Key Challenges and Results in the Design of Cubesat Laser Terminals, Optical Heads and Coarse Pointing Assemblies

This paper presents a state-of-the-art overview of fine beam steering mechanisms for free-space optical communication on satellites. Precise beam pointing is a critical task for the successful operation of free-space optical communication systems. Based on past research and ongoing projects, the use of fast steering mirrors (FSMs) is still the most popular solution for free-space optical communication applications. Although a variety of commercial off-the-shelf (COTS) FSM solutions exist, there is limited publicly available data on these solutions in the space environment. Three main actuation principles are considered (electro-static force actuated, magnetic force actuated, piezo-effect actuated) and reviewed using available data from past space missions. The article describes the most important criteria in the choice of a fine beam steering solution for free-space optical communication in space.

Section: Electromagnetically Driven Mems Fsmmentioning

confidence: 99%

A Review of Mechanical Fine-Pointing Actuators for Free-Space Optical Communication

Milaševičius,

Mačiulis

2023

“…While the AeroCube7 optical head did not include any beam steering capability or gimbal mechanism, relying on a high-performance star tracker for attitude control, and larger beam divergence for link stability, the more recent Click-A incorporated an FPA similar to the OC4 instrument for closed-loop control of the pointing system. Another notable miniaturized system for LEO-to-ground communication is CubeCAT, featuring the optical head developed by TNO [9]. CubeCAT also incorporates an FPA similar to both CLICK-A and OC4.…”

Section: Introductionmentioning

confidence: 99%

“…In a duplex co-located PAT system, as depicted in Figure 1a, a single mirror is used to steer both the transmitted and received optical signal. While this configuration offers the advantage of a simpler design [9,10], it typically requires a separate beacon channel, along with the use of dichroic beamsplitters to separate the send and receive beams. These beam splitters necessitate the use of different data wavelengths on opposing terminals.…”

Section: Introductionmentioning

confidence: 99%

Steering Mirror System with Closed-Loop Feedback for Free-Space Optical Communication Terminals

Graham,

Bramall,

Younus

et al. 2024

Precision beam pointing plays a critical role in free-space optical communications terminals in uplink, downlink and inter-satellite link scenarios. Among the various methods of beam steering, the use of fast steering mirrors (FSM) is widely adopted, with many commercial solutions employing diverse technologies, particularly focusing on small, high-bandwidth mirrors. This paper introduces a method using lightweight, commercial off-the-shelf components to construct a custom closed-loop steering mirror platform, suitable for mirror apertures exceeding 100 mm. The approach involves integrating optical encoders into two off-the-shelf open-loop actuators. These encoders read the signal reflected on purposefully diamond-machined knurled screw knobs, providing maximum contrast between light and dark lines. The resulting steering mirror has the potential to complement or replace FSM in applications requiring a larger stroke, at the expense of motion speed. In the presented setup, the mirror tilt resolution achieved based on the encoder closed-loop signal feedback is 45 μrad, with a mean slew rate of 1.5 mrad/s. Importantly, the steering assembly is self-locking, requiring no power to maintain a steady pointing angle. Using the mirror to actively correct for a constantly moving incoming beam, a 5-fold increase in concentration of the beam spot on the center of the detector was obtained compared to a fixed position mirror, demonstrating the mirrors ability to correct for satellite platform jitter and drift.

“…First, a novel system architecture for future laser crosslinks is proposed. In the last ten years, the key technologies of laser communication systems have been developed and validated by on-orbit missions, adopting large-sized satellite platforms with additional beam-pointing and tracking systems such as gimbal mechanisms [10]. The proposed systems share beam paths for communication and PAT with a single aperture.…”

Section: Introductionmentioning

confidence: 99%

Design of Novel Laser Crosslink Systems Using Nanosatellites in Formation Flying: The VISION

Kim

Park

Seong³

et al. 2022

With growth in data volume from space missions, interest in laser communications has increased, owing to their importance for high-speed data transfer in the commercial and defense fields, spaceborne remote sensing, and surveillance. Here, we propose a novel system for space-to-space laser communication, a very high-speed inter-satellite link system using an infrared optical terminal and nanosatellite (VISION), which is aimed at establishing and validating miniaturized laser crosslink systems and several space technologies using two 6U nanosatellites in formation flying. An optical link budget analysis is conducted to derive the signal-to-noise ratio requirements and allocate the system budget; the optical link margin should be greater than 10 dB to guarantee communication with practical limitations. The payload is a laser transceiver with a deployable space telescope to enhance the gain of the beam transmission and reception. Nanosatellites, including precise formation flying GNC systems, are designed and analyzed. The attitude control system ensures pointing and tracking errors within tens of arcsec, and they are equipped with a propulsion system that can change the inter-satellite distance rapidly and accurately. This novel concept of laser crosslink systems is expected to make a significant contribution to the future design and construction of high-speed space-to-space networks.