Correct option is D
The ruby rod used in lasers is made of
aluminium oxide (Al₂O₃) doped with a small amount of
chromium ions (Cr³⁺). The chromium ions give the ruby its characteristic red color and enable it to emit laser light when excited.
Key Points:
· Ruby lasers are the first type of lasers invented (Theodore Maiman, 1960).
· It operates in the red region of the spectrum, at
694.3 nm.
· It is a
solid-state laser.
· Ruby lasers are used in applications such as holography and range finding.
