Customers kept telling the engineers at Banner Engineering that they needed to sense objects at greater distances than the inches to feet possible with existing photoelectric and laser sensors; for example, "seeing" out to 10-15 feet in a steel mill so that any electronics could survive the heat. Now, thanks to advances in telecommunications and home entertainment, they can measure accurately out to 50m (164 ft).
Just how did these twin technologies come together, resulting in a position sensor? "The advent of high-speed, clean amplifiers in cell phones was needed to handle GHz signals," says Mike Dean, Banner engineer and technical marketing manager. "And computer makers went from CD to DVD drives, which brought about low-cost, visible lasers with a finer spot size (shorter wavelength)."
Using such microcircuits and laser, the L-GAGEģ LT3 Time-of-Flight compact laser sensor (2.7 ◊ 1.38 ◊ 3.39 inches) senses out to 50m in its retro-reflective model. Its small size, incorporating surface mount components and more efficient power supplies, along with no need for a separate controller, conserve space and decrease set-up time. And its price starts at $845.
The Class 2 laser device features analog and discrete outputs with independently configurable setpoints. With a single button, a user can configure the sensor. Other LT3 versions sense gray targets from 0.3-3m (1-9.8 ft) and white targets 0.3-5m (1-16.4 ft) away. Resolution can be 1 mm (0.04 inch) depending on response speed, (1, 10, or 100 msec).
Users are also able to set the size and position of a "sensing window" (upper and lower range limits) or program a set-point threshold within a 1m window. Analog output is either 4-20 mA or 0-10V dc. The LT3 can be remotely programmed. Circuit design protects the sensor from reverse polarity and transient voltages and the ABS/polycarbonate housing helps provide an IP67 NEMA 6 rated enclosure.