In addition, we compared the results for the concave spherical mirror with those obtained using a Fizeau interferometer, as shown in Figures 8 and 9. The result for the Fizeau interferometer is 70.0 nm PV. Table 2 Selleck Entospletinib summarizes the results for both the profilers. Figure 8 Fizeau interferometer results for concave spherical mirror in three dimensions. Figure 9 Fizeau interferometer results for concave spherical mirror in two dimensions. Table 2 Results of nanoprofiler and Fizeau interferometer for concave spherical mirror   Nanoprofiler Fizeau interferometer In three dimensions PV 70.5 nm PV 70.0 nm In two dimensions PV 40.0 nm PV 45.0 nm Measurement range 20 × 20 mm 30 × 30 mm The difference between

the nanoprofiler and Fizeau interferometer results for the figure error may depend on each device’s system error. On the other hand, the phase-shift Fizeau interferometer is affected by the precision of the reference

mirror. We cannot conclude that the difference in these results is caused only by the greater precision of the nanoprofiler. Therefore, Selleckchem R406 we conclude that the profiles of both the mirrors are consistent within the range of systematic error. Measurement of a flat mirror We measured a flat mirror three times. The measurement time was 20 min. When measuring a flat mirror, we need to move the sample system which has two sets of two pairs of goniometers, optical system which has two sets of two pairs of P5091 order goniometers and one straight stage, and the reflected beam returns to the QPD within its dynamic range. During the measurement, each axis is controlled numerically. The numerical control parameter is calculated in advance from the ideal shape of the sample. We detect the gap in the normal vector for the figure error using QPD because the sample has a figure

error. Therefore, we can acquire the declination of the normal vectors from the QPD output signal. Figure 10 shows the average figure error for the three measurements, which is 21.0 nm. Next, we evaluated the repeatability of the measurements, as shown in Figures 11, 12, and 13. The repeatability of the first, second, and third measurements was 1.08 selleckchem nm PV, 1.26 nm PV, and 1.25 nm PV, respectively. Figure 10 Figure error for flat mirror (average of three measurements). Figure 11 Repeatability for flat mirror (first time). Figure 12 Repeatability for flat mirror (second time). Figure 13 Repeatability for flat mirror (third time). When we compare the repeatability results, we see that the repeatability in each direction varies depending on the measurement. Because we used a raster scan method for these measurements, the acceleration and deceleration provided a rigorous method of measurement. Therefore, every measurement point is slightly different. The repeatability is expected to be enhanced by improving the dynamic stiffness of the optical head. In addition, when we measure a flat mirror, five axles are controlled and moved.