Low-budget Spectrographs designed for specific instructional lab applications.

Sometimes in beyond the first year laboratory applications, it becomes useful to record a spectrum. We will present a spectrograph that is composed of a reflection diffraction grating, a lens, a camera/webcam, and 3D printed parts that can cost as little as ~ $200 (most commercial spectrometers cost closer to $2000). Despite the low budget and parts, we have already been able to measure the separation between the sodium D-lines (separated by ~ 6.0 angstroms) and the isotope shift between the hydrogen Balmer alpha line and equivalent deuterium line (~1.7 angstroms). We believe that the theory behind this spectrograph is simple enough for undergraduate students to understand, and that students would benefit from building and then using such a spectrograph in many applications.