The Hertz/VPM polarimeter: Design and first light observations

TL;DR

This paper introduces the Hertz/VPM polarimeter, a novel submillimeter polarization device using dual VPM technology that operates via translation, offering potential advantages over traditional methods, with successful initial testing demonstrating robustness and efficiency.

Contribution

The paper presents the design, implementation, and initial testing of the first dual-VPM submillimeter polarimeter, highlighting its operational advantages over traditional polarization modulators.

Findings

High efficiency and low instrumental polarization achieved

Identified nonideal behavior linked to wire grid properties

Demonstrated robustness in laboratory and telescope settings

Abstract

We present first results of Hertz/VPM, the first submillimeter polarimeter employing the dual Variable-delay Polarization Modulator (dual-VPM). This device differs from previously used polarization modulators in that it operates in translation rather than mechanical rotation. We discuss the basic theory behind this device, and its potential advantages over the commonly used half wave plate (HWP). The dual-VPM was tested both at the Submillimeter Telescope Observatory (SMTO) and in the lab. In each case we present a detailed description of the setup. We discovered nonideal behavior in the system. This is at least in part due to properties of the VPM wire grids (diameter, spacing) employed in our experiment. Despite this, we found that the dual-VPM system is robust, operating with high efficiency and low instrumental polarization. This device is well suited for air and space-borne applications.