Senior Optical Systems Architect – Biotech Instrumentation in Paris

We are looking for a Senior Optical Systems Engineer to own the architecture, development, integration, and validation of Rivercell's optical subsystems. You will develop both the patterned-light projection system used to actuate droplets from below the microfluidic chip and the illumination and imaging system used from above to monitor the device and observe cells.

You will treat these optical paths as a coordinated system: projected patterns, chip coordinates, and camera images must remain accurately registered; illumination must be uniform and stable; actuation light must not compromise imaging; and the complete optical assembly must deliver reproducible performance across instruments and over time.

Some of the engineering challenges you will address include:

• Thousands of droplets will be actuated in parallel by spatially patterned light projected through a multilayer chip. The actuation path must provide the required wavelength, irradiance, contrast, projected-pixel size, focus uniformity, and geometric accuracy over a large working area.

• At the same time, the imaging path must observe droplets and cells over a large field of view with sufficient resolution, depth of field, signal-to-noise ratio, and acquisition speed. Both paths must operate through glass, liquids, coatings, and thin-film materials while limiting reflections, stray light, thermal drift, spectral cross-talk, and calibration error.

You will work hand-in-hand with our microfluidic chip, software, computer-vision, electronics, mechanical engineering, bio-laboratory automation, and biology teams. You will define and validate the optical interfaces of the complete instrument while remaining a highly hands-on contributor throughout development. You will be an integral part of an ambitious and exciting startup project from its inception.

• Define the end-to-end optical architecture for the instrument

• Translate product requirements into measurable optical specifications, including wavelength, irradiance, uniformity, contrast, resolution, field of view, depth of field, distortion, etc

• Design and prototype the bottom projection system, including light sources, illumination optics, projection lenses, mechanical alignment, etc

• Design and prototype the top illumination and imaging system, including illumination geometry, cameras, sensors, lenses, apertures, filters, and imaging modes appropriate for droplet monitoring and cell observation

• Develop the geometric and radiometric calibration methods that map projected pixels, physical chip coordinates, and camera pixels to one another and maintain this registration over time

• Model and measure the effect of glass substrates, liquids, coatings, photoconductors, dielectric layers, and chip geometry on optical transmission, aberrations, focus, and contrast

• Lead optical tolerancing and optomechanical co-design, including component placement, datums, alignment procedures, focus adjustment, vibration sensitivity, thermal expansion, serviceability, and manufacturing variation

• Build optical benches and prototypes, define test methods, and perform hands-on characterization of illumination, projection, image quality, modulation transfer, focus, distortion, uniformity, stability, and registration

• Specify synchronization requirements between projected patterns, electrical excitation, illumination pulses, camera exposure, autofocus, and instrument-control software

• Define interfaces with computer-vision and image-processing teams, ensuring that the optical system provides calibrated, stable, and interpretable images without owning the perception algorithms themselves

• Select and manage optical-component and module suppliers, including technical evaluation, custom specifications, prototype qualification, cost and lead-time trade-offs, and supplier-related root-cause analysis

• Develop optical verification plans, acceptance criteria, calibration procedures, and production tests for prototype and small-scale instrument manufacturing

• Lead root-cause analyses for optical and cross-functional failures such as insufficient droplet actuation, non-uniform illumination, blurred or distorted images, unstable focus, registration drift, low contrast, reflections, or camera saturation

• Document optical architecture decisions, models, interface specifications, drawings, calibration methods, design rules, and validated system baselines

• Opportunity to work on a cutting-edge project in the field of biotech

• Opportunity to join an ambitious team and impactful startup among the first employees

• Competitive salary and equity package

• Exciting opportunities for personal and professional growth within the team

You have an engineering degree, MSc, PhD, or equivalent advanced training in optical engineering, photonics, applied physics, imaging science, or a related field.You have 6+ years of relevant experience developing and integrating optical systems for scientific instruments, machine vision, microscopy, medical devices, semiconductor equipment, industrial inspection, projection systems, or related applications.You have taken at least one optical system from requirements and bench prototypes through integration, verification, and a reproducible instrument or product.You combine strong optical-system judgment with a willingness to align components, build test setups, write analysis scripts, inspect images, and solve practical problems in the laboratory.You are comfortable owning both projection systems and imaging systems, even if your deepest expertise is in one of the two.You can reason across optics, optomechanics, electronics, software, materials, thermal behavior, calibration, and manufacturing tolerances.You are autonomous, committed, enthusiastic, and comfortable working with a can-do, creative, and challenging mindset.You are rigorous in experiment design, metrology, documentation, data interpretation, requirements management, and communication of uncertainty.You have excellent communication skills and are fluent in English; professional proficiency in French is helpful but not required.You have previous experience or knowledge in one or more of the following areas:Optical-system architecture, radiometry, geometrical optics, physical optics, imaging performance, and aberration managementIllumination design, projection optics, structured light, DLP or DMD systems, LCoS, LED or laser sources, and optical filteringMachine-vision or microscopy systems, including camera and sensor selection, lens selection, numerical aperture, depth of field, resolution, and signal-to-noise trade-offsOptical-design and simulation tools such as Zemax OpticStudio, CODE V, LightTools, FRED, TracePro, or equivalentOptomechanical design, tolerance analysis, alignment strategies, thermal drift, vibration, and design for assemblyOptical metrology and calibration, including MTF, distortion, irradiance mapping, flat-fielding, focus mapping, spectral measurements, and coordinate registrationHigh-throughput imaging, pulsed illumination, camera triggering, autofocus, and synchronization with physical processesPython, MATLAB, LabVIEW, or similar tools for optical modeling, laboratory automation, image analysis, and data processingPlease let us know in your application if you specifically have experience with one or several of the following:Patterned-light projection onto microfluidic, photoconductor, display, or lab-on-chip devicesBrightfield, darkfield, fluorescence, phase-contrast, or quantitative-phase microscopyMulti-camera imaging systems or tiled acquisitionRegistration between projection and imaging coordinate systems, structured-light calibration, or closed-loop optical controlImaging through multilayer glass, liquids, thin films, or reflective and partially transparent devicesDroplet microfluidics, digital microfluidics, electrowetting, optoelectrowetting, or optoelectronic tweezersTransitioning optical prototypes into qualified modules or small-scale production, including supplier and production-test development