train_dataset_RAW

## 1 FILE CONTENTS ############################################# <br> 2101 x 40010 values: <br> - 1 header row, which corresponds to the 40002 resolved wavelengths and 8 element names (C, Si, Mn, Cr, Mo, Ni, Cu, Fe). <br> - 2100 spectra (rows): 50 spectra of 42 distinct targets. <br> Note that the dataset occupies significantly less RAM when loaded than the file's disk sizes (cca. 50 %). <br> Note that the column names may be modified by the software/library used for processing the spectra. Hence, we advise increased caution when extracting the wavelengths. <br> Alternatively, you can use the wavelength values provided separately in the wavelengths.csv file. <br> ## 2 DATA ACQUISITION ############################################# <br> The dataset was collected from metallic targets. Each target's surface was homogenized using a 800 grid sandpaper and cleaned with isopropyl alcohol using paper towels. <br> The targets were sampled at distinct spots in single-shot mode, collecting a single spectrum from each individual spot. There are a total of 50 spectra available for each target. <br> A 1064 nm Nd:YAG laser was used for ablation with a pulse energy of 95 mJ, 10 ns pulse width. The laser pulse was focused into a spot with a diameter of 0.2 mm. <br> The collected emission was resolved with an echelle spectrograph in the 240--1000 nm spectral range (40002 resolved wavelength values), resolving power {\lambda} / {\Delta\lambda} = 6000. <br> The resolved emission was recorded using an EMCCD camera with a 1.5 us delay and 50 us gate width (exposition time). <br> The spectra were not intensity calibrated! This, in combination with the long gate width is part of the challenge.

## 1 文件内容 #############################################
本数据集包含2101行 × 40010列的数据：
- 1行表头，对应40002个已解析的波长以及8种元素名称（C、Si、Mn、Cr、Mo、Ni、Cu、Fe）。
- 2100条光谱（每行代表一条光谱）：对应42个不同测试样品，每个样品配有50条光谱。
请注意，该数据集加载后占用的随机存取存储器（RAM）远小于其磁盘存储容量，仅约为磁盘大小的50%。
此外，光谱处理所用的软件或库可能会修改列名，因此在提取波长时请格外谨慎。
您也可以使用单独存储于wavelengths.csv文件中的波长数值。

## 2 数据采集 #############################################
本数据集采集自金属测试样品。每个样品的表面均使用800目砂纸进行均质化处理，并使用浸有异丙醇的纸巾擦拭清洁。
测试样品在不同点位以单次采集模式进行采样，每个点位采集一条光谱。每个测试样品共对应50条可用光谱。
实验采用1064 nm的掺钕钇铝石榴石（Nd:YAG）激光器进行烧蚀，脉冲能量为95 mJ，脉冲宽度为10 ns。激光光斑经聚焦后的直径为0.2 mm。
采集到的发射光谱通过阶梯光栅光谱仪（echelle spectrograph）在240–1000 nm的光谱范围内进行解析，共得到40002个已解析的波长值，光谱分辨率为λ/Δλ = 6000。
解析后的发射光谱通过电子倍增电荷耦合器件（EMCCD）相机进行记录，采集延迟为1.5 μs，门宽（即曝光时长）为50 μs。
所有光谱均未进行强度校准，这一因素结合较长的门宽，共同构成了本数据集的一项挑战。