Precision Controlled Variable Phase Filter for Imaging Type Two-Dimensional Spectroscopic Tomography

Spectroscopic measurement is being widely used for non-invasive blood sugar measurement in recent past. Imaging type two-dimensional spectroscopic tomography has been designed using wave front division interferometer. Variable phase filter, which has fixed mirror and movable mirror, has been used to introduce the phase shift between rays. Capability of measuring biogenic substances using this method has been proved. Variable phase filter has a piezoelectric actuator which has the stroke of 30μm. However, it is not enough for mid-infrared application. Smooth Impact drive mechanism with longer stroke was used here. However, smooth control is challengeable. This paper proposed the control of SIDM using PID control and Pseudo inverse differentiation. Proposed controller implemented and experiment result proved the effectiveness of proposed method.