Here you can see the setup for optical preview of the sample. The preview was intended to be placed on a optical bench. The main objective was to make it quite compact and easy to use (no need to adjust anything between uses).

The setup uses mostly thorlabs 30 mm cage system, but there are also a few elements that I had to order on our faculty's mechanical workshop (shown above in red). The setup comprises of:

• thorlabs cube mounted pelicle (CM1-BP108)
• thorlabs cube with polca-dot beamsplitter
• thorlabs cube connector (CM1-CC)
• 4 x thorlabs assembly rod (ER4-P4)
• a short lens with a mount
• thorlabs cage plate (CM02/M)
• thorlabs adapter plate for optical fiber (SM1FC)
• optical fiber connected to a white light source
• ccd camera with infinity adjusted objective
• custom made mount for the bottom cube (to turn it 90 degrees)
• custom made mount to connect the CCD camera to the upper cube

Below you can see the testing phase of the setup: no custom parts and a second pelicle instead of a polca dot. It is a proof of concept and works well. However the second pelicle reflects very little light and a polca dot is needed to shine more light on the samples surface (and therfore to better see the sample surface).

Why would you even want to use such a setup? Imagine that you are investigating small features on the sample, like a micropillar (SEM micrograph shown below) or a very small flake of some dichalcogenides. You would like to focus laser on such an object.

The problem is that it is very hard to find such features on the sample. Below is placed a SEM micrograph of the sample with micropillars). Without the preview setup it is virtually imposible to find the micropillars during measurements...

Finally, below you can see the image as seen by a ccd camera of the preview setup. Here you can see a 10-um micropillar with a green laser spot over it. As you can see, finding your micropillar is not that hard anymore.