Imaging Performance Analysis of an EO/IR Dual Band Airborne Camera

Abstract

An airborne sensor is developed for remote sensing on an aerial vehicle (UV). The sensor is an optical payload for an eletro-optical/infrared (EO/IR) dual band camera that combines visible and IR imaging capabilities in a compact and lightweight package. It adopts a Ritchey-Chrétien telescope for the common front end optics with several relay optics that divide and deliver EO and IR bands to a charge-coupleddevice (CCD) and an IR detector, respectively. The EO/IR camera for dual bands is mounted on a two-axis gimbal that provides stabilized imaging and precision pointing in both the along and cross-track directions. We first investigate the mechanical deformations, displacements and stress of the EO/IR camera through finite element analysis (FEA) for five cases: three gravitational effects and two thermal conditions. For investigating gravitational effects, one gravitational acceleration (1 g) is given along each of the +x, +y and +z directions. The two thermal conditions are the overall temperature change to 30℃ from 20℃ and the temperature gradient across the primary mirror pupil from -5℃ to +5℃. Optical performance, represented by the modulation transfer function (MTF), is then predicted by integrating the FEA results into optics design/analysis software. This analysis shows the IR channel can sustain imaging performance as good as designed, i.e., MTF 38% at 13 line-pairs-per-mm (lpm), with refocus capability. Similarly, the EO channel can keep the designed performance (MTF 73% at 27.3 lpm) except in the case of the overall temperature change, in which the EO channel experiences slight performance degradation (MTF 16% drop) for 20℃ overall temperate change.

Measurement of the Modulation Transfer Function of Infrared Imaging System by Modified Slant Edge Method

“…The imaging quality of an infrared imaging system is generally evaluated by the modulation transfer function (MTF) [1][2][3]. MTF is the magnitude of the optical transfer function (OTF), which is the Fourier Transform of the response of the imaging system to a point source (PSF).…”

Polarization Properties of Quasi-Homogeneous Beams Propagating in Oceanic Turbulence

“…Chen and Li have been researched the coherence properties and polarization modulation of QH beams scattered from anisotropic media [4][5]. The propagation properties of laser beams in random media like turbulence or human tissue are important for applications such as optical imaging, remote sensing and communication systems so more and more researchers are attracted [6][7][8][9][10][11]. The polarization "self-reconstructed" phenomenon in atmosphere turbulence has been known for a long time.…”

Dynamic Modulation Transfer Function Analysis of Images Blurred by Sinusoidal Vibration

“…Sinusoidal vibration is a basic form of mechanical vibration, such as low frequency, rigid body motion due to platform control instabilities and mediumto-high frequency disturbances due to structural elasticity [2]. A convenient form with which to characterize motion degradation quantitatively is dynamic MTF [3,4].…”