The Multi-Axis Raman Imaging and Analysis (MARIANA) project aims at building an affordable, multi-functional and expandable motorized scanning stage for microscopes and spectrometers. The project is a result of necessity. As a high-pressure research group, we often find ourselves measuring tiny (less than a few hundred micron) samples under the microscope. The manually operated stage that comes with our Raman system, while convenient to use, leaves much to be desired on the accuracy side. Commercial motorized stages may fit the bill, but with caveats: First, they are quite pricey – a decent one can cost over $10k. Second and more importantly, we measure our samples in all kinds of compartments (“cells”) – from a DAC the size of a baseball and weight a few hundred grams, to cryostats with meter-long arms weighing at a few kilograms. A commercial stage that fits this large range of form factors and loads is hard to find. So, we decided to build our own.
Our design is largely based on Openstage (many thanks to Dr. Robert Campbell!), which uses stepper motors and an Arduino microcontroller to achieve sub-micron motion accuracy. The major difference is that, since our microscope has a fixed head, focusing is achieved by moving the stage, instead of the objective. In other words, our design serves as an add-on upgrade to existing microscopes, instead of a build from the scratch.
The MARIANA project is at its early stage. TAMS students Anvita, Aishani and graduate student Bibek built the hardware, and high-school intern Steven wrote the first version of GUI. We are writing the codes for sophisticated motion control, stage-spectrometer synchronization, and a fully functional GUI including post-scan analysis and data visualization. Accomplishing these goals are by no means the end of the project though. New capabilities will be added driven by research need. We borrow the “axis” concept from the beamline control software at the Advanced Light Source: An axis is any physical quantity that can be scanned from value 1 to value 2 – these include stage positions, pressure, temperature, wavelength etc. New axes, both hardware and code, will be designed as plug-in modules to the existing stage, thereby giving us great flexibility in experiments. For example, the next project we have chalked out is to use stepper motors and servos to control the pressure of our hydrostatic pressure cell. Combined with the scanning stage, this will allow us to map the phase segregation of biomolecules in deep-sea environments.
MARIANA is an open platform. CAD files, codes and build instructions will be uploaded to our Github repository. We built our 3-axis stage at ~$2k; by substituting commercial parts with custom-machined ones, we expect the cost can be cut down to ~$1k. We are happy to discuss our build experience with those interested in implementing the design. We also welcome students, particularly those at high-school and undergraduate levels with a passion in hands-on instrumentation, to join the project. You will get the chance to learn CAD, machining skills, as well as coding in C, Python and LabVIEW. Speaking from the PI’s personal experience, nothing beats making your own tool and putting it to work.
– Hao