I. Performance Parameters

• Absorptivity: The proportion of incident radiant energy absorbed by a substance.

• Reflectance: The proportion of incident radiant energy reflected by a substance, including specular reflection and diffuse reflection.

• Transmittance: The proportion of incident radiant energy transmitted through a substance.

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For instance, the coating specification shown in the figure below states: at an incident angle of 45°, reflectance shall be no less than 88% at 770 nm; at an incident angle of 45°, transmittance shall be no less than 70% at 550 nm.

II. Working Principle of Spectrophotometers

• To test sample transmittance: Place the sample between the two channels so the light beam passes through the sample.

• To test sample reflectance: Place the sample on the same side of both channels so the light beam is reflected off the sample surface.

1. One beam is reflected to a reference detector, which captures reference light energy to correct energy drift caused by light source fluctuations.

2. The other beam penetrates the sample, reshaped by Collimator 3 and Collimator 4 before entering the measurement detector on the far right.

During actual measurement, two energy readings are acquired (with and without the sample). The transmittance of the sample is calculated by comparing the two energy values.

III. Transmittance Measurement

An integrating sphere is commonly adopted as the receiver to eliminate interference from reflected light reaching the detector. Its working principle is described below:

The structural diagram below shows a testing setup for measuring the transmittance of optical panels:

After mastering the basic principles and testing methods of transmittance measurement, how can measurement data be acquired rapidly and accurately in real production and research? This is exactly the core advantage of our ATM-10 Lens Transmittance Uniformity Tester!

ATM-10 features:

• Supports transmittance testing for various sample types

• Complies with transmittance inspection requirements of multiple standards

• Intuitive and user-friendly software interface

• Calculates full-spectrum transmittance; customizable spectral bands to meet diverse testing demands

• Multi-function testing: transmittance measurement, uniformity inspection, polarized lens testing

• Automatic generation of professional test reports