The new process is called “Spatial RAM” due to its use of a RAM memory chip to hold predetermined data acquisition locations and its reliance on an external sensor that monitors the probe of the measuring instrument as it moves through space.
The Spatial RAM circuitry commands the measuring instrument to record data on some property of the product, such as a semiconductor chip, whenever the external sensor detects a match with the preloaded value in the RAM. Unlike data collection based on presumed probe speed -- which can be incorrect if the probe movements are changed by conditions such as temperature changes or gradients -- Spatial RAM always collects the data where it is needed.
NIST’s Tom Wheatley, who devised the patented technique with colleague Clayton Teague, said, “Even tiny changes in high precision data collection can be detrimental in manufacturing today’s miniaturized machine parts. The Spatial RAM system avoids this potential problem by simplifying the measuring process. Because data acquisition values are loaded into the RAM operating circuitry, the sensor or probe does not have to be at a particular spot at a particular time to acquire the data from that particular spot. Anytime the probe arrives at the spot is the right time.”
Since Spatial RAM allows for any data value to be loaded and matched, manufacturers also can create non-uniform or unequal spacing over samples or use values that compensate for known errors.
For more information, contact Tom Wheatley at (301) 975-3449.