Comprehensive Application of Vision Measuring Machine in Precision Dimensional Inspection of Prism Bases for Laser Interferometers

In precision optical instrument systems such as laser interferometers, the prism base serves as the "skeleton" that positions and holds the prism. Its structure typically includes complex features such as inner/outer diameters, multiple mounting holes, locating slots, stepped surfaces, and irregular contours. The machining accuracy of the prism base directly determines the collimation stability and repeatability of the optical path system.

For manufacturers of prism bases, even a micron-level dimensional error can cause measurement drift and poor repeatability in laser interferometers. Therefore, achieving comprehensive and efficient inspection of key geometric dimensions has become a common challenge in the industry.

I. Industry Pain Points in Prism Base Inspection

Prism bases are usually made of metals (e.g., aluminum alloy, stainless steel) or precision ceramics, with the following typical characteristics:

• Multiple dimensional features intersect: Inner/outer holes, threaded holes, mounting hole spacing, locating holes, stepped surfaces, irregular contours — all need to be evaluated under the same datum.
• Extremely tight tolerances: Laser interferometers require micron-level flatness, hole position tolerance, diameter tolerance, and perpendicularity for prism bases.
• Large batch sizes and many inspection items: Dozens of parameters must be checked per batch; traditional methods often miss critical dimensions.
• Large human measurement errors: Calipers, height gauges, and micrometers rely on manual reading and recording, making consistency and traceability difficult, leading to undetected batch defects.

These long-standing problems urgently require a higher-precision, more efficient, and traceable inspection solution.

II. What Can SIG Vision Measuring Machine Measure?

For all geometric features of prism bases, the SIG fully automatic Vision Measuring Machine comprehensively covers the following inspection items:

1. Hole Diameter and Hole Group Position Tolerance

The inner/outer hole diameters directly affect the fit tightness of prism installation. SIG Vision Measuring Machine accurately measures the diameter, ovality, and radial deviation of each hole. For multiple mounting holes, it measures all center distances in one click and automatically calculates position tolerance of the hole group, effectively preventing optical axis misalignment caused by hole position deviation. Measurement accuracy reaches micron level, with repeatability within +/-1.5μm.

2. Flatness and Parallelism Measurement

The flatness of the mounting surface and the parallelism between top and bottom surfaces are critical for repeatable positioning accuracy of laser interferometers. SIG Vision Measuring Machine performs full-field Z-axis height scanning to generate a flatness deviation distribution map, identifying high and low points to support subsequent grinding or process adjustments. Equipped with high-precision glass scales (resolution 0.1μm) and an autofocus system, it quickly evaluates flatness across the entire base surface.

3. Perpendicularity and Angle Detection

Prism bases often include stepped surfaces, locating slots, and mounting posts. The angles and perpendicularity between these features directly influence the optical path. SIG Vision Measuring Machine supports automatic measurement of perpendicularity, angle, and inclination tolerances. Using high-resolution CCD imaging and sub-pixel edge extraction algorithms, it calculates angular deviations between datum and measured surfaces under non-contact conditions — especially suitable for internal perpendicularity of small holes, which cannot be measured by calipers.

4. Irregular Contour Dimension Measurement

Prism bases often have irregular edges, curved steps, and guide slots. Traditional calipers or projectors cannot accurately fit these non-standard contours. SIG Vision Measuring Machine has built-in powerful geometric element construction tools, supporting automatic recognition and measurement of points, lines, circles, arcs, rectangles, slots, rings, open curves, closed curves, etc., quickly generating complete contour dimension data.

5. Coaxiality and Concentricity Detection

Concentric hole systems on prism bases are crucial for positioning accuracy. SIG Vision Measuring Machine automatically evaluates coaxiality and concentricity tolerances. By measuring center coordinate deviations, it automatically calculates the eccentric theoretical distance, effectively assessing the consistency of center positions across multiple holes.

6. Threaded Hole and Counterbore Detection

For prism bases with threaded holes or counterbores, SIG Vision Measuring Machine can perform combined inspection of major diameter, minor diameter, thread depth, and thread hole position tolerance, ensuring reliable screw locking and accurate positioning.

7. Surface Defect and Machining Mark Inspection

Fine scratches, burrs, and machining marks on the prism base surface are clearly visible under a high-magnification optical lens. SIG machines are equipped with programmable multi-angle LED ring light, coaxial light, and contour light. The lighting angle and intensity can be flexibly adjusted according to the base material and surface characteristics, effectively highlighting edge features and surface imperfections for non-contact visual inspection assistance.

III. What Problems Does SIG Vision Measuring Machine Solve?

Based on the above capabilities, the SIG fully automatic Vision Measuring Machine systematically solves three core pain points for prism base manufacturers:

Pain Point 1: Low Efficiency and Large Errors of Manual Measurement

In the past, quality inspectors needed to use calipers, micrometers, height gauges, projectors, and other tools to measure dozens of parameters on each prism base — time-consuming and prone to reading or recording errors. SIG Vision Measuring Machine adopts a one-click fully automatic batch measurement mode. After one programming setup, subsequent inspections are fully automated. The inspection time per part is reduced from minutes to seconds, dramatically improving efficiency.

Pain Point 2: Difficulty in Ensuring Batch Measurement Consistency

Prism bases are typically produced in batches, and consistent inspection data is essential. SIG Vision Measuring Machine uses a high-precision granite base, closed-loop servo control system, and rigorous temperature compensation algorithm to ensure stable and reliable results. Excellent repeatability means hundreds or thousands of measurements yield consistent readings, eliminating human errors and enabling manufacturers to upgrade from sampling inspection to 100% quality control.

Pain Point 3: Lack of Traceability in Inspection Data

Traditional inspection data is often recorded on paper, making it difficult to query or perform process capability (CPK) analysis and quality traceability. SIG Vision Measuring Machine automatically generates illustrated SPC statistical analysis reports for all measurement results. Data can be uploaded in real-time to MES systems, achieving closed-loop quality traceability. This not only helps enterprises "measure more accurately" but also "manage better".

IV. Recommended Product Series & Models

SIG offers various series of Vision Measuring Machines for different sizes and accuracy requirements of prism bases:

• AutoVision Series: Accuracy up to 1.4+L/200μm. Ideal for high-precision batch inspection in 3C electronics, automotive parts, and optical components. CNC programming enables fully automatic cycle measurement.
• SinoVision Series: Accuracy up to 1.2+L/200μm, comparable to high-end German/Japanese imports. Designed for customers with the highest precision requirements.
• MVS Cantilever Fully Automatic Series: Specifically developed for GD&T (Geometric Dimensioning and Tolerancing) measurement. Ideal for prism bases requiring comprehensive evaluation of position tolerance, perpendicularity, flatness, and other geometric tolerances.
• MaxVision Large Travel Series: For large prism bases or optical platform substrates. Moving-bridge structure, measuring range up to 1000mm and above, meeting high-precision inspection of large workpieces.

Users can select the appropriate model and optional configurations (e.g., touch probe, laser probe) based on base size, accuracy grade, and required inspection items.

V. Customer Value Summary

Choosing SIG Vision Measuring Machine for prism base precision dimensional inspection means:

• More accurate data: Micron-level measurement accuracy and high repeatability support process optimization and quality decisions.
• Higher inspection efficiency: One-click fully automatic batch measurement significantly shortens inspection cycles and boosts throughput.
• Stronger quality assurance: Full inspection covers all dimensional and geometric tolerance parameters of prism bases, preventing defective parts from leaking out.
• Smarter quality traceability: Automatic SPC reports with traceable data meet Industry 4.0 quality management requirements.

SIG has been deeply involved in the precision measurement field for many years, providing Vision Measuring Machine solutions to over 3,000 enterprises globally, covering 3C consumer electronics, new energy vehicles, aerospace, optical devices, medical equipment, and more. We continue to use professional precision optical dimension measurement technology to help optical device manufacturers enhance their quality competitiveness and move together toward intelligent manufacturing.

For more product details or to schedule a free sample measurement, please visit the official SIG website: www.sinowon.com