Laser differential confocal measurement of the outer surface profile of a laser inertial confinement fusion capsule

A new laser differential confocal measurement method with a high axial resolution and insensitivity to surface inclination is proposed for high-precision measurement of the outer surface profile of a laser inertial confinement fusion (ICF) capsule. This method uses an eccentricity automatic adjustment system to rapidly adjust the capsule's centre to be aligned with the centreline of the rotary shaft. The capsule is then rotated by a high-precision rotation system, and the laser differential confocal measurement system (LDCS) radially measures the geometrical coordinates of each sampling point position in order to obtain the outer surface profile data of the ICF capsule. The proposed method achieves high-precision, non-contact, automatic, and rapid measurement of the outer surface profile of an ICF capsule. Theoretical analyses and preliminary experiments indicate that for the proposed method the measurement repeatability for the outer surface profile of an ICF capsule can reach 20 nm.