An apparatus for the high throughput measurement of optical properties of liquid samples placed into the wells of a multiwell plate is disclosed. An optical fiber within a fiber bundle containing no corrective optics between the fiber ends and the well plate bottom illuminates the sample in order to induce fluorescence, and multiple fibers collect emission radiation and transmit it to a fluorescence detector such as a spectrometer. Other embodiments involve a light scattering illumination source with detection fibers located in either the same bundle containing the fluorescence monitoring fibers or an independent light scattering detection bundle for the measurement of static and/or dynamic light scattering. Some embodiments of the invention permit the measurement of phase analysis light scattering. Thus the measurement of multiple optical properties of a liquid sample may be made simultaneously or in succession. A method for these measurements is also disclosed.