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Technical resource

PSL and silica answer different metrology questions.

Particle size alone does not make two materials equivalent to an optical inspection system or process study.

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Material comparison

Comparison

FactorPSLSilica
MaterialPolymer sphereInorganic silica
Common roleControlled size reference and instrument calibrationInorganic contamination and optical/process challenge
Density and handlingLower density; suspension behavior depends on formulationHigher density; aggregation and deposition control are important
Selection basisInstrument method and size-response requirementProcess representation and optical/material requirement
Optical response

Do not infer equivalent response

Equal nominal size does not guarantee equal signal. Refractive index, shape, substrate interaction and the inspection system affect response.

Method control

Use the material named in the method

Where the instrument procedure, customer specification or validation method defines the particle material, substitution requires technical justification.

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