Meetoculair 12,5x met Walton & Beckett graticule
Standard oculair 12,5x met Walton & Beckett graticule
- Diametre: 23,2 or 30mm
- Vergroting: 12,5
The Walton and Beckett reticle is used for counting fibrous dust (e.g. asbestos or glass fibers) and is particularly useful where the majority of fibers to be counted are shorter than 5 µm. The circle is divided into four by two diametrical lines scaled in units of 5 and 3 µm respectively. It turns out that 3 and 5 µm are the critical measurements of fiber lengths and diameter used in fiber counting. Unlike the usual globes of other particle reticles, the Walton and Beckett has a series of shapes to which analyzed features can be compared. The shapes have been carefully designed for direct comparison with fibers.
(G24 Walton & Beckett for asbestos)
