Cameras for automatic road sign recognition require specific optical characteristics. Inline inspection of each individual part ensures all required specifications are met.

 

 

Abstract

This application note explains the use of the Polispec Lite inline system for measuring the transmittance of windows designed for cameras used in vehicles to automatically recognize road signs. The coatings applied to these windows must provide specific transmittance characteristics at certain wavelengths to ensure optimal performance under all lighting conditions, whether direct or diffuse light. The system automatically measures transmittance during production, discarding any non-compliant windows.

 

 

 

Introduction

In the realm of Advanced Driver Assistance Systems (ADAS), automatic road sign recognition through cameras has become increasingly common. To function correctly in varying lighting conditions—both direct and diffuse light—these cameras are equipped with windows that feature a special coating. This coating must meet stringent optical requirements and is designed to provide a minimum transmittance of 80% at specific wavelengths. Without an effective inline quality control system, inspecting these windows would be time-consuming and complex, with manual measurements prone to errors and delays.

To address this need, the Polispec Lite inline system was implemented to automate the transmittance measurement of each window, ensuring continuous monitoring and allowing only compliant windows to proceed in the production process.

 

Objectives

The objectives of this application are:

• To automatically measure the transmittance of camera windows on the production line, improving quality control efficiency.
• To ensure that coated windows meet the optical specifications they were designed for.
• To automatically discard windows that do not meet the required optical properties.

 

 

 

 

Methodology

The Polispec Lite system is installed directly on the production line, performing transmission measurements with optics specifically sized for the inspection area, avoiding direct contact with the windows. The system analyzes each window, determining its transmittance at specified wavelengths. Windows that do not meet the required transmittance threshold are automatically flagged for rejection.

 

 

 

 

 

Process Steps

1. Coating Application: Windows are coated to meet the specified transmittance requirements.
2. Inline Measurement: The Polispec Lite system continuously measures transmittance at specified wavelengths for each window as it moves along the production line.
3. Quality Control: Windows with transmittance properties outside the optimal range are automatically discarded, ensuring that only compliant products continue in the production process.

 

Results and Discussion

The implementation of the Polispec Lite system enabled the company to:

• Conduct precise, automatic transmittance measurements, reducing the need for manual inspections.
• Enhance quality control by ensuring that only windows with the required optical properties continue in the production process.
• Increase production efficiency by reducing downtime for inspections.

The system enabled real-time decision-making, improving the consistency and reliability of the windows produced for ADAS cameras.

 

Conclusions

The Polispec Lite inline system has proven to be an essential tool for automating the quality control of coatings applied to camera windows used in automatic road sign recognition systems installed in vehicles. Its ability to deliver precise and reliable quality control has contributed to improving production efficiency, meeting the stringent optical requirements, and eliminating the need for error-prone and time-consuming manual measurements.

This automated system not only ensures that the coated windows meet the necessary standards for transmittance but also supports streamlined manufacturing processes, leading to a higher quality product and enhanced performance in ADAS applications.

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