Kinematic alignment structure for placement between components axially aligned in a cylindrical body

A kinematic alignment structure is provided for use as an attachment to a cylindrical body. The cylindrical body carries a plurality of axially aligned components, such as an optical lens barrel carrying a plurality of lens holders. The alignment structure includes a spacer ring having three support protrusions on each of the ring's two opposing surfaces. The spacer ring is rotatable around the axial direction of the lens barrel to position the support protrusions to control the axial alignment of the lens holders. The kinematic alignment structure also include a lens holder having a set of flexures around the outer circumference of the lens holder. The flexures are equi-angularly positioned on the outer circumference to adjust the lens holder in a radial direction and to facilitate assembling of the lens barrel.