Borescopes $30–$ 130+
You don’t have to be a doctor to benefit from tools that see where the sun don’t shine. Borescopes are mandatory for inspecting the insides of jet engines, turbines, and other machinery without disassembly, but they are also put to work in all kinds of buildings, from peering into cavity walls to examining inside pipe welds.
Basically a light-transmitting tube with a lens at one end
(which forms the image) and an eyepiece at the other (to enlarge the image), borescopes were perfected during World War II for inspecting cannon bores—hence the name. (Endoscopes are their medical cousins.) The technology has become so convenient of late that borescope-type gadgets are hawked on late-night TV for homeowners who want to snoop behind kitchen cabinets or down sink drains. RIGID BORESCOPES, the simplest type, mount the lens and eyepiece on a stiff tube. While not as versatile as other types—the subject of inspection must be in a straight line from the viewer—they do offer a higher quality image at a lower cost. In industry, rigid borescopes find most use in inspecting automotive cylinders and in gunsmithing.
FLEXIBLE BORESCOPES (aka flexscopes) replace the rigid tube with a fiber-optic bundle that conducts light between lens and eyepiece. This bundle allows the scope to articulate around bends, but the tradeoff is image quality, which can be prone to distortion such as pixelation from the individual fibers or crosstalk between them. The quality and clarity of the image also depends upon the number of fibers. More fibers and larger tube diameter equals better resolution and quality; 10,000 pixels is generally considered the minimum, with the best in a range of 15,000 to 22,000 pixels. The bundle also includes fibers that control lighting for the target. Flexible borescopes perform all kinds of building inspections: wall cavities; ceiling, roof, and floor voids; HVAC ducts; boiler flues and sewer lines.
VIDEO BORESCOPES (aka inspection cameras) upgrade the optics of a flexible borescope with a miniature, real-time camera. These are typically based on CCD (charged coupled device) sensors, the same used in digital and video cameras. The larger the CCD, the more light it can capture, so the better the resolution and image detail, but at greater expense. Sensors based on CMOS (complementary metal oxide semiconductor) technology are less costly to produce, and have made video borescopes affordable even at the consumer level. No surprise, video units are the most expensive borescopes of the lot—typically several hundred dollars, but prices drop every year. As with thermal imaging, some of today’s borescopes send images to a smartphone for recording or further transmission.