The unit is installed on the left emission port of the microscope. The excitation light passes through the dichroic filter, the scanning mirrors and the lens before entering the microscope; the fluorescence light follows the same path: from the microscope it passes through the descanning lens, the mirrors and it is finally reflected by the dichroic in a direction perpendicular to the excitation.

A peculiarity of the unit is in the way the dichroic if utilized: the excitation light traverses the dichroic whose transmission is around 80-90%; the fluorescence instead is reflected. In so doing the losses of fluorescence light are minimized. The scanning mirrors provide great distortion-free images on an area of about 100 µm diameter. More importantly, they can be stopped at any XY location with no jitter, a condition required for the acquisition of FCS data.

For z-stack applications the scanning mirrors unit is used in conjunction with a z-axis piezo control of the objective.

Descanning lens
The descanning lens is key component of the scanning mirrors unit. It is a high aperture laser objective achromatic system (f=60 mm, NA=0.19) made of a cemented achromat and aplanatic meniscus lens with a 40 mm diameter. The lens features an anti-reflection ARB2-line coating (see Figure 6).

Scanning mirrors controller
The control electronics of the scanning mirrors unit is housed in a separate unit, which communicates to the computer through the USB communication port.

Mechanical

Electrical, Drive Armature

Electrical, Position Detector