finesse.components.lens.Lens.actuate_f

Lens.actuate_f(dioptres, direction=('x', 'y'))

Actuate on the focal length of the lens with a specified dioptre shift.

Sets the focal length to a new value, \(f_2\), via,

\[f_2 = \frac{1}{d + \frac{1}{f_1}},\]

where \(f_1\) is the current focal length and \(d\) is the dioptre shift (i.e. the dioptre argument).

By default, both focal planes are shifted. To shift, e.g., only the tangential plane, specify direction="x".

Parameters:

dioptresfloat

Shift in lens focal length in dioptres.

directiontuple or str, optional; default: (“x”, “y”)

Focal plane to shift, defaults to both tangential and sagittal.