Sensor Offers Spin on Conventional Time-of-Flight Imaging

A time-of-flight (ToF) sensor developed by technology company Toppan and its Shizuoka University-spinoff subsidiary Brookman Technology uses a short-pulse modulation method to enable distance calculation up to 20 m in high brightness conditions and up to 30 m in indoor lighting conditions. The technology is expected to extend the practical use of image sensors and cameras for autonomous drones and other industrial applications, the companies said.

Prototype of the ToF sensor camera developed by Toppan and Brookman Technology. Courtesy of Toppan Inc.

To tackle high brightness conditions, each pixel of the CMOS image sensor is equipped with a function to eliminate components of external light. The device is able to measure distances up to 20 m under illuminance conditions of 100,0000 lux, equivalent to daylight conditions in midsummer.

The sensors achieve a range more than 5× what is possible with sensors using the conventional indirect ToF method. The collaborators refined Brookman Technology’s short-pulse modulation method to realize the hybrid ToF technique. Short-pulse modulation measures distances by emitting pulses of light with an extremely short duration. It contrasts continuous-wave modulation, in which continuous waves of light are emitted.