Ratiometric range measuring, also known as ratio range finding or ratiometric distance sensing, is a technique used to measure distances or detect objects based on the ratio of reflected light intensities. This method is commonly employed in optical distance sensors, such as lidar (Light Detection and Ranging) systems, and works as follows:
1.Principle of Operation:
Ratiometric range measuring relies on the principle that the intensity of reflected light from an object varies with distance. As an object moves closer to the sensor, the reflected light intensity increases, and vice versa. By comparing the intensities of two or more reflected light signals, the sensor can determine the distance to the object.
2.Multiple Light Paths:
Ratiometric range sensors typically use multiple light paths or channels to capture reflected light signals. These channels may involve different wavelengths, polarization states, or angles of incidence to provide diverse information about the scene.
3.Reference Signal:
In ratiometric range measuring, a reference signal is often used as a baseline or standard against which the reflected light signals are compared. The reference signal may be generated internally by the sensor or provided externally by a calibration source.
4.Ratio Calculation:
The sensor calculates the ratio of the reflected light intensities from the object to the reference signal. This ratio is then used to estimate the distance to the object based on predetermined calibration curves or algorithms.
5.Distance Estimation:
By correlating the measured ratio with known distance-to-intensity relationships obtained during calibration, the sensor can estimate the distance to the object. This estimation may involve interpolation or curve fitting to determine the most probable distance value.
6.Output and Visualization:
The distance measurement obtained from ratiometric range sensing can be output in various formats, such as analog voltage, digital signal, or distance values. In lidar systems, distance information is often visualized as a point cloud or depth map representing the spatial distribution of objects in the scene.
7.Calibration and Optimization:
Accurate ratiometric distance sensing requires careful calibration and optimization of the sensor parameters, including the selection of appropriate reference signals, channel configurations, and data processing algorithms. Calibration ensures that the sensor provides reliable and consistent distance measurements across different operating conditions.
Ratiometric range measuring offers several advantages, including robustness to ambient light variations, immunity to surface reflectivity changes, and versatility in different environmental conditions. However, it requires precise calibration and signal processing techniques to achieve accurate distance measurements.
