QR code and dewar flask: what they have in common

1. Step 1. QR code — evolved from — Barcode. A two-dimensional barcode.
2. Step 2. Barcode — uses — Laser diode. Barcode scanners use lasers.
3. Step 3. Laser diode — is a kind of — Laser. A semiconductor laser.
4. Step 4. Laser — has part — Mirror. A resonator made of mirrors.
5. Step 5. Mirror — is part of — Vacuum flask. The silvering reflects heat radiation.
6. Step 6. Vacuum flask — evolved from — Dewar flask. A household Dewar flask.

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