【半宽度】(half width)又称“半峰宽”。指分析过程中，所得的信号曲线呈一峰状时，在峰高一半处峰的宽度。此值在分析化学中为一极有用的参数，在不同应用方面有其不同内容。如在气相色谱或高压液本色谱分析中，从所出现的各种流出物的信号峰形曲线上求得此值后，可用来计算色谱峰的面积、计算色谱柱的效能和评价被分离物质之间的分离效能，通常此值越小，仪器的分辨能力越高。又如在光度分析中，评价某一滤光片的透过单色光的性能时，可测其透光曲线，即将各种不同波长的光通过滤光片，分别测期透光率，然后以小组长为横坐标，透光率为纵坐标作图，所得曲线亦为峰形，其半宽度值愈小，由透过的单色光愈窄，其单色性愈好。通常玻璃滤光片其半宽度在60纳米以上，有机染料夹胶滤光片大约为30-40纳米，干涉滤光片一般约为10纳米。 Full width at half maximumfull width at half maximumA full width at half maximum (FWHM) is an expression of the extent of a function, given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value.FWHM is applied to such phenomena as the duration of pulse waveforms and the spectral width of sources used for optical communications and the resolution of spectrometers.The term full duration at half maximum (FDHM) is preferred when the independent variable is time.When the considered function is the normal distribution of the formwhere is the standard deviation and x0 can be any value (the width of the function does not depend on translation). The relationship between FWHM and the standard deviation isAnother important distribution function, related to solitons in optics, is the hyperbolic secant:Any translating element was omitted, since it does not affect the FWHM. For this impulse we have: