Design of a Hollow Flexible Hinge for an Atmospheric Dispersion Corrector

Compliant mechanisms often have the advantage of high precision at the cost of a limited range of motion. In this research, a single Degree of Freedom hollow compliant hinge is developed for use in an Atmospheric Dispersion Corrector (ADC) found in the Extremely Large Telescope (ELT). The ADC contains two sets of optical prisms to correct for the unwanted dispersion effect that occurs when light meets the atmosphere at an angle. These prisms must perform a near-pure rotation around the optical axis, which must not be obstructed by the geometry of the ADC. This study strives to achieve the required deflection range while having sufficiently high unwanted eigenfrequencies, support stiffness, and low stress levels while bearing a relatively large load. The eigenfrequencies should be sufficiently high because of the vibrations originating from underlying systems in the ELT. This paper presents a comparison of various concepts, optimized with 3D nonlinear numerical finite element and multibody analysis software. Both high kinematic and dynamic performance is achieved through the addition of a kinematic coupler, or synchronizer. The existing concept adapted to the requirements of this work is called the Large Angle Flexure Pivot (LAFP), which is analyzed and expanded upon with a newly developed synchronizer to align with the requirements of the ADC.