Research On The Design And Installation And Calibration Technology Of White Light Interference Objective Lens With Large Field Of View

White light interference technology is based on wide-spectrum low-coherence vertical scanning measurement.It can measure the three-dimensional morphology of step element.Its detection range is limited by the field of view of the interference objective.At present,the splicing measurement was used to scheme to detect wide-field morphology of optoelectronic devices such as integrated circuits and microstructures.It is of great significance and value to develop a white-field interference objective lens.The paper developed a 0.5x wide field of view white light interference objective lens with a field of view of 60 mm and a working band of 450 ? 750 nm base on the Structural selection,theoretical design and calibration.It proposed a spectroscopic plate and a reference plate with an approximate Mirau interference structure base on the analysis of the existing interference objective lens structure.Due to its wide spectrum and difficulty in correcting aberrations,multiple pieces of calcium fluoride are used in the design of the optical system to correct secondary spectra and apochromatism.Tolerance analysis is performed using MTF and RMSSpot Radius as evaluation indicators and reasonable system tolerances are gived.The total length of the objective lens system is 297 mm,the minimum aperture of the optical element is 15 mm,the maximum aperture is 66 mm and the aperture size gradient is large,so it is difficult to process and assemble.Aiming at this problem,a three-stage clearance fit structure was proposed during the design of the mechanical structure,and the pitch,inclination and coaxiality requirements of the system were allocated to the mechanical components.The front group is the interference part,which assumes the function of adjusting the tilt of the objective lens.Pitch tilt is adjusted by pressure loop compensation.The middle and rear group is the imaging part,which assumes the function of objective lens center adjustment.Offcentring is adjusted by screw centering.During the installation,an active installation solution was proposed.The relative positions of each lens and its frame in the lens barrel were adjusted using screws.Besides,the project used the off-centre measurement system to measure so that make its camber angle within 3' required by the system.Finally,the project work ensure the consistency of the optical axis of the system,complete the installation and calibration and test the performance of the objective lens.