Tree-D Model T261 High Speed Laser Scanning Sensor

The Tree-D T261 non-contact laser-based scanning sensor uses optical triangulation in a unique optical configuration using a bright laser spot and a high signal-to-ambient light level ratio. This allows operation in full sunlight. Unlike some triangulation type sensors, the T261 uses a narrow included angle between the laser and the measuring camera. This included angle has been optimized as a trade off between ease of application and the accuracy required for adequate scanning of logs at high speed. A patent has been applied for in this configuration. Accuracies of ±0.005” are achieved depending on working distance.

Conventional “light shear” scanning systems use laser line generator optics to spread the laser energy out over a line. The Model T261 scans a single, bright laser spot across the surface. Using a single moving mirror, a line scan imager tracks the laser spot. This produces laser intensity at any given surface point tens to hundreds of times brighter than if it were spread out over a long line.

The T261 contains its own temperature control system, maintaining the laser and sensor circuitry temperature to narrowly defined range. This ability to regulate internal temperature maintains high sensor accuracy over the entire working temperature range.

The scanning mirror is driven at about 36Hz, which produces 72 scans per second (one up scan and one down scan). This results in one scan per inch of motion when scanning an object moving thru the scanning system at 360 feet per minute. Each T261 sensor contains an advanced RISC architecture microcontroller that communicates to a data Concentrator Computer through a high-speed serial connection. This microcontroller acquires distance measurement samples thousands of times per second. These data are then translated into X and Y coordinates representing the surface of the object being scanned. These coordinates are buffered on the Concentrator Computer and made available as a server process over Ethernet.