I. Principles of laser ranging

Soga Laser Ranging Module

 consists of generating laser, laser receiver and voltage comparator. The laser receiver has a light filter, which receives reflected light emitted from the laser head, and outputs analog signal. The analog signal can be captured by MCU then has an AD conversion, it can also output digital signal via voltage comparator.

II. Applications

1. Ramp check

2. Obstacle avoidance

3. Safety production

4. Measuring distance

III. The advantages and disadvantages of laser ranging and ultrasonic ranging

1. Laser ranging is more accurate, even can be accurate to 1mm; ultrasonic ranging, only 1 cm

2. Laser ranging to measure distance can be hundreds or even thousands of meters, but the ultrasonic ranging only within 100 meters;

3. Laser ranging is more expensive than ultrasonic ranging

4. Laser ranging is susceptible to different environment, such as different reflectors.

IV. Problems

1. Because laser ranging is determined by the intensity of the reflected light, the impact of the color of reflector on the range is very large. From the experiment we found that black reflector’s dead zone is small and the measuring distance is small; while white reflector’s dead zone is relatively large, but the measuring distance is large.

2. We found that the brightness of the laser ranging module cannot be changed, so the measuring range is determined by the reflective surface color only. So we can connect a potentiometer in series inside laser circuit, by doing so, we can adjust the brightness of the laser, thus realizing using different colors for laser ranging for the same distance.

V. Results of the tests

From the results we can see that different shapes and colors of reflectors have different effects on test results.

From the test results we can see that the black reflector’s dead zone is less than the white reflector’s when under small distance. So in a conclusion, when we need to measure short distance, we use a black reflector; when we need to measure long distance, we use a white reflector. The range of this module is about 0.1m-4m.