By displacing the upper lens group (comprising of three lenses) along the optical axis
relative to the lower lying lens group, the actual working distance can easily be adjusted (see figure).
The problem is that still photography lenses are designed primarily for shooting still images, and therefore prone to focus shift and optical axis
shift while zooming, and so on.
provided by the number of Fresnel's zone; it can be predicted that when the system subtends an even number of Fresnel's zones the optical axis
will be dark and when this number is odd the same point will be bright Figure 2.
shift (image moves in the frame while zooming).
The PC NIKKOR series1 of lenses are lenses that support a shift function, with which the lens is moved parallel to the image plane, and a tilt function, with which the optical axis
is tilted in relation to the image plane.
The 19mm lens is equipped with lenses that support a shift function in which the optical axis
is moved parallel to the image plane.
The screen remains positioned on the optical axis
of the lens even when tilted, facilitating easy high-angle and low-angle shooting.
Performing posterior capsulotomy and anterior vitrectomy in the same surgical session as cataract extraction is effective in preventing PCO obscuring the optical axis
It might even be a laser mounted so its beam shines precisely down the optical axis
of the scope.
The spectrometer enables high-sensitivity ultra-trace elemental analysis, in liquids or on solid surfaces, to the parts-per-billion level, and combines a fully automatic optical axis
adjustment system that provides stable high-sensitivity analysis in a convenient benchtop form, according to the manufacturer.
Because the stage is designed to be supported from the bottom of the microscope near the optical axis
and incorporates steel cross roller guides, it is twice as stable and durable as conventional stages.
The optical axis
of the camera is rotated around the point O' by the angle [psi].