SOLS excitation

Adjusting light-sheet width

It is important to match the light-sheet width to the field of view (FOV) that is being imaged on the camera. This ensures the FOV is illuminated and that no light falls outside the FOV, which delivers unwanted photodose. This is easy achieved by adding an adjustable aperture in an intermediate image plane on the excitation path and matching it to the camera FOV:

A Gaussian laser beam with \(\frac{1}{e^2}\) waist \(w_{laser}\) can then be expanded on this axis to (for example) the full width 90% max for the FOV: \[ w_{laser} = \frac{FOV}{\sqrt{2\ln(10/9)}} \tag{1}\] or in terms of beam diameter \(d_{laser}\): \[ d_{laser} \approx 4.4 \; FOV \tag{2}\] Note: It is worth considering asymmetric expansion using cylindrical or Powell lenses to avoid high laser power losses. If the field aperture and expanded beam are in a magnified image plane (which they usually are), then this magnification factor should be taken into account when considering the size of the FOV (and therefore the size of the input laser beam).