To return the reflected beam from the surface to the center of the QPD, each stage of the optical system is follow-up controlled. Ultimately,

the normal vectors are acquired by each goniometer. Figure 3 Photograph of newly developed nanoprofiler. Figure 4 A schematic view of a nanoprofiler based on normal vector measurements. Figure 5 shows the five-axis simultaneous control system, which consists of an optical system and a sample system. The optical system has NVP-LDE225 clinical trial two rotational motions and one linear motion, which is follow-up controlled to trace the normal vectors. The sample system has two rotational motions, which are fixed-command controlled. This zero method in which the incident and reflected light paths are made to coincide avoids the effects of differences selleck products in QPD sensitivity and changes in the refractive index distribution. In fact, the stationary errors of normal vector tracing are larger than the target accuracy, so the QPD signal is read simultaneously with the output from the five-axis encoder. Consequently, the stationary errors can be ignored, and this process can be treated as the zero method. Figure 5 Block-diagram of five-axis simultaneously controlling system. The optical system with two rotational stages and one linear motion stage

is follow-up controlled to trace normal vectors, while the sample system with two rotational stages is fixed-command controlled. Measurement of a Non-specific serine/threonine protein kinase concave spherical mirror with 400 mm radius of curvature We measured a concave spherical mirror with a 400 mm radius of curvature three times. The measurement time was 25 min. The optical system, i.e., the light source and QPD, was set at a point of 400 mm from the center of the mirror. When measuring a concave spherical mirror, if the optical system is set at the mirror’s center of curvature, we do not need to move the sample system, and the reflected beam returns to the QPD within its dynamic range.

Therefore, we can acquire normal vectors from the QPD output signal. Figure 6 shows the average figure error for the three measurements, which is 70.5 nm PV. Next, we evaluated the repeatability. The repeatability is evaluated by taking the average of the shape error for three times, and finding a difference from the average. Figure 7 shows the first-time repeatability of our profiler. The repeatability was greater than 1 nm PV for all three measurements, as given in Table 1. Figure 6 Figure error for concave spherical mirror (average of three measurements). Figure 7 First-time repeatability for concave spherical mirror. Table 1 Repeatability results for concave spherical mirror   First Second Third Repeatability PV 0.81 nm PV 0.74 nm PV 0.85 nm We can reduce random errors such as air flow and drift in temperature fluctuations by controlling the temperature, provided that we can further stabilize the constant-temperature room.