Multi-Focus Optics (Patent Listed) The highly accurate and reliable detection pattern will maintain its sensitivity throughout the entire detection area, even in high temperature or low contrast environments. Multi-Focus Optics create an extremely high vertical zone density, two or three times the size of conventional PIRs. These taller zones capture the entire body mass and enable detection of even the smallest temperature contrast against the temperature of the background. In addition, the vertical detection density has been improved to take into account dead zones created by furniture or partitions.