検査・光学
transmitted-light check
Japanese: 透過観察
A basic inspection to check for air bubbles, veins, opacity, and uneven color by holding the item up to the light.
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Transmitted light inspection is a method used to check finished glass works for internal defects—such as scratches, air bubbles, loss of transparency, uneven coloring, and residual stress—by passing light through them. By holding the piece up to natural light or a dedicated light box, internal defects that are difficult to see under reflected light can be visually detected.
Polarized transmitted light inspection using polarizing plates (Polarroid filters) is particularly effective for checking residual stress. When two polarizing filters are placed in a crossed Nicol configuration (at a 90-degree angle) to sandwich the piece, areas with residual stress appear to glow brightly. By performing transmitted light inspection on all finished pieces before shipment or exhibition, you can ensure consistent quality in your work.
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.