With the progress of the biological sciences, the importance of observation of biological specimen, such as DNA or protein, has increased. It is one of the essential parts for this observation to get the microscopic images with nm resolution. For this purpose, the soft X-ray microscope is being researched and made. Soft X-ray microscope is generally composed of X-ray source, specimen, detector, and two optical components; condenser and objective. The main and most important role of the condenser is to be aligned to the position at which it can illuminate the specimen precisely and to be fixed at that position with low sensitivity to the disturbances from environment. The condenser especially needs to be aligned with 5-dof from which a rotation about the optic axis is excluded to get a satisfactory microscopic image. So the precision stage with more than 5-dof, nm resolution, and high stiffness is needed to align these components. The parallel mechanism is suitable for the high stiffness. But it is a rather hard work to make a parallel mechanism with 5-dof from which one rotation is excluded, and the precision stage with 6-dof is studies for several decades much more than that with 5-dof. In this paper, therefore, the precision stage with 6-dof, nm resolution, and high stiffness is proposed.
A typical example of the precision stage with 6-dof is Stewart Platform, which is first proposed by D. Stewart in 1965. The fixed base plate and the moving platform in Stewart Platform are generally connected with 6 struts, ball joints and/or universal joints. But these kinds of joint have always clearance and backlash that make impossible to achieve nm resolution of the stage.
In this paper, a new kind of flexible joint and Stewart platform using this joint is proposed. The modeling and optimal design of Stewart platform using flexible joint, and the experimental results are also presented.