# Technology Selection for Inline Topography Measurement with Rover-Borne Laser Spectrometers

## TL;DR

This paper explores adding 3D topography measurement to rover-based laser spectrometers to improve geological analysis on extraterrestrial bodies.

## Contribution

The paper evaluates and compares 3D imaging technologies for integration with rover-borne laser spectrometers.

## Key findings

- Inline microscopic fringe-projection profilometry is a promising 3D imaging technique for rover integration.
- Multiwavelength digital holography offers potential for detailed topography with laser spectrometers.
- Incoherent digital holography is identified as a viable candidate for 3D imaging in space exploration.

## Abstract

This work studies enhancing the capabilities of compact laser spectroscopes integrated into space-exploration rovers by adding 3D topography measurement techniques. Laser spectroscopy enables the in situ analysis of sample composition, aiding in the understanding of the geological history of extraterrestrial bodies. To complement spectroscopic data, the inclusion of 3D imaging is proposed to provide unprecedented contextual information. The morphological information aids material characterization and hence the constraining of rock and mineral histories. Assigning height information to lateral pixels creates topographies, which offer a more complete spatial dataset than contextual 2D imaging. To aid the integration of 3D measurement into future proposals for rover-based laser spectrometers, the relevant scientific, rover, and sample constraints are outlined. The candidate 3D technologies are discussed, and estimates of performance, weight, and power consumptions guide the down-selection process in three application examples. Technology choice is discussed from different perspectives. Inline microscopic fringe-projection profilometry, incoherent digital holography, and multiwavelength digital holography are found to be promising candidates for further development.