"?"
Looking at Xu Yun with a mysterious expression.
Faraday instinctively glanced at his hand.
At this moment.
In the open palm of Xu Yun's hand lay a transparent crystal.
The crystal was about the size of a mint candy in a Green Arrow metal box, with high light transmission.
At this moment, the crystal had been polished into a rectangular shape, tapered at both ends and even in the middle, somewhat resembling a butt plug.
Faraday reached out to touch it a few times, feeling the matte texture, and judged:
"Is this... a crystal?"
Xu Yun shook his head. Nine out of ten people would mistake this thing for a crystal at first glance and explained:
"Mr. Faraday, this is material prepared for me by Dean William Whewell, called a nonlinear optical crystal.
"It can be used to assist in changing the frequency of light. We have prepared seven pieces, and you will soon understand their specific function."
Nonlinear optical crystal.
