Methods for detecting chloral hydrate in dichloroacetic acid are described. A laser beam is received by the optical system and directed along an optical path. Other aspects provide steering of the inductive field of the device by using a telecoil array and controlling the amplitude or phase of the signals transmitted by each telecoil in the array to create a composite field. A novel power supply and the use of differential amplifiers in connection with a black signal level as a reference voltage are also described.