如何量度粉末/顆粒的大小

請問:
家庭式小工廠, 在研磨大米使之變成米粉的過程中, 如何簡單地量度米粉顆粒的大小?

謝謝

Question:
In a small rice-grinding shop, how do we measure the particle size of the ground rice powder (using affordable methodology and equipment)?

Thanks a bunch.