Endoscopes with a small screen are also available, allowing the user to see the hidden scene directly without the use of a laptop computer. Alternatively, a simple USB device can be fitted to a conventional endoscope. As with the microscope, the cable is fitted with a USB plug to engage with the PC. Related devices include a USB endoscope, where the digital camera is fitted to a long length of cable and enables the camera to be used to inspect cavities which are otherwise difficult to examine (such as car engine interiors, pipe interiors, sewers and so on). They also find use in medical application such as ENT examinations. As they do not come into contact with the object viewed, sensitive crime scene evidence is not contaminated. USB microscopes are used in crime scene investigation units. They are normally handheld for this application, but can also be mounted in a small stand). Such devices are useful in forensic engineering where large fracture surfaces need direct examination, an application where conventional light microscopes are restricted in use. The good depth of field available is shown by USB micrographs of a sage leaf. A common millimeter scale at the tops of the micrographs show the smaller size of the cubic table salt crystals. Simple ways in which the microscope can be used is a comparison of salt crystals, such as sea salt and table salt. They are useful in examining large items in situ where use of a conventional microscope is impractical. USB microscopes are much less bulky than conventional stereo microscopes. Their use is generally similar to that of a reflection optical microscope or a stereo microscope. 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. The camera is usually sufficiently sensitive to generate an image with normal ambient lighting, without the need for an extra light source. They generally offer a large depth of field and a range of magnification when examining the image on the computer.

The camera is usually fitted with a light source, although extra sources (such as a fiber-optic light) can be used to highlight features of interest in the object. Images can be recorded and stored on a computer in the same way as with a webcam. Both still images and videos can be recorded on most systems. The quality of the final image depends on the lens and sensor quality, resolution-which may range from 1.3 megapixels to 5В MP or more-operator skill, and illumination quality. They usually provide modest magnifications (about 1Г— to 200Г—) without the need to use eyepieces, at cost very much lower than conventional stereomicroscopes. The camera attaches directly to the USB port of a computer without the need for an eyepiece, and the images are shown directly on the computer's display. The camera is usually sensitive enough not to need additional illumination beyond normal ambient lighting. In essence, a USB microscope is a webcam with a high-powered macro lens, and generally uses reflected rather than transmitted light, using built-in LED light sources surrounding the lens.

Their cost varies in the range of tens to thousands of dollars. They are widely available at low cost for use at home or in commerce. Microscopes essentially the same as USB models are also available with other interfaces either in addition to or instead of USB, such as via WiFi. The USB image of the underside of a sage leaf - more trichomes are visible on this side.ДЄ USB microscope is a low-powered digital microscope which connects to a computer's USB port.

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