There are different types of diffusers, shapes, sizes, practically as many as there are fans of macro-extreme, being an instrument that lends itself to be customized with what you have on hand and according to the skills in DIY.
In this section I describe a diffuser dome provided by OGGLAB, allowing to illuminate specimens that have a size less than 10cm, a value already considerable.
The dome, printed with a 3D printer is composed of PETG resin (Polyethylene Terephthalate), which allows optimal light diffusion, has a good transmission, is resistant to UV and high temperatures. The printing was done with FDM (Fused Deposition Modelling) technique.
The height of the dome is 110mm, and a 65mm top hole allows easy access to large-diameter lenses. In case you want to maximize the reflective surface, you can insert a perforated disc of the diameter of the lens you use.
The dimensions of the base are 175mm (diameter), and the internal diameter is 145mm. The dome, in fact, has a double-wall, separated by one centimeter, allowing a better diffusion of light when illuminated by an external source (in my case two opposite LED panels).
The incident light rays are transmitted through the first semi-matt external layer and are further diffused by the inner wall, which acts as a sort of light source, as simplified in the following drawing.
Due to the position of the light source, I can’t obtain a complete homogeneous light diffusion (like the one obtained with the cylindrical system), but the tests carried out using two spheres as a sample (one in plastic material and one in metal) are encouraging. A third light and orientation of 120° between the sources give better results.
The test is done using two light sources located at about 10cm from the surface of the diffuser.
Using as a subject a small Coleoptera reveals the effectiveness; the following picture was acquired using an inverted Schneider-Componon 50mm/f2.8 lens, while the second below is a detail of the hind leg made using a Mitutoyo 20x lens. The second image turns out to be a little ‘flat’, probably having to play better with the position of the subject, but as a first result, I find it already interesting.
Otiorhynchus sulcatus (Curculionidae, Coleoptera). Mosaic of 2 stacks composed of 60 images each.
Otiorhynchus sulcatus (Curculionidae, Coleoptera) posterior leg with terminal hooks, and the characteristic setae. Image acquired with a Mitutoyo 20x, stack composed of 219 images. Acquisition time 1/3″, with step of 2µm between each photo.