In December 2022, NASA launched the Lunar Flashlight Satellite to find surface water ice in the moon’s craters. The satellite uses photonic mechanisms to aid its search, specifically four lasers using near-infrared beams. The Lunar Flashlight is just one of many spacecrafts that use photonic components to carry out missions. In this article, we’ll explore the use of photonics in space via small components like optical sensors, encoder discs, and lasers.

Photonics In Space: Mission Critical Aspects Of Optical Sensors

Optical sensors are frequently used in space missions because they aid navigation, imaging, and spectroscopy. In addition, reticles are a critical component of optical sensors as they offer a reference point for crucial measurements. Let’s delve into how different space missions employed these sensors.


The Hubble Space Telescope uses optical sensors to point the telescope in the right direction. Optical sensors like star trackers and fine guidance sensors achieve this by analyzing guide stars and providing information that would adjust the telescope’s pointing and trajectory. Reticles inside the telescope aid point precision and correct distorted images.

Optical sensors were similarly employed in the New Horizons mission to observe Pluto. The craft’s optical navigation camera took pictures of stars to help the flyby spacecraft navigate its trajectory toward the dwarf planet.

Imaging & Spectroscopy 

The Lunar Reconnaissance Orbiter used optical sensors like cameras and spectrometers to generate high-resolution maps of the moon’s surface. Reticles within the sensors measured the scale and distance of lunar surface features. The orbiter’s spectrometers measured thermal emissions to provide data about the surface temperature. In contrast, the camera provides reflective properties of the lunar surface that were used to understand our moon’s chemical and physical composition.

Optical sensors and spectrometers both use light to perform their mission-critical tasks. For example, optical sensors use light to detect objects and sense proximity to celestial objects, enabling safe navigation. Meanwhile, spectrometers use their target’s spectral signature to gather data about its chemical makeup.

Photonics In Space: Optical, Magnetic, And Electric Encoders

Optical, magnetic, and capacitive encoder discs are used in spacecraft missions primarily to measure position and motion. The type of encoder chosen depends on their working environment, precision requirements, and mission objectives. Since their operative uses don’t vary widely, we’ll explore the inputs they require for measurement and the different missions in which they’ve played a role.

Optical Encoder Discs

Optical encoders are the most common encoder discs in spacecrafts and optical sensors. The circular discs within the encoder are etched with “gratings,” which are lines with varying degrees of transparency. At Photo Solutions, we specialize in encoder disc fabrication with 5mm to 600mm diameters. In addition, we offer glass encoder discs, transmissive mode, and reflective mode glass discs.

Optical encoders are often used in aerospace applications. For example, optical encoders were used on Mars rovers to measure the speed and position of the rover’s wheels. As light passes through the gratings, an optical sensor analyzes the pattern to determine the wheel’s position and speed.

Magnetic Encoder Discs

These types of encoders require the input of magnetic fields to determine the position of moving parts like wheels or rotors relative to a stationary platform called the stator. Magnetic poles are placed in the moving parts of the encoder, while the stator is equipped with sensors that interact with the magnetic field. The sensors recognize changes within the magnetic field and use the data to measure position, distance, and motion. For this reason, magnetic encoders were also used in two Mars rovers to calculate the position and the distance traveled while in motion.

Photo Solutions fabricates magnetic encoder discs in the form of mylar encoder discs, reflective mylar encoder discs, and reflective aluminum encoder discs. Additionally, we can provide protective liners and adhesives and bond to other materials.

Capacitive Encoder Discs

This encoder requires capacitance input to measure motion and position. Capacitance is the amount of electrical energy stored in the two capacitor plates. Changes within the electrical field allow the plate distance to be measured. Capacitive encoders were used to detect the position of the Parker Solar Probe’s Sunshield, which protected it from radiation and heat.

Photonics In Space: Lasers And Spectroscopic Capabilities

Lasers are a vital photonic tool in space exploration because they can execute diverse tasks and provide critical information. We’ll focus on how the Lunar Flashlight Satellite used a reflectometer outfitted with remote-sensing lasers to conduct spectroscopic functions. Specifically, mapping and identifying ice in the dark regions of vast moon craters.

In order to find water, the Flashlight’s lasers emit near-infrared beams into the craters. When the beam hits dust and rock, it’s reflected to the spaceship. Surface ice, on the other hand, absorbs the beam, establishing the target’s location. The satellite’s detectors measure the amount of light reflected and use the data to map crater territory. They can also isolate certain wavelengths that reveal the amount and distribution of water found. In addition, NASA has used lasers for remote sensing on the Lunar Reconnaissance Orbiter and the Mars Global Surveyor. 

Many optical components like laser diodes, optical fibers, beam splitters, beam expanders, and more play a role in laser functionality. Components like these provide control over the laser’s activation and transmission distances, as well as improve beam divergence and expansion. As advancements are made to optical components, the capabilities of lasers will grow by penetrating deeper, detecting more, and identifying a greater range of biosignatures, which makes them an incredible asset in learning more about space.

Photo Solutions’ Small Components That Enable Photonics In Space

Space exploration requires photonic components that are incredibly sensitive and exacting. Photo Solutions applies rigorous standards to our processes and equipment to fulfill this need and works with aerospace clients to customize mission-critical components. Since we’ve already covered our encoder discs and reticles, let us explore the other Photo Solution products used in space.

Encoder Scales

Photo Solutions has thirty-three years of experience making custom encoder scales with lengths from 2mm to 800mm. We can also implement transmissive and reflective materials to add diverse capabilities for aerospace applications. Our fabrication materials include lightweight, durable options ideal for space travel, like aluminum, glass, quartz, or film. Additionally, applications of low to high-reflective chrome and gold coating are available.

Calibration Targets

To produce calibration targets for space, we customize the surface’s shape grid pattern to produce calibration targets for space and apply photolithography to create distinct edge features for accurate calibration down to a 2um resolution. This level of precision enables calibration targets to convey data on equipment performance and images accurately.

Trust Photo Solutions With Your Photonic Component Needs

Space holds the promise of the unknown, and learning how tiny photonic components are beginning to unravel its mysteries is exciting. At Photo Solutions, we play our part in providing answers by producing and customizing encoder discs, scales, reticles, and hub and disc assemblies. Please explore our website to find components for your next aerospace project.