Glass Spheres, Borosilicate, 20 µm, SPI Supplies Uniform Microspheres, 1g
Nominal = 20µm
NIST Traceable = 19.9µm ± 1.4µm
Mean & C.V. = 1.8µm (9.0%)
Wt./pkg = 1 g
Approximate Count Per gm = 9.6 x 107
Small borosilicate glass microspheres have fewer spherical imperfections and inclusions than other glass microspheres. They also have better mechanical and thermal stability. This series has been calibrated with NIST traceable methods of optical microscopy. They are packaged as one gram of dry spheres (as a free-flowing dry powder). The borosilicate spheres have a density of 2.50-2.55g/cm3 and an index of refraction of 1.56 @ 589nm (23° C). For those interested in magnetic susceptibility measurements, such data does not (to our knowledge) publicly exist, but we can report that the only magnetism would come from the low level iron impurities, and which are not more than 0.2% by weight of Fe2O3. Furthermore, these borosilicate glass spheres have low levels of trace element impurities.
In addition to the numerous applications in microscopy, these borosilicate glass spheres can also be used for applications in flow tracing, filter checking, and instrument calibration.