Senior Opto-mechanical Engineer

Commonwealth Fusion Systems•Devens, MA

1d•$134,000 - $205,000•Hybrid

About The Position

Commonwealth Fusion Systems is assembling the SPARC tokamak, which aims to be the first magnetic fusion device to produce more fusion power than it consumes. The Photonics Engineering department is seeking a Senior Opto-mechanical Engineer to join the Long Wavelength Diagnostics team and help deliver diagnostic capabilities including Laser Interferometry, Thomson Scattering, UV/VIS/IR Imaging and Spectroscopy, Electron Cyclotron Emission Radiometry, and Edge Scanning Reflectometry. As SPARC moves from design into assembly and commissioning, this engineer will work with diagnosticians, scientists, engineers, CAD designers, and technicians to complete designs and deliver systems from the tokamak, through the Tokamak Hall, and into the Diagnostic Labs. The role focuses on packaging optical and waveguide assemblies and designing active and passive alignment systems that maintain long beam paths through thermal cycles, machine motion, and operating conditions including high magnetic fields, vacuum, and radiation. The senior engineer will lead opto-mechanical work on medium- and long-term problems, mentor other engineers, and help develop CFS’s opto-mechanical capabilities for future projects. The role includes carrying designs through final design review, release, procurement, and build; preparing models, drawings, specifications, and design review packages; and providing hands-on support for assembly, installation, alignment, calibration, and commissioning. The position also contributes to safety practices for laser, microwave, vacuum, and high magnetic field work. The full-time position offers a salary range of $134,000–$205,000, plus equity and benefits. Salary depends on level, location, qualifications, and experience.

Requirements

Bachelor’s degree or higher in mechanical engineering, optical engineering, engineering physics, or a related field.
At least 8 years of opto-mechanical or precision mechanical design experience, or at least 6 years with an advanced degree.
Experience leading opto-mechanical design of precision optical instruments or systems from concept through build, test, and deployment.
Experience designing optical mounts and packaging, including kinematic and semi-kinematic mounts, flexures, optic bonding, and athermal design.
Experience designing and implementing alignment mechanisms and procedures for multi-element optical systems.
Experience performing tolerance analysis and error budgets, and using structural and thermal FEA to predict optical performance.
Proficiency with 3D CAD and producing drawings to GD&T (ASME Y14.5).
Hands-on laboratory experience assembling and aligning optical systems.
Strong communication skills to gather inputs and share information across partner teams.
First-principles approach and ability to understand tradeoffs that bridge engineering and physics.
Bias toward action and engineering judgment to produce robust, simple designs quickly.
Attention to detail and ability to pivot between topics multiple times per day.
Ability to occasionally lift up to 50 lbs.
Ability to perform activities such as stooping, climbing, typing, standing, or sitting for extended periods.
Dedication to safety in the presence of industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead, high voltage, and cryogenics.
Willingness to occasionally travel or work required nights, weekends, or on-call.
Compliance with U.S. laws concerning export-controlled or protected technologies or information is required; any offer is contingent on the need for compliance.

Nice To Haves

Master’s degree or PhD in mechanical engineering, optical engineering, engineering physics, or a related field.
Familiarity with optical design and CAD software such as Zemax OpticStudio and Siemens NX, including Teamcenter.
Experience packaging microwave or millimeter-wave waveguide or quasi-optical assemblies, such as corrugated waveguide, miter bends, horn antennas, and polarizers.
Contributions to plasma diagnostics or large physics facilities such as tokamaks, laser facilities, accelerators, or telescopes.
Experience designing for harsh environments, including ultra-high vacuum, high magnetic fields, radiation, cryogenic conditions, or high vibration.
Experience with active alignment and beam stabilization, including motorized mounts, PSDs or quad cells, camera-based feedback, and Python or MATLAB for analysis and automation.
Experience designing optically transparent vacuum boundaries (windows) and optics for harsh environments.
Experience with beam delivery for high-power or pulsed lasers and familiarity with laser safety (ANSI Z136).
Experience managing suppliers and external engineering resources.
Ability to clearly express and critique ideas and mentor others.
Emphasis on elegance and simplicity over complexity.

Responsibilities

Lead opto-mechanical design and close-out of SPARC long-wavelength diagnostic subsystems, carrying designs through final design review, release, procurement, and build.
Design mounts, enclosures, and packaging for optical and waveguide assemblies along beamlines from the tokamak through the Tokamak Hall to the Diagnostic Labs.
Design and implement active and passive alignment systems to establish and maintain alignment over long paths and through thermal and mechanical disturbances.
Develop tolerance and alignment error budgets and perform or direct structural, thermal, and vibration analyses, feeding results into optical and microwave designs.
Collaborate with diagnosticians, scientists, and optical and microwave engineers to translate measurement requirements into cost-effective, manufacturable designs, and manage interfaces with tokamak, building, and mechanical integration teams.
Work with CAD designers to produce models and GD&T drawings, prepare specifications and design review packages, and work with vendors and machine shops on build, inspection, cost, and lead-time tradeoffs.
Plan and provide hands-on support for assembly, installation, alignment, calibration, and commissioning in the Tokamak Hall and Diagnostic Labs; resolve technical issues encountered during manufacturing and installation.
Provide technical leadership and mentorship; review the work of engineers, designers, and contractors; and contribute to opto-mechanical standards, workflows, and best practices.
Contribute to a strong safety culture, including laser, microwave, vacuum, and high magnetic field safety practices, while helping commission and operate SPARC diagnostics.