which scientist used a simple light microscope and saw microorganisms in pond water?

The scientist who used a simple light microscope and first observed microorganisms in pond water was Antonie van Leeuwenhoek. In the late 17th century, he used a microscope of his own design to study water samples and became the first person to document the existence of microscopic organisms, which he referred to as “animalcules.” His observations were groundbreaking in the field of microbiology.