The Voight-Kampff is a polygraph-like machine used by Blade Runners to assist in the testing of an individual to determine if they are a replicant. It measures bodily functions such as respiration, blush response, heart rate, and eye movement in response to emotionally provocative questions.
Use of the Machine
In the film two replicants take the test, Leon and Rachael, and Deckard tells Tyrell that it usually takes 20 to 30 cross-referenced questions to distinguish a replicant; in contrast with the book, where it is stated it only takes "six or seven" questions to make a determination. In the film it takes more than one hundred questions to determine if Rachael is a replicant.
Ready Player One History
The Voight-Kampff machine is found in the template of any Tyrell Building, and is used to reach the Second Gate. Unless said building is changed, there's five security checkpoints to pass, and about 50 NPC guards.