  Fourier transform power spectra of major axis cuts in V and Halpha images
were made for a sample of 9 irregular galaxies. These power spectra reveal
structure over a wide range of scales. For 6 of the galaxies the power spectrum
slopes at intermediate scales (1-400 pc) in the V-band images range from -1.3
to -1.5. The similarity of slopes suggests that the same processes are
structuring these systems. These slopes are slightly shallower than what is
observed in other galaxies in HI, molecular emission, dust extinction, and
optical light. Three of the galaxies have flat power spectra like noise from
the sky; these three galaxies are relatively indistinct in the direct images.
The power spectrum slope for Halpha steepens with increasing star formation
rate, ranging from a shallow value comparable to the noise at low rates to a
steep value with a slope of -1.5 at high rates. This change reflects the
increasing areal filling factor of Halpha emission with increasing star
formation rate, and an apparently universal slope inside the Halpha regions
that is comparable to that for Kolmogorov turbulence. The power spectrum of HI
in one galaxy has a steeper power law, with a slope of -2.9. The fact that the
power laws of star formation are about the same for dwarf galaxies and giant
spiral galaxies suggests the microscopic processes are the same, independent of
spiral density waves and galaxy size.
