MKS Instruments, Inc., a global provider of technologies that enable advanced processes and improve productivity, has announced the Ophir® PD300-MS microscope slide power meter for accurate measurements of light emitted from fluorescence microscopes. The PD300-MS measures power levels of high numerical aperture (NA) objectives, from 5µW to 1W. A special filter provides low angular dependence, enabling higher accuracy measurements. NIST-traceable calibration allows for measurement of wavelengths from 350nm to 1100nm. The power meter is designed for use with a wide range of light sources in such applications as photoactivation or photobleaching. To accommodate limited space, it has the same footprint as a standard microscope slide. The PD300-MS can be used at the sample plane in air or with water/oil immersion objectives without damage.