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在评价地球大气变化中,光学遥感一直在起着越来越重要的作用。这些变化包括大气中存在少量的有毒化合物,利用红外源进行探测便变得格外重要(见《激光集锦》同本期87页的有关文章)。这是因为绝大多数化合物在中红外(8-11μm)波段区中具有旋转振动跃迁“标迹”。探测这些吸收谱线需要线宽很窄的连续可调的源,以致人们能够捕获特征谱线。如果人们采用遥感手段监测大气中化学物质,还要求源具有高的平均功率。由于缺少合适的向长波延伸的非线性材料,这一系统的发展一直受到限制。象硫化银锗(AgGeS_2)、硒化银锗(AgGeSe~2)、
Optical remote sensing has been playing an increasingly important role in assessing the Earth’s atmosphere. These changes include the presence of small quantities of toxic compounds in the atmosphere, and the use of infrared sources for detection becomes of particular importance (see Laser Collection, same article on page 87 of this issue). This is because most compounds have “vibrational” transitions in the mid-infrared (8-11 μm) band region. Detecting these absorption lines requires a continuously adjustable source with a narrow line width so that one can capture the characteristic lines. If people use remote sensing to monitor atmospheric chemicals, they also require sources with high average power. The development of this system has been limited by the lack of suitable non-linear materials that extend to long wavelengths. Like silver silver germanium (AgGeS_2), silver selenide germanium (AgGeSe ~ 2),