Disney's Adventures of the Gummi Bears - Season 1 - Eps 21: Light Makes Right
The Gummies find a Gummiscope, a gigantic machine that harnesses sunlight as a means of long-range communication, that could allow them to make contact with the Great Gummis across the ocean – but it can also be used as a weapon, causing Duke Igthorn to use it as a laser-type weapon to force King Gregor into surrender.
About Disney's Adventures of the Gummi Bears

Title: Disney's Adventures of the Gummi Bears
First Air Date: 1985-09-14
Last Air Date: 1991-02-22
Status: Ended
Rating: 7.4/10 (from 232 votes)
Language: EN
Seasons: 6
Total Episodes: 95
Network: ABC NBC Syndication
Genres: Animation, Family, Kids
Production Companies: Walt Disney Television, Tokyo Movie Shinsha
Synopsis
Join the world’s sweetest heroes for high adventure in a mystical land of giants and wizards, ogres and dragons, and wondrous creatures both good and evil. Meet Gruffi, Zummi, Cubbi, Grammi, Tummi, Sunni, and all the legendary Gummis as they laugh, play, foil dastardly plots, and fight for what's right.
Cast

June Foray
Grammi Gummi (voice)

Lorenzo Music
Tummi Gummi (voice)

Katie Leigh
Sunni Gummi (voice)

Jim Cummings
Zummi Gummi (voice)

Noelle North
Cubbi Gummi / Princess Calla (voice)

Michael Rye
Duke Igthorn / King Gregor (voice)

Will Ryan
Unwin / Ogres (voice)

Corey Burton
Gruffi Gummi (voice)

Brian Cummings
Sir Tuxford / Artie Deco (voice)