Nanometer level freeform surface measurements with the NANOMEFOS non-contact measurement machine
conference paper
Applying aspherical and freeform optics in high-end optical systems can improve system performance while decreasing the system mass, size and number of required components. The NANOMEFOS measurement machine is capable of universal non-contact and fast measurement of aspherical and freeform optics up to Ø500 mm, with an uncertainty of 30 nm (2σ). In this machine, the surface is placed on a continuously rotating air bearing spindle, while a specially developed optical probe is positioned over it by a motion system. A separate metrology system measures the probe and product position relative to a metrology frame. The prototype realization, including custom electronics and software, has been completed. The noise level at standstill is 0.88 nm rms. A reference flat was measured with 13 μm and 0.73 mm tilt. Both measurements show an rms flatness of about 8 nm rms, which correspond to the NMi measurement. A hemisphere has also been measured up to 50° slope, and placed 0.2 mm eccentric on the spindle. These measurements reproduce to about 5 nm rms. Calibration and software are currently being improved and the machine is applied in TNO aspherical and freeform optics production. © 2009 SPIE.
Topics
TNO Identifier
242588
ISSN
0277786X
ISBN
9780819477163
Article nr.
742606
Source title
Optical Manufacturing and Testing VIII, 4 August 2009 through 5 August 2009, San Diego, CA
Editor(s)
Burge, J.H.
Fähnle, O.W.
Williamson, R.
Fähnle, O.W.
Williamson, R.