Position detection method for microwell chip on microscope stage by photon multiplier tube

In this paper, we propose a position detection method for a microwell with manageable volume (MMV) chip on the stage of the inverted microscope. When the manipulation robot arm puts an MMV chip on the microscope stage, there is alignment error up to 500 μm. This error affects measurement accuracy of fluorescence from solution filled in a tiny hall of the MMV chip. Usually, CCD image processing is used for detecting a position. However, appending a CCD camera to our microscope increases the complexity of the optical system. Therefore, we used a photon multiplier tube which was already equipped for measuring fluorescence. In the result, the position of the MMV chips was detected by putting a pilot LED directly above the objective lens. The detection error was less than 10 μm. Although this method was devised for our system, we considered that it was available in other micro optics systems.