What is a ground-based solar spectrograph?
A spectrograph, often used interchangeably with “spectrometer” or “spectroscope,” is an instrument that gathers incoming light and analyzes it by separating out its constituent wavelengths. There are innumerable scientific and technical applications of spectroscopy; most instruments are built for a very specific purpose. Your job will be to decide on a purpose – a scientific goal – and then design and build a spectrograph to meet your own needs. To learn more check out the IRIS tutorial.
What type of science can be done with a spectrograph?
The sun is our closest stellar neighbor, making it an ideal object of study to learn more about the complicated physical processes that take place inside of stars. Each new endeavor in solar science – such as NASA’s IRIS mission – brings a wealth of new information about the sun. But if studying the sun doesn’t sound interesting enough, the possible applications of a spectrograph are limited only to your imagination. Currently scientists are using spectroscopy to answer questions about the Earth’s atmosphere, the health of pine trees, and the location of meth houses - and that’s just in Montana!
Do we have to study the sun?
No! While many teams will gravitate towards solar science, the sun may also be used as a light source for whatever science questions you see fit to answer!
Does our spectrograph have to operate in the visible range of wavelengths?
Due mainly to cost constraints, we expect to see observations made in the visible and near-IR/UV ranges. Efficiency information on the diffraction gratings provided by Richardson Gratings can be found here [grating link].
How will we collect light during the competition?
During the competition, multiple heliostats will be set up for teams to interface with. These are equitorial wedge clock drives modified to hold precision aluminum mirrors. These heliostats will provide a fixed beam of light at an angle of 45 degrees from normal. Click here to download a Google Sketchup file with the competition layout. ink to heliostat documentation (Google Sketchup required).
How do we test and use our instrument without access to a heliostat?
We recommend designing your heliostat with an adjustable base that will allow the optical axis to be tilted up and down. That way, short scans may be performed by simply pointing your device at the sun. If your science goal requires longer continuous scans, you may want to employ an adjustable mirror or other tracking device into your design.
What if the light is too powerful?
An aperture of the maximum allowed size of 4” would collect enough light to generate quite a lot of power at the focal point. Teams must consider the operational limits of their optics and other materials used. Shutters, neutral density filters, and variable gain detectors are all options when controlling for the intensity of incoming light.
Can we use a light source other than the sun?
No; no LASER’s or other artificial light sources may be used in a spectrograph design. Experiments that involve emission spectroscopy, however, are allowed.
Is there a time limit for data collection?
On the day of the competition, each team will have ninety minutes to setup and collect data. Before the competition, we encourage teams to collect as much relevant data as possible.
How do we order our complimentary diffraction grating from Richardson Gratings?
Once your team has decided on a grating, please send your selecton and shipping instructions to Randy Larimer. Thank you to competition judge Chris Palmer and Richardson Gratings for their ongoing support.
Where can we get additional optics?
Besides Richardson Gratings, Newport Corporation, ThorLabs, Edmund’s Optics, and other online retailers supply optical equipment at reasonable costs. Other companies specialize in liquidating surplus optics, and may be an cost effective option for certain items.
What type of lenses/ detector/ other optics/ mounts/ etc. should our team use?
Figure it out! Each optical element has an efficiency that is dependent on wavelength, and will affect your usable signal. Also, think carefully during the design process about the need to align optics as the device is built. Pay close attention to all tech specs to make sure all of your optics will perform as needed. It will be up to your team to review the return policy of any store you order from.
Our team does not have access to a machine shop. Is that a problem?
No! With some creativity and inginuity plywood, PVC, and other low-cost items can be used to form a light-proof and stable optics platform.
Does our spectrometer have to be weather-proof?
The extent of weather-proofing applied is up to individual teams. We recommend that your instrument can withstand at least brief exposure to light showers.
What are the optical specifications of the mirror used in the heliostats?
The heliostat mirrors were chosen for their high quality of surface flatness. This feature ensures that light will be reflected uniformly before entering your spectrometer. The mirrors are aluminum coated, so their efficiency closely matches the reflectance of aluminum curves plotted here[grating link].
Does our team have to be comprised of different majors?
While we encourage a multidisciplinary approach to the competition, there is no requirement to have multiple majors on a team.
Are international teams allowed?
Unfortunately, due to the rules regarding build funds provided by NASA, we are currently unable to accept international teams.
What if it is cloudy or raining during the competition?
In the event that the weather is uncooperative during the competition, artificial light sources (such as vapor lamps) will be provided to test spectrograph performance.
Will there be access to power outlets at the competition?
Yes, standard 120V wall outlets and extension cords will be available.