An optical reader system 7 for diffraction grating-based encoded microbeads (or bead reader system), comprises a reader box 100, which accepts a bead cell (or cuvette) 102 that holds the microbeads 8, having an embedded code therein. The reader box 100 interfaces along lines 103 with a known computer system 104. The reader box 100 interfaces with a stage position controller 112 and the controller 112 interfaces along a line 115 with the computer system 104 and a manual control device (or joy stick) 116 along a line 117. The reader interrogates the microbeads to determine the embedded code and/or the fluorescence level on the beads. The reader provides information similar to a bead flow cytometer but in a planar format, i.e., a virtual cytometer.