A wafer alignment apparatus includes a light source, a light detection device, and a rotation device configured to rotate a wafer. The device further includes a diffuser plate through which a loosening fluid may be introduced into the swirl chamber. The pooling mechanism of the invention prevents a system from losing too many resources through the repeated making and breaking of excessive message queuing system connections. Then, the delay times of the delay circuits DLY1 to DLY5 are corrected based on the detection results of the reproduced sounds of the loudspeakers 6FL to 6WF.