This paper presents a summary of the performance of the Landsat Operational Land Imager (OLI) spectral filters. An
overview of OLI is presented along with background on filter performance and manufacture. Performance results versus
requirements are presented for all key performance metrics.
The QuickBird telescope is a large-aperture, high-resolution instrument that produces panchromatic and multispectral images of the earth. It has been successfully aligned and is now undergoing final performance verification tests. To help create this unique instrument, Ball Aerospace & Technologies Corp. has invested in the development of a facility to help reduce the time and expense typically associated with the assembly, alignment, and test of complex systems. This facility offers an integrated capability for interferometric alignment and testing of large telescopes, end-to-end image characterization including flight focal plane and electronics, Modulation Transfer Function testing, effective focal length and distortion testing, and radiometric calibration. This paper describes the overall capability of this facility and uses actual data from the alignment and test of the QuickBird telescope to demonstrate the successful completion of that instrument.
The QuickBird telescope represents a significant accomplishment as the first large-aperture, high-resolution, totally unobscured optical system developed as a fixed-price commercial product. The telescope was aligned and tested in a dedicated facility at Ball Aerospace and Technologies Corp. specially developed to reduce the total process time of building and testing complex optical systems. This presentation summarizes design features, mirror- manufacturing results, telescope alignment, and test results.
A problem can arise when a set of optics must be aligned but intrinsic surface errors
dominate alignment wavefront errors. Aligning diamond-turned optics interferometrically at
visible wavelengths is one such example. Diamond-turned optics can exhibit a high-spatialfrequency
surface ripple from the machining process, which, in many cases, can render an
interferogram unintelligible to the point that even serious alignment errors cannot be detected.
In an alignment demonstration conducted last year this problem was encountered head on
and two techniques were applied to extract meaningful wavefront data. The first relied on
spatial filtering of the return wavefront to smooth out the effects of high-slope surface errors.
This approach showed potential in that it is a simple method that can be easily applied. The
second approach used a new software algorithm, available as part of the Zygo Mark lV phase
measuring interferometer, where regions of fringe discontinuities are discarded and the
resultant piece-wise phase map is reconstructed as a continuous wavefront. Using this latter
approach, we were able to precisely align a three-mirror telescope comprised of diamondturned
mirrors and used in a double-pass configuration. The approaches to be described are
applicable to the alignment of infrared and visible sensors and metrology of single surfaces.