The Chinese magic mirror (simplified Chinese: 透光镜; traditional Chinese: 透光鏡; pinyin: tòu guāng jìng) traces back to at least the 5th century, although their existence during the Han dynasty (206 BC – 24 AD) has been claimed. The mirrors were made out of solid bronze. The front was polished and could be used as a mirror, while the back has a design cast in the bronze, or other decoration. When sunlight or other bright light shines onto the mirror, the mirror appears to become transparent. If that light is reflected from the mirror onto a wall, the pattern on the back of the mirror is then projected onto the wall.
Bronze mirrors were the standard in many Eurasian cultures, but most lacked this characteristic, as did most Chinese bronze mirrors.