Large size aspherical optic surfaces have gained significant importance and indispensability because of their desirable
properties, and the fast growing demand needs urgently efficient and economical fabrication methods. A precision
diamond turning machine with rotating tool feed and fast tool servo systems special for turning large asphercial mirrors
is introduced, and a method to determine the best-fit sphere for this diamond turning method is also presented. A precise
in-site measurement of the processing optical mirror is planned to construct on this machine tool in order to enhance the
precision and efficiency, and reduce the production cost. The lateral shearing interferometer is known for being made
small and having almost common-path beams that makes insensitive to mechanical vibrations and air turbulence, so it
can be very suitable for measurement on the spot.
A precision rotating mode diamond turnimg method used for machining large optical asphercial elements is introduced.
The position errors between spindles of workpiece and cutting tool system are discussed, and error models of correctly
forming the aspherical reference sphere are set up. The constructed models are used in adjusting the machine for
ensuring the machining accuracy and efficiency.
To enhance the machining precision before polishing, 2-axis NC machining method is put forward for conic aspheric
optical mirror manufacturing. The integrated geometric model and the corresponding machining parameters, such as
suitable radius of tools, tool path interval, horizontal feed and axis feed are presented based on precision assurance for
lower manufacturing cost and higher production. The feasibility of the scheme and the reliability of the model are proved
with numerical examples by computer simulation. Therefore, it could provide a reference for NC control software system
in producing quadric optical mirrors and for other kinds of aspherical surface manufacture.
Demands on large off-axis aspheric mirrors with high precision have propelled innovations of new effective and economical fabrication techniques as well as ultra-precision machining systems. A new generation of forming method for large off-axis aspheric surface is introduced. Linear motion guides are employed in the tool feed systems on most of diamond turning machines. For a rotary spindle can be made easier and less expensive than a linear guide at the same accuracy level, especially in manufacturing of a large size component, a rotary arm that carries a diamond tool combined with fast tool servo is used to replace the straight line. Therefore a new structure of a rotary feed machine is developed. Combination of two rotating movement of workpiece and diamond tool, and the micro linear feed of the fast tool servo controlled by CNC system synchronously, ultra-precision large aspheric surfaces can be turned. The corresponding geometric models are presented based on constituting appropriate coordinate systems and giving equation of the off-axis aspheric surface. By computer simulation it is verified that the processing method for the large off-axis aspheric component is simple and feasible. According to the geometric models provided in this paper, the 3-D machining is achieved. This new fabrication method allows equipment investment be decreased.