| 摘要 |
PURPOSE: To compensates a pyramid wobble between facets by allowing a correction value of a look-up table to correspond to one of facets of a polygon and detecting which facet of the polygon is active at present to incorporate the concept of an axial beam in an image forming device using an overall spherical optical system. CONSTITUTION: A look-up table 236 has the same number of items as facets of a polygon 214 and determines fixed errors of facets 216 of the polygon 214. Consequently, when a polygon facet detector 234 generates a signal, which indicates which facet is active at present, and outputs the signal to the look-up table 236, the look-up table 236 outputs a correction factor. A controller converts the error signal from the look-up table 236 to a driving signal of a variable wavelength light source 208 or a variable refractive index prism 232. |
