The yearly National Student Solar Spectrograph Competition (NSSSC) is Montana Space Grant Consortium's Education
and Public Outreach (EP/O) Program for NASA's Interface Region Imaging Spectrograph (IRIS) mission. The NSSSC is
designed to give schools with less aerospace activity such as Minority Serving Institutions and Community Colleges an
opportunity for hands on real world research experience. The NSSSC provides students from across the country the
opportunity to work as part of an undergraduate interdisciplinary team to design, build and test a ground based solar
spectrograph. Over the course of nine months, teams come up with their own science goals and then build an instrument
to collect data in support of their goals. Teams then travel to Bozeman, MT to demonstrate their instruments and present
their results in a competitive science fair environment. This paper and poster will discuss the 2011-2012 competition
along with results as well as provide information on the 2012 -2013 competition opportunities.
The conceptual framework for the characterization of systems of gratings and mirrors is reviewed, based on the methods of Lie optics, which represents each optical element by a mapping that transforms a ray in object space into a ray in image space. The mathematical tools of Lie optics are presented, the complete transformation for a single grating is given in terms of its elementary transformations, and imaging equations are derived using this transformation that correspond with well-known expressions for aberration coefficients. Lie algebraic techniques have certain significant advantages over the more commonly used wavefront aberration theory, which will become apparent when the imaging properties of multi-element systems are considered in Part II of this work.
The imaging properties of varied line-space diffraction gratings are presented for cases in which the underlying grating substrate is bent to form a weak cylinder. Bending the flat grating substrate affects its imaging in two ways: it provides focal properties due to the non-zero substrate curvature, and it changes the local groove spacing across the surface of the grating. Aberration coefficients for such a grating are derived, and a numerical example is presented.
We consider the Lie transformation for a general multi- element optical system, and derive expressions for the primary imaging conditions. In order to reduce the computational complexity of the Lie method, which produces successively more complicated expressions after each elementary transformation, we propose a simplified transformation method that makes repeated use of the single- element transformations. The simplified method is applied to a two-element example (the Monk-Gillieson monochromator), and the way is shown for the extension of the method to three or more elements.
The definition of the generalized optical path function for a grating or mirror with a single plane of symmetry is reviewed. The generalized optical path function is then expanded in a series of
wavefront aberration terms using only a few lines of code in the MathematicaTM scientific programming environment. The use of the algebraic capabilities of the MathematicaTM environment
allows straightforward calculation of aberration coefficients that would normally require considerable effort if undertaken by paper and pencil. In addition, the derivation can be carried out to higher order aberration terms, limited only by the capabilities of the computer platform used.
An alternative technique for blazing sinusoidal-profile gratings is discussed. Whereas conventional blazing techniques use an energetic ion beam to mill through a sinusoidal photoresist profile into a substrate, this technque creates the blazed profile in the photoresist itself, without milling into a substrate. Advantages to this technique are discussed, and grating efficiency curves and groove profiles are shown, before and after ion milling. Simulation results that predict the evolution of the groove profile under ion bombardment are also discussed.
We review the focusing properties of a general planesymmetric dispersive system containing a varied line-space (VLS) grating as its dispersive element. A VLS grating is one whose grooves are straight and parallel (when viewed looking down the grating normal) but unequally spaced. Aberration terms for VLS gratings are related to those for holographically produced gratings. The groove pattern is represented by a groove function, which, although less intuitive than the groove spacing, contains information that clearly corresponds to the imaging properties of the grating. The projection of the groove pattern onto the plane tangent to the grating at its center is shown to be useful in describing the focusing properties of the grating; consequently the imaging effects of the curvature of the grating blank itself can be considered separately.