ISO 23738-2021 pdf download.Fine ceramics (advanced ceramics, advanced technical ceramics)一 Measurement method of spectral refl ectance of fine ceramic thin films under humid conditions.
8 Environmental conditions and control procedures
Expose the test piece to the required environmental conditions before measurmg the spectral reflectance. The test piece should not be removed from the environmental mini-chamber during the series of measurements conducted under a vacuum, a high-humidity environment and a low-humidity environment. The recommended measurement conditions for a vacuum, a high-humidity environment and a low-humidity environment are as follows.
a) Vacuum: evacuate the environmental mini-chamber containing the test piece by connecting one of its valves to a vacuum pump. Evacuate for more than 30 mm.
b) High-humidity environment: place the environmental mini-chamber containing a test piece in the temperature/humidity-controlled chamber. Open both of the valves and expose the test piece to the required temperature and humidity conditions. The temperature and relative humidity of the temperature/humidity-controlled chamber are (23 ± 2) °C and (80 ± 2) %, respectively. The recommended retention time is 20 mm.
c) Low-humidity environment: place the environmental mini-chamber containing a test piece in the temperature/humidity-controlled chamber. Open both of the valves and expose the test piece to the required temperature and humidity conditions. The temperature and relative humidity of the temperature/humidity-controlled chamber are (23 ± 2) °C and (40 ± 2) %, respectively. The recommended retention time is 20 mm.
9 Reflectance measurement procedure
Measure the spectral reflectance within the required wavelength range. For a wavelength range that is shorter than 850 nm, use the following conditions: a wavelength interval of 0,2 nm, a scanning speed below 120 nm/mm, a fast response and a light incident angle of 50 to the test piece. For a wavelength range that is longer than 850 nm, use the following conditions: a wavelength interval of 0,2 nm, a scanning speed below 150 nm/mm, a fast response and a light incident angle of 5° to the test piece.
a) Measurement position: measure the spectral reflectance at the centre of the test piece. An optical diaphragm is not required if the dimensions of the test piece are larger than the window diameter of the environmental mini-chamber.
b) Measurement of reflectance under a vacuum: measure the reflectance under a vacuum after finishing the evacuation procedure.
c) Measurement of reflectance under a high-humidity environment: measure the reflectance under the required humidity conditions after exposing the test piece to the required conditions in a temperature/humidity-controlled chamber. The recommended temperature and relative humidity are (23 ± 2) °C and (80 ± 2) %, respectively.
d) Measurement of reflectance under a low-humidity environment: measure the reflectance under the required humidity conditions after exposing the test piece to the required conditions in a temperature/humidity-controlled chamber. The recommended temperature and relative humidity are (23 ± 2) °C and (40 ± 2) %, respectively.
10 Evaluations of spectral shifts between dry and humid conditions
10.1 General
Evaluate changes in the spectral reflectance of fine ceramic thin films. The evaluation methods used for several typical types of changes observed in the spectra are shown in this clause. The evaluation method should be optimized to obtain appropriate results for evaluating the film optical properties based on the applications.ISO 23738 pdf download.