Fiber metal Laser Sensor And Its Application

When these rangefinders are used in material handling and industrial measurement applications, it is helpful to have a better understanding of distance laser sensors.

There are several configurations of laser sensors, some of which detect the presence, while others measure distance. Proximity laser sensors (also called laser photoelectric sensors) are commonly used to detect the presence of parts, but this is not the focus of this discussion. The focal point, visually and literally, is the laser distance sensor, which, as the name suggests, can measure distance.

These laser distance sensors use focused coherent light to measure the distance to the target object. In factory automation applications, the target is usually a product or machine element. They can detect any solid object and produce an output proportional to the measured distance, regardless of material, color, and brightness.

The high-resolution output provided by laser distance sensors is often used to provide position or displacement for the input of certain types of industrial controllers (such as PLCs). The output signal is usually highly accurate and includes temperature compensation to enhance stability.

There are several types of laser distance sensors, including diffuse, background suppression, and retroreflective. These sensors use CMOS or transit time technology to provide accurate distance measurement.

The laser must be focused and must be kept narrow over a long distance and narrow spectral range (light color). The emitted light can then be triangulated or pulsed, and each pulse returned to measure the distance reading.

CMOS technology is commonly used in short-range, high-precision laser sensors. The basic principle is to use a CMOS linear imager for optical triangulation. A diffuse triangulation laser distance sensor transmits laser light through a lens and reaches a target, which reflects light back to the sensor. The lens focuses the reflected light onto a small spot on the CMOS linear imager. The distance to the target object changes the angle of reflected light and the position of receiving light on the linear imager.

The measuring range of these CMOS diffusion triangulation laser distance sensors is about 1.5-60 cm. They are packaged in a small case of about 50mm x 50mm, with analog or discrete output, and usually work well regardless of the target material, color or brightness. These distance sensors have high resolution, in the low range (depending on the measurement range), the response time is less than one millisecond.

Class 1 lasers are eye-safe under all operating conditions. However, Class 2 lasers are safe, visible lasers that can be used for quick and unexpected observations of less than 0.25s, but if you stare intentionally, you may harm your eyes.

Time-of-flight technology is commonly used for long-range laser distance sensors, also known as rangefinder laser sensors. These types of sensors use a transmitter diode to generate a very short narrow-spectrum red or infrared pulse that is reflected from the target object and back to a sensitive laser energy detector, also known as a receiver diode. The precise electronics in the sensor can measure the propagation time of light and use the light speed constant to calculate the distance between the object and the sensor. The measurement range of the time-of-flight laser distance sensor is 1 cm to 100 m or more, and its size, output options, and laser sensing function are similar to CMOS sensors. These long-range sensors have good resolution, with an error of less than 2.5 cm from approximately 1 mm to 100 m at close range. In order to improve the measurement accuracy, multiple measurements are often made to reduce the response time of these devices to a few milliseconds.

Laser sensors usually work well in dirty environments because the focused light will "pass through" the dust. The focused beam can also achieve a longer sensing distance, and can detect small objects or targets through small openings.

Laser sensors are commonly used in process monitoring and closed-loop feedback control systems. Material handling is a common application that can be used to position cranes, gantry frames and automatic guided vehicles. Many other applications include component alignment, height measurement, robot positioning and welding head positioning.

Sometimes shiny or transparent objects can cause problems. Since the laser distance sensor can detect reflected light or straight-through beams, transparency and surface reflectivity can cause complications. Applications that require the laser to bounce off a shiny surface or see through a transparent surface should be carefully tested to ensure that the measurement can be performed as required. For example, it may be necessary to install the laser at a slight angle to the light-emitting surface, or adjust it to a lower intensity to correctly detect the light-emitting object, while it may be necessary to increase the intensity to burn through the transparent object.

Once the test is completed and any necessary adjustments are made, the laser sensor will operate in industrial applications for many years.