Method and apparatus for measuring rotational speed of satellite disk on MOCVD planetary susceptor

A method for measuring a rotational speed of a satellite disk on a MOCVD planetary susceptor, comprising following steps:

• emitting a beam of laser light from laser detection probe (1) on an MOCVD equipment;
• irradiating the laser light on a planetary susceptor (6) of the MOCVD equipment, and as the planetary susceptor (6) revolves, the laser light also irradiating on a satellite disk (7) and wafers (8) on the satellite disk (7);
• splitting and converting reflected laser light into an electrical signal;
• sampling the electrical signal at a fixed frequency f within a time period of two trigger pulse signals (9) to obtain an angle Aa revolved by the planetary susceptor (6) for each sampling;
• in reference to the angle Δα, calculating a rotation angle φ0 of the satellite disk at a moment when an edge of a wafer (8) enters a viewport;
• in reference to the angle Δα, calculating a rotation angle φ1 of the satellite disk at a moment when the edge of the same wafer (8) leaves the viewport;
• and
• obtaining a rotational speed of the satellite disk (7) by calculating variation between the rotation angle φ0 and the rotation angle φ1.