AMI: Automatically modulated Irradiator

The continuous decrease in the stratospheric ozone layer is producing an increase in ultraviolet-B radiation (UV-B) reaching the surface of the earth; such an increase in UV-B radiation could produce effects on terrestrial biological processes. In this work a regulator to supply (in the field) additional doses of UV-B radiation, simulating the pattern of the solar ultraviolet radiation, is presented; the regulator set point is not a fixed value at which to maintain the controlled quantity, but rather a numerical coefficient which is used by the system to multiply a variable reference quantity (UV-B solar radiation). As a consequence, the actuator continually modulates the controlled quantity to maintain the ratio between this quantity and the reference quantity unaltered: the pantograph effect. Controlled and reference quantities are monitored by means of UV-B radiometers. Obviously, this principle can be applied to any physical quantity. The Automatically Modulated Irradiator (AMI) is made up of an array of lamps and the respective control which uniformly irradiate a surface with a radiative intensity which follows the intensity of natural UV-B radiation, multiplied by a numerical coefficient which is imposed by the user. In order to uniformly illuminate the surface, the irradiation diagram of lamp, inserted in their housings was specifically realized.