ASTM E808-23

Overview

ASTM E808-23: Standard Practice for Describing Retroreflection is an international standard developed by ASTM to provide a common framework for describing, specifying, and measuring retroreflection. Retroreflection is defined as the reflection process in which reflected light is preferentially returned in directions close to the opposite of the incident rays, a property crucial in applications like road safety signs, vehicle license plates, clothing, and pavement markings.

This standard delineates uniform terminology, alternative geometrical coordinate systems, and precise procedures for designating angles associated with retroreflectors and measuring their performance. By standardizing retroreflection measurements, ASTM E808-23 helps ensure consistency, accuracy, and comparability of data throughout different industries and across borders.

Key Topics

ASTM E808-23 addresses several core concepts and definitions related to retroreflection:

• Terminology Standardization: Provides clear, harmonized definitions for terms such as coefficient of retroreflection, coefficient of luminous intensity, entrance angle, observation angle, and presentation angle, many of which reference or refine definitions from the CIE (International Commission on Illumination).
• Geometric Coordinate Systems: Introduces and explains multiple coordinate systems-including the CIE (goniometer) system, the Intrinsic system, the Application system, and the Road Marking (RM) system-to enable precise description and measurement of retroreflection under varied conditions.
• Specimen and Illumination Geometry: Describes methods for specifying the geometry of retroreflectors relative to the intended application and for detailing the geometry of both the illumination and observation setups.
• Measurement Practice: Details procedures for designating key angles (entrance, viewing, observation, orientation, rotation, etc.) and sets forth conventions for describing aperture sizes and angular measurements, helping achieve reproducible retroreflection measurements.

Applications

The consistent framework provided by ASTM E808-23 benefits a wide range of practical applications, including:

• Traffic Safety: Standardizing the measurement and specification of retroreflective surfaces for road signs, highway markings, and vehicle license plates to enhance night-time visibility and road safety.
• Material Manufacturing: Assisting manufacturers of retroreflective materials-such as beaded paints, reflective sheeting, and prismatic devices-in quality assurance, product comparisons, and compliance with international requirements.
• Laboratory Testing: Enabling laboratories worldwide to utilize harmonized testing procedures for retroreflection, improving the reliability and comparability of test data regardless of location.
• Research and Development: Supporting advancements in retroreflective technologies by providing a foundational reference for the geometric and photometric characterization of retroreflectors.

Related Standards

Several other standards and documents are referenced within ASTM E808-23 or are commonly used in conjunction with it:

• ASTM E284: Terminology of Appearance, providing terminology fundamentals relevant to retroreflection.
• Federal Standard No. 370: Instrumental Photometric Measurements of Retroreflecting Materials and Devices.
• CIE Publication 54.2: Retroreflection - Definition and Measurement, outlining the CIE approach adopted and further defined in ASTM E808-23.

Practical Value

Implementing ASTM E808-23 ensures uniformity in the description, specification, and measurement of retroreflective materials and devices. Whether in regulatory, manufacturing, or research settings, this standard enhances the clarity and precision of communication around retroreflection properties-ultimately supporting higher product quality, improved safety, and easier market access on a global scale.

Keywords: retroreflection, ASTM E808-23, retroreflector, measurement, CIE goniometer system, observation angle, entrance angle, luminous intensity, road marking, reflective material, international standard