Laser interferometry measurement technology has the advantages of high sensitivity, large range, and adaptability to harsh environments. Light waves can directly define meters and are easy to trace. The PLR3000 series fiber laser ruler independently developed by Zhongtu Instrument is based on the principle of laser interferometry measurement. It is an advanced position detection device with high precision, high sensitivity, and high efficiency and speed. It has advantages in non-contact high-precision measurement field. Compared with traditional steel tape rulers or glass gratings, it has more accurate grid spacing and higher resolution. At the same time, its heat source isolation design ensures higher stability. It also has the characteristics of fast installation and easy collimation. It is widely used in modern ultra precision manufacturing, photolithography technology, aerospace and other high-tech fields such as microelectronics, micro mechanics, and micro optics.

Composition of fiber laser ruler

The fiber laser ruler consists of a laser emitting device, an interferometric probe, a reflecting mirror, and other components.

1. Laser emission device

The laser emitting device is equipped with a high stability helium neon laser light source, with a frequency stabilization accuracy of 0.05ppm (optional 0.02ppm). The laser is transmitted to the interferometric measurement probe through armored optical fibers, achieving isolation between the heat source and the measurement probe. The laser emitting device is equipped with a high-precision signal processing system, which can directly output real-time RS422 digital orthogonal signals and orthogonal analog signals with user configurable resolution. It can also be further developed through USB-SDK.

2. Interference measurement probe

2.1. Differential Interference (DI) Probe

The differential interference probe outputs two laser beams (reference light and measurement light), which are respectively reflected by a fixed plane mirror and a moving plane mirror to achieve optical fourth harmonic generation, with higher system resolution and smaller nonlinear errors. Especially suitable for measuring the relative motion between Z-axis columns and motion platforms, eliminating errors caused by inner wall thermal drift and column vibration/movement, it is the choice of nanometer level precision solutions.

2.2. Plane Mirror Interference (PI) Probe

The planar mirror interference probe adopts a dual path interference system, combined with a planar reflector, to achieve optical fourth harmonic generation with higher system resolution. It uses a dual axis system and a long strip planar reflector, which is particularly suitable for XY platform motion control and measurement applications. Provide two light output configurations: 0 ° and 90 °.

2.3. Cone Prism Interference (RI) Probe

The conical prism interference probe is easy to install and has high accuracy. It is suitable for single axis linear measurement or position feedback, with a measurement distance of up to 10 meters and can be customized to 40 meters. It is widely used in motion positioning and equipment calibration. Provide two light output configurations: 0 ° and 90 °.

Technical characteristics of fiber laser ruler

1. High precision measurement: Linear measurement accuracy can reach 0.5ppm;

2. High laser frequency stability accuracy: The laser frequency stability reaches 0.05ppm (optional 0.02ppm)

3. High resolution: The inherent resolution can reach up to 10nm, and different resolutions can be configured to further expand segmentation and achieve higher resolution.

4. High speed measurement: The maximum measurement speed can reach over 2000mm/s;

5. Long measurement range: The measurement range can reach 4m or more, and can be customized to 40 meters;

6. Easy to install and align: compact size, flexible installation, can significantly reduce Abbe error; The interference probe is equipped with an angle adjustment device, making it easy to achieve beam collimation;

7. Measurement of optical path heat source isolation: The laser emitting device is separated from the measurement probe, and the probe has no heat source, which can avoid the influence of host heat dissipation on the measurement path;

8. Multi channel output: Up to three probes can be connected simultaneously, making it easy to measure multiple axes and degrees of freedom simultaneously;

9. Diverse output interfaces: The host output interface includes USB interface and position output interface. The position output interface includes differential TTL (RS-422/EA-422), sine cosine signal (SinCos1Vpp), and USB-SDK.

Application verification of fiber laser ruler

The PLR3000 series fiber laser ruler has been validated for accuracy on multiple clients: using differential interference (DI) probes for closed-loop control of high-precision nanodisplacement tables, achieving nanometer level position control accuracy at any position within a 10mm stroke.