Although the tricorder would eventually come to be an invaluable tool in the Starfleet universe, it started out as a plot device meant to increase the relevance of the ship’s yeoman in “The Original Series,” according to a production note revealed in “The Making of Star Trek.” Sent from “Star Trek” creator Gene Roddenberry to producer Robert H. Justman on April 14, 1966, the note considered ideas for expanding Yeoman Janice Rand’s (Grace Lee Whitney) role, writing, “It has been suggested that she carry as part of her regular equipment […] some sort of neat, over-the-shoulder recorder-electronic camera via which she can take log entries from the Captain at any time, make electronic moving photos of things, places, etc.” (p. 169). In the same note, Roddenberry suggested a second use for this type of equipment: as a toy for “female-type children.”
Those simple functions would soon be expanded to include the tricorder’s three main functions. According to the “Star Fleet Medical Reference Guide,” the “diagnose” function of the medical tricorder works almost exactly as the sick bay scanner would right down to the vital signs readout. “Analyze” allows users to evaluate information in more detail, ascertaining details like what type of bacterial organism they are dealing with or taking a much closer look at blood composition. And “record” allows users to record that data.
Although the tech would eventually change in-universe, Yeoman Rand’s model would have a lasting impact on generations of Starfleet officers to come. Just as humans today often wax nostalgic over their favorite vintage technology, trill Starfleet officer Jadzia Dax (Terry Farrell) revealed how much she admired the classic design of the 23rd century model in the “Star Trek: Deep Space Nine” episode “Trials and Tribble-ations.”
