【正文】 is m with the measurement conditions being: circular HS, downward stepping with Hz driving frequency. When the moving direction is changed to upward, the step size bees m due to gravity. In case of square HS, the downward and upward step sizes are and , respectively, which is more uniform because of its knife edge contacts with the sapphire rings. All these step sizes are rather large pared with other types of piezoelectric motors9,11,23 with the similar speed of motion is of course closely related to the driving frequency. The maximum driving frequency we set was 50 Hz, at which the speeds for the circular(upward versus downward) and square(upward versus downward)HS were:( versus )and( versus )mm/min.When the driving frequency increases or if the magnitude of the operating voltage drops, the step size diminishes as seen in Figs. 5 and 6. Although we get larger step size from circular HS, we still prefer the square HS owing to its advantages listed earlier. For instance, the travel range using the square HS is 9 mm(as designed)pared with mm for the circular HS(worse than the designed travel range).The performance curves of the square HS motor seen in are also smoother and more consistent than those ()of the circular HS motor. step size(left vertical axis)nd speed(right vertical axis of the motor using the circular HS as functions of (a) frequency(maximum operating voltage=177。200 V) and (b) maximum operating voltage (frequency=20 Hz).Although tested in room temperature, the motor has high potential to work in liquid helium temperature for two reasons:(1)its large step size can afford to pay for the thermal contraction still with remarkable step size remaining to produce a move。(2)its spring clamping structure validates the required friction relationship,|fr1|≈|fr2|≈|frbr|,in a very wide temperature range since a change from room temperature to liquid helium only shrinks the pression springs (～5 mm long, spring constant is about 286 N/m)by microns which do not considerably affect the pressing forces between the HS and the sapphire rings.The square HS may suffer wear and tear issues as its four edges could be scratched by the sapphire rings. To test its durability, we operated the motor repeatedly with 177。200 V and 50 Hz driving voltages for more than one thousand times with a displacement about 3 mm and the motor still worked well. The wear was not severe. Of course, the HS can be coated with wear resistant materials for better protection if necessary. step size(left vertical axis)nd speed(right vertical axis of the motor using the circular HS as functions of (a) frequency(maximum operating voltage=177。200 V) and (b) maximum operating voltage(frequency=20Hz).IV. CONCLUSIONWe have presented a powerful linear piezoelectric motor that owns several important features not simultaneously owned by other piezomotors,including: large step size,small size,very rigid,simple in structure and operation, very large temperature range, easy to make and loose machining tolerance,etc. Its durability has also been tested,which is rather these are highly desired in the construction of a modern SPM.ACKNOWLEDGMENTSThis work was supported by the National Natural Science Foundation of China under Grant ,the project of Chinese national high magnetic ?eld facilities,and Science Foundation of The Chinese Academy of Sciences under Grant No. YZ200846.,,and ,033704 2008.,and ,3806 1997.,4049 1992.,and ,113707 2008.,and ,2989 2001 ., Young quist, ,and ,2691 1998.,and ,26082004.,.:,514 2006.,and ,14591999.,1300 1997. and ,3552 2001.,,and ,093701 2005.,and ,Genes ,16272002.14Burleigh Instruments,Inc., ,902,084 1975. and Mrad,IEEE/ASME ,4272004.,and ,717 1999 . and ,IEEE/ASME ,441 2000. and , 2443,782 1995. and , 2190,520 1994.,and ,IEEE , 495 2002. and ,A 75,118 1999.,and ,1200 1989.,and ,IEEE Proceedings of the Fifth International Symposium on Mechatronics and Its Applications,2008 unpublished, –5.,International Patent Publication No. WO 93/19494 1993.,and ,536 2002.,and , 2593,801995.,,and , 346 2009.,and ,39091992.