in making accurate, repeatable readings with each lighting project. For more information on the Konica Minolta CL-500A illuminance spectrophotometer, click here.

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