USB microscope

They generally offer a large depth of field and a range of magnification when examining the image on the computer.

USB microscopes are most useful when examining flat objects such as coins, printed circuit boards, or documents such as banknotes, but can be used on surfaces of irregular shape such as fibres owing to the high depth of field.

A common millimeter scale at the tops of the micrographs show the smaller size of the cubic table salt crystals.

Such devices are useful in forensic engineering where large fracture surfaces need direct examination, an application where conventional light microscopes are restricted in use.

Endoscopes with a small screen are also available, allowing the user to see the hidden scene directly without the use of a laptop computer.

Since this area of technology is still developing very rapidly, further design and technical improvements as well as lower prices may be expected in the near future (in February 2016, there were units costing less than $10 offered on internet sites).

Accessories such as polarizers are expensive but allow extra control of unwanted specular reflections from the subject, for example.