Chotest SJ6000 Single-Frequency Laser Interferometer System for Precision Geometric Metrology

Overview

The Chotest SJ6000 is a high-precision, single-frequency laser interferometer system engineered for traceable, non-contact geometric metrology in industrial calibration laboratories, machine tool verification facilities, and advanced manufacturing R&D environments. It operates on the fundamental principle of optical interference—comparing the phase difference between a reference beam and a measurement beam reflected from a moving retroreflector—to derive displacement with sub-nanometer resolution. Its core design leverages a thermally stabilized He–Ne laser source (633 nm), servo-controlled frequency stabilization electronics, and high-bandwidth photodetection circuitry to achieve metrological integrity under dynamic conditions. The system conforms to the foundational principles of ISO 230-2 (determination of positioning accuracy of NC machines) and ISO 10360 (CMM acceptance and reverification), and supports compliance workflows aligned with ISO/IEC 17025 accredited calibration practices.

Key Features

• Single-frequency He–Ne laser source with active servo stabilization, delivering frequency stability of ±0.05 ppm—enabling long-term repeatability and minimizing drift-induced uncertainty.
• Nanometer-class linear resolution (0.001 µm) referenced directly to the SI-defined wavelength of 633 nm, eliminating reliance on mechanical scale artifacts.
• High-speed dynamic acquisition at up to 50 kHz sampling rate, supporting real-time analysis of motion profiles including velocity, acceleration, jerk, amplitude, and frequency content.
• Modular optical configuration: interchangeable retroreflectors, beam splitters, and angular/optical flats allow measurement of linear displacement, pitch/yaw/roll angles, straightness, flatness, perpendicularity, parallelism, and rotary axis errors.
• Integrated environmental compensation unit (temperature, pressure, humidity) compliant with Edlén equation implementation per ISO 10360-10 and NIST SP 958, enabling correction across ambient fluctuations without interrupting measurement continuity.
• Separate interferometer head and measurement mirror architecture minimizes thermal distortion coupling from host equipment, preserving optical alignment stability during extended thermal soak periods.

Sample Compatibility & Compliance

The SJ6000 is designed for use with standard kinematic mounts, precision granite tables, CNC machine tools (including multi-axis machining centers and coordinate measuring machines), and ultra-precision motion stages. It interfaces seamlessly with industry-standard motion controllers via TTL-compatible trigger signals (CT70 orthogonal trigger box optional). All measurement modes—including time-based dynamic capture and distance-triggered acquisition—support full auditability required under GLP and GMP-regulated environments. Data logs include timestamps, environmental sensor readings, instrument status flags, and operator metadata—facilitating 21 CFR Part 11-compliant electronic record retention when deployed with validated software configurations. Calibration certificates issued against NPL or NIST-traceable standards are available upon request.

Software & Data Management

The SJ6000 is operated through Chotest’s proprietary dynamic metrology software suite, which provides real-time visualization of displacement, velocity, and acceleration waveforms alongside FFT spectral analysis for vibration diagnostics. The software enables automated generation of error compensation tables (e.g., ball screw pitch error maps) in formats compatible with Fanuc, Siemens, and Heidenhain CNC controllers. All raw data is stored in binary-encoded .dat files with embedded metadata headers, supporting post-processing in MATLAB, Python (NumPy/Pandas), or third-party metrology platforms such as PC-DMIS or Q-DAS. Export options include CSV, XML, and PDF reports conforming to ISO/IEC 17025 reporting requirements—including uncertainty budgets calculated per GUM (JCGM 100:2008).

Applications

• Verification and periodic revalidation of CNC machine tool linear axis positioning accuracy, bidirectional repeatability, and volumetric error mapping per ISO 230-2 and ASME B5.54.
• Dynamic characterization of servo drive response, PID tuning validation, and resonance detection in high-speed feed systems.
• Rotary axis calibration—including angular positioning error, radial/axial motion error, and tilt coupling—using dual-axis angular optics and rotary encoder synchronization.
• Vibration monitoring during scanning applications where constant velocity—not absolute position—is critical (e.g., lithography stage control, optical surface profiling).
• Flatness and parallelism assessment of large-scale assembly surfaces using plane mirror and pentaprism configurations.
• Thermal deformation tracking of structural components under controlled environmental cycling, supported by synchronized temperature sensor input channels.

FAQ

What is the maximum unaided linear measurement range?
The SJ6000 achieves direct linear measurements up to 80 meters without auxiliary retroreflector extensions or vacuum-path configurations.
Does the system support automatic environmental compensation?
Yes—integrated sensors measure air temperature, barometric pressure, and relative humidity in real time, applying corrections per the modified Edlén equation as specified in ISO 10360-10.
Can the SJ6000 perform simultaneous multi-degree-of-freedom measurements?
While not fully simultaneous in hardware, sequential rapid-switching between linear, angular, and straightness optics—combined with synchronized trigger logic—enables correlated multi-parameter acquisition within a single experimental run.
Is the laser source certified for long-term stability and traceability?
The He–Ne laser module is factory-calibrated against national metrology institute references; its frequency stability (±0.05 ppm) is verified annually per ISO/IEC 17025-accredited procedures.
What file formats are supported for data export and integration with CNC controllers?
CSV and XML exports are natively supported; error compensation tables can be generated in Fanuc FANUC-MAP, Siemens SINUMERIK, and Heidenhain TNC formats.