Highly Accurate Particle Measuring Using Lasers

Particle measuring is the process of counting and sizing particulates in a sample and is performed in either air or liquid. This technique is prominent in industrial processes such as semiconductor wafer fabrication, where high fluidic purity is a requirement and where the presence of particulate contaminants can lead to product waste or system damage.

The Challenge

In a semiconductor wafer fabrication process, particle measurement is used to ensure that chemical, cooling and cleaning fluids are free from such contaminants. Industries such as these begin to leverage the power of particle measuring against contamination. This results in size and space of the equipment required to perform this analysis starting to become an issue. OEMs and system integrators need ease of integration without incurring costly platform redesigns. Liquid particle measuring is performed by specialist instrumentation that can be integrated into the production line. Such instruments are equipped with high power lasers. These lasers deliver a balance of high power and low noise in a compact, high reliability platform.

How Does Particle Measuring Work?

Particulates can be present in a range of sizes and materials. Determining the properties of the contaminant is therefore critical in understanding its presence and possible source of contamination. In order to accurately determine contaminant properties, air-cooled laser solutions are employed. The laser, and either an array detector or CCD camera analyses the diffracted light which then determines the properties of the particles passing between them. Depending on the required power, a 532 nm gem or opus laser from Laser Quantum is perfectly matched to this application. The laser beam is directed through a flow cell at an angle perpendicular to the liquid flow. The beam is precisely directed through the liquid to a pin hole aperture with beam dump. Any particles that strike the laser beam cause the light to be diffracted away from this beam dump.

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