Measuring Luminous Intensity or Acceleration Levels in a Micro-g Environment Using Spider


Crystal Instruments products support a wide range of sensors and their measurement quantities. With the introduction of the Spider-80SGi (a general-purpose data acquisition device), using a customizable excitation voltage has substantially increased the range of sensors that can be interfaced to the Spider platform of devices.

Owing to these capabilities, the Spider platform of devices has been used for the acquisition of measurement quantities that are not typical in the vibration industry, such as luminous intensity. Quantities and units available for selection within the EDM software often fall short in these scenarios. With such applications in foresight, Crystal Instruments introduced a feature with which the users could add custom Measurement Quantities and use these customized measurement quantities to define the sensitivity and acquire data.

Measurement Quantities could be easily added using the Physical Dimensions of the quantity being added as shown below:

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Any physical quantity could be resolved into a combination of the base quantities. When a new quantity is added to the list, it is important to add the physical dimensions of the quantity except for the dimension less quantities.

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Considering an example of Torque (or Moment of Force) which is Force times the Distance would be measured in Nm (Newton – meter) would have the units: Kg m2/s2. Thus, the physical dimensions would be ML2T-2. Any number of such physical quantities that are not available by default could be added.

In yet few other applications, it is required to have additional Units to the existing measurement quantities or the customized measurement quantities. In yet other applications, scaled versions of existing quantities are useful in measuring very low or very high extremes of any quantity. As an example, using µg would be helpful in interpreting measurement of acceleration in simulated microgravity environment. To accommodate these applications, EDM has also been equipped with adding units to Measurement quantities alongside the ability to add customized Measurement Quantities.

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Customized units can be added by using the reference unit and entering the scaling factor and/or the offset. For example, Temperature could be conveniently displayed in oF from K, but scaling it using a factor of 9/5 and adding an offset of -459.67.

Similarly, Acceleration could be displayed in µg by scaling Acceleration in g by 1e-6.

Temperature measurement in oF from a Temperature chamber

Temperature measurement in oF from a Temperature chamber