# Laboratory Assessment of In-Pavement Airport Lamp's Luminous Intensity Distribution
## 5 Measurement Sensor Calibration  
The analysis of results presented in Table 2 shows that the spectral characteristic [23] of the BH1750 sensor (ROHM Co., Ltd.: Kyoto, Japan) has an influence on the measurement value, and after introducing mathematical correction, it can be similar to the measurement obtained from the professionally certified Sonopan L-200P luxmeter (Sonopan, Louiseville, QC, Canada) [24] (Figure 11). Depending on their function and location, airport lamps differ in their photometric parameters. The use of different colours of emitted light allows the pilot to quickly distinguish them, thus clearly determining the position of the aircraft in airport areas. The most common lamp colours that have been tested in laboratory tests are white, red, green, and yellow. White lamps, depending on the type of lamp and its location, differ in the dimensions of the prisms, so their characteristics are also different. In-pavement airport lamps can also be divided according to the number of light sources, i.e., single- and double-sided lamps, \begin{table}
\begin{tabular}{c c c c c c} \hline
**Airport Lamp** & **Type of Data** & **L-Resolution** & **H-Resolution** & **H-Resolution** & **Sonopan (lx)** \\
**Mode** & **Type of Data** & **Mode (lx)** & **Mode (lx)** & **Mode 2 (lx)** & **Sonopan (lx)** \\ \hline \multirow{3}{*}{2.8A (1\%)} & Mean & 3.38 & 5.00 & 4.60 & 4.42 \\  & Median & 3.33 & 5.00 & 4.58 & 4.42 \\  & Standard deviation & 0.39 & 0.00 & 0.09 & 0.03 \\ \hline \multirow{3}{*}{3.4A (3\%)} & Mean & 60.83 & 61.53 & 61.25 & 59.24 \\  & Median & 60.83 & 61.67 & 61.25 & 59.30 \\  & Standard deviation & 0.00 & 0.32 & 0.00 & 0.26 \\ \hline \multirow{3}{*}{4.1A (10\%)} & Mean & 362.94 & 361.93 & 360.64 & 355.49 \\  & Median & 363.33 & 361.67 & 360.83 & 355.60 \\  & Standard deviation & 0.41 & 0.39 & 0.32 & 1.18 \\ \hline \multirow{3}{*}{5.2A (30\%)} & Mean & 1983.20 & 1993.27 & 2002.87 & 1985.91 \\  & Median & 1983.33 & 1993.33 & 2002.92 & 1988.00 \\ \cline{1-1}  & Standard deviation & 1.46 & 0.78 & 1.07 & 11.54 \\ \hline \multirow{3}{*}{6.6A (100\%)} & Mean & 7948.31 & 7937.18 & 7938.47 & 7946.43 \\ \cline{1-1}  & Median & 7950.00 & 7937.50 & 7938.33 & 7947.00 \\ \cline{1-1}  & Standard deviation & 2.67 & 3.65 & 2.68 & 2.91 \\ \hline \end{tabular}
\end{table} 
Table 2: Results of the BH1750 experiment. which may have the same or different colours, but this does not affect their photometric characteristics. The tested airport in-pavement lamps are single-sided touchdown zone, clear (TDZ), double-sided runway centerline lamps that are clear on both sides (RCL C/C Clear I, RCL C/C Clear II) and clear and red (RCL C/R Clear, RCL C/R Red), double-sided green-yellow taxiway centerline lamp (TAXI G/Y Green, TAXI G/Y Yellow). Measurements were made from 1 m distance at varying levels of airport lamps specified by EASA [1]. In the case of Poznan-Lawica Airport, the threshold values are defined as follows:  
* 1% for power supply current 2.8 A;
* 3% for power supply current 3.3 A;
* 10% for power supply current 4.1 A;
* 30% for power supply current 5.2 A;
* 100% for power supply current 6.6 A. After conducting 50 measurement series, the results obtained for the BH1750 sensor and the certified Sonopan L-200P luxmeter were averaged for all of them. Data are summarised in Table 3.  
Based on the results obtained, functions were determined to approximate the values obtained by the BH1750 sensor in relation to the reference values of the certified Sonopan L-200P luxmeter. Using the Curve Fitter App in Matlab [25], correction polynomials were determined for each type of the tested airport lamp: TDZ (Equation (1)), RCL Clear (Equation (2)), RCL Red (Equation (3)), TAXI Green (Equation (4)), TAXI Yellow (Equation (5)). The variable x  
Figure 11: Spectral characteristic of BH1750 sensor and Sonopan L-200P luxmeter. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} **Airport** \\ **Lamp** \\ **Mode** \\ **(M)** \\ \end{tabular}