This article deals with the measurement of small symbols and display segments, which can be performed with the spectroradiometer JETI specbos 2501-focus and the accessory add-on optics.
The main application for light measurements in Luminance mode (directed measurement) are extended homogenious light sources as monitors or cinema projections. Sometimes the task is to measure small spots or structures, e.g. the symbols on illuminated control switches or alphanumeric displays.
specbos 2501-focus can measure spot sizes of 4 mm and more. But it is possible to equip them with an add-on optic creating a measuring spot of 3 mm, 1 mm diameter and 0.5 mm. The measuring distances are fixed.
Three focusing optics for measurements of 3 mm, 1 mm and 0.5 mm diameter are available. The measuring spot is still marked by a red circle. The 0.5 mm version is fitted out with a magnifying glass to simplify the precise adjustment.
All add-on optics can easily be attached to the basic instrument by screwing. The accessory is automatically detected and the appropriate calibration data will be applied.
Measurement of a display segment with JETI spectraval 1501-focus (discontinued)
| Add-on optics | Measuring diameter | Measuring distance (from front face of the optics) | Field of view | Length of optics |
| #1 |
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| #2 |
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| #3 |
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| Add-on optics #1 | Measuring diameter
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Measuring distance (from front face of the optics)
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Field of view
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Length of optics
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| Add-on optics #2 | Measuring diameter
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Measuring distance (from front face of the optics)
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Field of view
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Length of optics
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| Add-on optics #3 | Measuring diameter
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Measuring distance (from front face of the optics)
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Field of view
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Length of optics
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Remark: The add-on optics cannot be used with a standard spectraval or specbos device, always the focus version must be used.