Stray Light

Stray light is unwanted light. It is light that leads to poor system performance and possibly product, or mission, failure. Stray light obscures faint signals, decreases the signal-to-noise ratio, reduces contrast, creates inaccurate radiometric, and photometric results, and in high-energy laser systems destroys optical elements and detectors. Stray light is caused by a number of phenomena including light scattered from optical and mechanical surfaces, ghost reflections from transmissive optical elements like lenses, edge diffraction from stops and baffles, unwanted diffraction orders from gratings, and thermal emission.

Managing Stray Light

Stray light analysis determines not only how unwanted light gets to your detector but also how much stray light makes it to the detector of your optical system. Stray light analysis allows you to examine if stray light is a problem and how to fix it during the design phase of the project before building your optical system. This prevents costly redesigns and potentially fatal design mistakes before tooling hardware.

The Most Advanced Optical Software

ASAP™ optical analysis software was developed in-house at Breault Research to meet the unique challenges of stray light analysis. Accurate and fast stray light calculations cannot be done with simple brute-force Monte Carlo calculations. That is why ASAP uses directed scatter methods to send scattered light towards the areas of most interest.

What you can do with ASAP

Identify stray light paths
Calculate their absolute and relative contributions
Determine if a system meets its requirements
Make design enhancements that improve system performance

Key ASAP Features for Stray Light Analysis

ASAP calculates stray light from scatter
ASAP models scatter within three-dimensional geometries
ASAP uses realistic BRDF models
ASAP calculates stray light from ghosts
ASAP does diffraction calculations
ASAP calculates thermal irradiance

Why ASAP is used for the toughest Stray Light Analysis Projects

To perform a first-order ghost analysis it is necessary for the software to track the paths of all of the ghosts. That is, a table of where the ghost reflections occur and how much power they contain is needed. ASAP has this capability.
To identify critical and illuminate objects, which is the first step in any scattered stray light analysis, it is necessary that rays be collected on all objects, not just a set of predefined "receivers". It is also necessary that the power collected by each object be tracked and tabulated. ASAP does both of these.
To perform an accurate quantitative analysis, it is necessary to have realistic BRDF models, not just Lambertian or "cosine to the nth" models. ASAP has 14 different classes of BRDF models, including the all-important Harvey model and the ability to fit or interpolate across measured data.
To perform even a simple quantitative stray light analysis, it is necessary to be able to direct scattered rays towards areas of interest. ASAP can do this.
Ghost's can sometimes be caused by total internal reflection (TIR) from lenses. ASAP can automatically switch from Fresnel reflections to TIR when the angle of incidence is high enough, and it properly calculates the flux of the ray as it does this.
Many optical systems use diffraction gratings, and the unwanted orders can cause stray light problems. ASAP can split one ray into many different orders.
It is often necessary to calculate beam footprints and arbitrary locations within a system to establish tolerances on apertures, baffles, housings, etc. ASAP can calculate such footprints anywhere within a system.
Occasionally it is necessary to identify a specific stray light path and graphically trace it back through the system to find out exactly how it propagates. In ASAP, users can select any arbitrary ray, set of rays, or stray light paths and ask for a three-dimensional graphical ray trace of this path.
ASAP is able to select subsets of rays based on stray light path, scatter order, flux, direction, position, etc. These subsets of rays can be used in irradiance or intensity calculations to identify the importance of a given class of stray light paths.

Pricing and Platform Information

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