8540.89.00.60 - Light-sensing tubes

This HTS category, 8540.89.00.60, specifically covers "light-sensing tubes." These are vacuum or gas-filled electronic tubes designed to detect and respond to light by emitting electrons or altering their electrical conductivity. This typically includes devices such as phototubes, photomultiplier tubes, and photocells, which are integral components in a variety of sensing and imaging applications across industries.

This classification distinguishes itself from its siblings by its specific function. While other categories within 8540.89.00 cover general gas and vapor electron tubes, or specific types like diodes, triodes, and tetrodes, this category is precisely for tubes whose primary operational characteristic is their sensitivity to light. Therefore, tubes that primarily operate based on electron emission due to light stimulation, rather than as general signal amplifiers or rectifiers, would fall here.

As this is a leaf node, there are no further subcategories. Classification into this specific code relies on the confirmed function of the tube as a light sensor. Importers and exporters should ensure that the product's primary design and intended use are for the detection or measurement of light to accurately apply this tariff heading.