Laser Displacement Sensor - Displacement Sensors

Laser Displacement Sensor

The principle of laser displacement sensor ranging

The principle of laser displacement sensor ranging is a method where triangulation is applied by combining the emitting element and the position sensitive device (PSD) to perform ranging (detecting the amount of displacement).

The emitting element of Panasonic Industrial Devices SUNX's laser displacement sensors uses a semi-conductor laser. The laser light is focused through the emitting lens and projected on an object. At that time, some of the light beam that is reflected from the object produces a light spot on the position sensing device. When the object moves, the PSD moves as well. Detecting the changes in positions makes it possible to detect the amount of displacement of the object.

Some of the receiving elements use a linear image sensor, and not the PSD. The PSD enables you to acquire information only about the center position of the amount of light of the entire light spot. On the other hand, the emitting elements with the linear image sensor detect the amount of light received by each cell. Therefore, even when there are variations in the amount of light within the spot due to influences from the object's surface, even more accurate detection can be performed for the peak position of the light intensity. This significantly reduces errors due to the influence of the objects' surfaces.

Principle : For detection of a V-shaped groove

<Linear image sensor method>

As the sensor measures the peak position of the light spot, it is not affected by secondary reflected light, resulting in no error.

<PSD method>

As the sensor measures the center of gravity for the light quantity distribution of the entire beam spot as position information, errors occur due to the presence of secondary reflected light.

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Non-contact detection

Detects an object without contact.
Non-contact sensing ensures longer life for the sensor and absolutely no damage to the object.

Short response time

The use of an optical beam for detection and complete electronic circuitry makes the sensors respond so quickly that they can be easily used on a high-speed production line.

High accuracy detection

Advanced optical system and electronic circuit technology have achieved a sensing accuracy of up to 0.01 μm 0.0004 mil (HL-C2 series).

Detection according to workpieces

Stable detection is possible by using the minute spot light for minute objects, such as IC pins, and the line spot light for diffusely reflecting surfaces, such as cutting surfaces.

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Effective use of the laser displacement sensors

When there are variations in materials and colors

When performing a displacement measurement of a moving object that has significantly different materials and colors, errors can be reduced to a minimum by mounting the sensor as shown below.

Measurement in a narrow space or a depressed portion

When performing a displacement measurement in a narrow space or in a hole, mount the sensor so that the light route from the emitting parts to the receiving parts will not be interrupted.

Measurement of rolling objects

When measuring a rolling object, mount the sensor as shown below. It can reduce influences such as downward / upward fluctuations and displacement.

Measurement of black objects or objects that reflect little light

When performing a displacement measurement on black objects that reflect little light, the resolution becomes lower. This is because the amount of light is reduced at the receiving part and the signal received from the PSD becomes small. In such a case, mount the sensor as shown below in order to increase the amount of light received.

<For specular reflection>

Mounting the sensor this way increases the amount of light received by receiving specular reflective light which is a greater amount of reflected light.

<Bringing the sensor close to an sensing object>

The amount of light received is in inverse proportion to the squared distance between the sensor and an object. When shortening the distance, the amount of light received increases.

When objects have an uneven surface

When a moving object has an uneven surface, mount the sensor as shown below in order to reduce the influence of step edges when measuring the object.

When mounting the sensor head to the wall

Mount the sensor as shown below in order to prevent multiple reflective light rays from entering into the receiving part on the wall. In addition, in the case that the reflective rate of the wall is high, using a non-glossy black wall is effective.

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Related Products


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