Straylight

Does your project have a straylight issue?
Maybe there is one you don't know about yet?

We can help you to identify and quantify straylight requirements of your optical system early in the design process or analyse existing designs to eliminate unwanted light scattering or ghosting.

Drawing on 16 years of experience in straylight analysis and simulation we helped customers in the space industry to improve satellite optics or in the manufacturing industry to enhance the accuracy of laser scanners as well as communication systems providers to increase the sensitivity of laser communication terminals, to name but a few.

Simulation of the nominal beam in a spectrometer.
Nominal beam in a spectrometer for earth observation from space simulated with FRED. The colours correspond with different wavelength.
*doi: 10.1117/12.2296239
Simulation of ghosts in the spectrometer caused by higher order diffraction.
Simulation of ghosts in the earth observation spectrometer caused by higher order diffraction. Only ghosts above a particular power threshold are shown. The colours correspond with different wavelength.
*doi: 10.1117/12.2296239

If possible, straylight should be considered in the early design phase of an optical system to avoid project delays and an increase of development costs. Unfortunately the impact of unwanted light paths on system performance is frequently underestimated or even just considered in hindsight.

Whether taken into account right from the beginning or applied in time of need, we can provide a matching straylight correction strategy.

Our services comprise:

  • straylight design, analysis and simulation of optical systems from early concept phases up to detailed design and realisation
  • definition of straylight verification, characterisation and correction strategies
  • selection of surface coatings or treatments to minimise straylight
  • specification and break down of straylight requirements for optical systems, subsystems and equipment
  • straylight measurement and definition of measurement parameters
  • interpretation of measurement and BSDF generation for various tools
Straylight originating from a grating inside a BSDF measurement facility.
Straylight measurement of a convex grating with production artefacts inside a BSDF measurement facility. The third beam from the left is the laser light source targeting the grating, second from left is the first order peak. The concentric rings originate from artefacts caused by the production process of the grating.
**doi: 10.1117/12.2536219
Measured BSDF of first order peak.
Measured BSDF (bidirectional scatter distribution function) of first order peak.
***doi: 10.1117/12.2312099
Simulated BSDF of first order peak.
Simulated far field diffraction of a synthetic grating profile with superimposed additional gratings. The additional gratings were superimposed to mimic the production artefacts.
***doi: 10.1117/12.2312099

Beside our expertise on straylight minimising designs we utilise the following best of breed software products for the simulation and detailed analysis:

  • FRED, Photon Engineering
  • ASAP, Breault Research
  • Zemax OpticStudio, Ansys
  • SolidWorks, Dassault Systèmes

Of course, working with a variety of software products targeted for specific simulation tasks does require the management of different data formats. We have developed not only the data manipulation tools to enable an efficient simulation workflow including the input data from your project but also tools to visualise the results with respect to design parameter sensitivity and manufacturing tolerances. Our software engineering also develops the post processing routines to transform the simulated data into meaningful results for your project.

Optical simulation of a lens system.
Optical simulation of a plastic lens system with FRED for thermal analysis. The image shows the irradiance distribution on critical surfaces.
****doi: 10.1117/12.2296071
Hotspot analysis of the baffle.
Hotspot analysis using a grid mesh of the baffle. The dviz software package allows the quantitative analysis of particular cell values.
****doi: 10.1117/12.2296071

*doi: 10.1117/12.2296239 Instrument pre-development for flex mission, International Conference on Space Optics - ICSO 2016
**doi: 10.1117/12.2536219 Straylight of curved gratings: an interlaboratory comparison, International Conference on Space Optics - ICSO 2018
***doi: 10.1117/12.2312099 Scattering from reflective diffraction gratings, Invited paper SPIE Optical Systems Design 2018
****doi: 10.1117/12.2296071 Tackling sun intrusion: a challenge of close collaboration of thermal, mechanical, structural and optical engineers, International Conference on Space Optics - ICSO 2016