Finite-difference time-domain analysis of the celestron-8 telescope

Electromagnetic interference analyses of large complex systems demand large computational resources and give limited information on general types of systems. A finite-difference time-domain (FDTD) code was used to determine the response of a "generic" optical system to micron ave radiation. A plane wave with a Gaussian pulse excitation was used along with "point sensors" within the system model to determine time and frequency response. In the low-frequency region, ramped sinusoidal excitation from a point within the sensor was used to determine angles of high sensitivity and field distributions within the sensor. From these field distributions, resonance modes were identified that are similar to those found in a simple cylindrical cavity.