A factor changeable sinusoidal light frequency modulation model of a semiconductor laser for an interferometric displacement sensor

In the paper, a semiconductor laser factor changeable sinusoidal light freq uency modulation model for the interferometric displacement sensor is put f orward mathematically. The shortcomings of the interferometric system based on light frequency ramp modulation, such as Gibb's phenomenon, the spuriou s sideband effect and the relatively small range of the displacement measur ement, are overcome. In particular, by the proper mathematical deductions, the direction of the phase shift according to movement of the measurand (th e tendency towards an increment or decrement) can be shown. Experimental re sults show that our new system is more stable and accurate than the light f requency ramp modulated one.