FFT后得到的剖面线功率谱代表什么意义？？

哪个软件，详细一点吧

picoscan5

MI用户手册中没有PSD
下面是VEECO用户手册中的:
13.1.1 FFTs, PSDs, Autocovariance and RMS
Two off-line NanoScope commands, Power Spectral Density (Analyze/PSD) and 2D Spectrum
(Modify/2D Spectrum), use Fourier analysis to extract information from images. A third method,
Autocovariance (Analyze/Autocovariance), uses a related, discrete method for analyzing images.
Applications of all three features are discussed briefly in this section to assist the reader. Features
are discussed further in their own sections.
Relating FFTs, PSDs, Autocovariance and Root Mean Square (RMS)
Fast Fourier transforms (FFTs), power spectral densities (PSDs), autocovariance and Root Mean
Square (RMS) roughness are interrelated mathematically. Their relationship may be stated as
follows: PSD=FFT^2=FFT{ACF}=RMS^2
The (one-dimensional) power spectral density (PSD) of a surface is equal to the square of its
Fourier transform (FFT) and is also equal to the Fourier transform of its autocovariance function
(ACF), or the RMS value squared. Both one- and two-dimensional PSDs are calculated
automatically and displayed by the Analyze/ Power Spectral Den