An apparatus for transferring torque magnetically with a primary rotary member and a secondary rotary member. Each of the solar cells has a solar chip having two DC power output terminals and an MPPT unit having two power input terminals electrically connected with the two DC power output terminals, and two power output terminals. The output of the inverter is used to test scanning circuits. Applying a force to one or both ends of the array of beam elements changes the spacing of the grating, and presents a different ruling spacing distribution to incoming radiation, thus altering the diffracted angle among individual diffraction orders of the wavelength.