This article discusses mounting a legacy Optical monitor as a tabletop monitor

Elo does not recommend mounting Optical IDS Monitors in a tabletop configuration. This is due to the 4-cameras that are mounted in the corners of the monitor. Tabletop mounting will cause the monitor's frame to distort thereby causing the cameras to come out of alignment which leads to touch failure. 

The preferred mounting method for Optical IDS Monitors is wall mounting.