A light transmittance meter-also known as a transmissometer or transmission tester-is a device used to measure the visible light transmittance of transparent or semi-transparent materials. It primarily encompasses three types: visible light, ultraviolet, and haze transmittance meters. This instrument is widely utilized for assessing the optical properties of products across various sectors, including automotive manufacturing, aerospace, glass products, sunglasses, and sun-protection films. Notably, the testing of automotive windshield transmittance must adhere to the safety standards stipulated in the *Technical Conditions for Road Vehicle Operation Safety*, requiring a minimum transmittance of ≥70%.
The instrument employs an LED light source, features a measurement range of 0–100%, and offers an accuracy of ≤±2%. It supports dual-mode testing: measuring both haze (defined as the ratio of scattered light flux to transmitted light flux) and light transmittance (defined as the ratio of transmitted light flux to incident light flux). Mainstream models-such as the DRTG-81-feature a split-unit design, a copper probe, and power supply via two AA batteries. These units are capable of measuring materials up to 15 mm in thickness, operate within a temperature range of 0°C to 40°C, and include functions for data storage, automatic calibration, and a backlit LCD screen. Certain advanced models integrate a three-channel light source system for simultaneous testing; these support CIE-A/C/D65 standard illuminants and comply with international testing standards such as GB/T 2410 and ASTM D1003.
