DESIGN AND ANALYSIS OF THE FOUR ELEMENTS OBJECTIVE LENS FOR THE 3.2-4.2µm SPECTRAL REGION

A series of sensors was developed to study the electromagnetic properties of a spark gap with various gaps between hm to 6mm. The gas used for the spark gap was air, at atmospheric pressure, ambient temperature ( 20°C ) and standard air composition. The sensors were developed to study the classical regions of the electromagnetic spectrum commonly called the visible, ultraviolet (W) , and near
infiared (NIR). A review of the üterature was perfomed that concentrated on the subjects of spark formation, optical energy sources (in particular light emitting diodes (LEDS)), optical sensor design, and bolometer design. Based on this review, a number of sensors were designed, built and tested to study the properties of the optical energy sources and the spark gap. The optical properties of the LEDs and the spark gap were studied using a fiber optic cable to couple the light collected by a lens ont0 a sensor that consisted of a photo-diode and transimpedance amplifier. The spectrurn of the light was determined by
a spectrometer. The energies of the LEDs and the spark gap were studied using the light collected by a lem ont0 a bolometer sensor that consisted of an ac excited resistive bridge circuit coupled to a instrumentation amplifier, tuned ac amplifier and a precision full wave rectifier. A method was developed to calibrate the resistive bridge with a series of blue, green, yellow , red and IR diodes. The sensitivity
of the bolometer was found to be 2,971 V/W.