Development of a high-speed nanoprofiler using normal vector tracing method for high-accuracy mirrors

Three-dimensional surface figure measurement of high-accuracy spherical mirror with nanoprofiler using normal vector tracing method

“…Figure 5 shows the figure error in the Fizeau interferometer measurements (50.1-nm PV), and Figure 6 shows the results of the comparison. 12 Near the center, the two measurement results agree within ±5 nm, a result that can be attributed to factors relating to the differences in the spatial frequency and gap of the measurement ranges of the respective types of equipment, the precision of the nanoprofiler, and the systematic error of the phase-shift Fizeau interferometer. The estimated uncertainty due to assembly errors in the nanoprofiler by computer simulation is approximately 10 nm, whereas the estimated error in precision of the reference mirror of the phase-shift interferometer was similarly estimated to be approximately 10 nm.…”

“…Figure 4 shows the average figure error (44.9-nm PV) for the three measurements. 12 A standard deviation for each point of measurement was computed from each of the three measurement results, and the average value of standard deviations was used as an index of repeatability (0.6 nm). We could not achieve our repeatability goal of less than 0.2 nm because each measurement point was affected by recurring increases and decreases in scanning speed; it would be expected that improving the dynamic stiffness of the optical head would increase the repeatability.…”