Fig. 1.

OPT design. The optical layout (A) and the corresponding CAD rendering (B) illustrate the detection (blue) and illumination (green) arms. A detailed view of the LEDs mount (C) demonstrates the system for alignment and switching. It is composed of a custom heat sink (yellow), a spring (red, C.254.250.0250.A, Vanel), and a ring (blue, SM1RR, Thorlabs) stacked inside a 1-inch tube (SM1L20, Thorlabs) and screwed to a quick-release translation mount (CXY1Q, Thorlabs). The custom sample holding mechanism (D) consists of a base tube (yellow) glued to a magnet (green) to hold the magnetic stainless steel cylinder (red). The sample is glued to the blue cylinder which can be screwed to the whole mechanism.