Case Study 6: Source/Object Split Through A Beam Splitter

Goal

This case study demonstrates a source/object workflow where the illumination source is not the Object row:

• load a right-angle beam-splitter illumination layout;

• verify that Src1 is an independent illumination source row;

• trace source light through a 45 degree beam splitter to an object target;

• follow the object-return path to a camera sensor;

• use Source Illumination Report to audit source throughput at both the object and camera targets;

• run a detector power map at the camera plane.

The screenshots in this tutorial are generated from the live Tk UI with:

python -m KrakenOS.UI.capture_right_angle_beam_splitter_case_study_screenshots

Load The Layout

1. Start the UI with python -m KrakenOS.UI.layout_editor.

2. Choose Layouts -> Beam Splitters / Folds -> Right-Angle Beam-Splitter Illumination.

3. Keep Trace mode = Non-Sequential Preview.

4. Keep NS probabilistic coating split off.

The first visible row is Src1. That row is a scene source, not a KrakenOS surface. The Object row is reference geometry only. In this preset, the physical source starts at (0, -80, 45) mm and points along +Y toward the 45 degree splitter.

Src1 launches the illumination. The Object row no longer has to be the ray source.

Read The Physical Paths

Click Update. The schematic shows the source entering from the side, the splitter sending the useful reflected branch to the object target, and the returning object branch transmitting toward the camera sensor.

The useful path is not a straight object-to-image sequential chain. It is a folded non-sequential source path.

Use Path View

After Update, open the table toolbar Path view dropdown and select:

Path 2: 45 deg 50/50 splitter coating to 45 deg 50/50 splitter coating via Object target (specular proxy)

This isolates the object-return leg. The current Object Target row is a specular proxy: it lets the beam return through the splitter and camera path. Use a Diffuse Object surface when the required physics is Lambertian or BRDF scattering rather than a mirror-like proxy.

The object-return path is separate from the source and camera legs.

Now select:

Path 4: 45 deg 50/50 splitter coating to Camera sensor via Splitter exit face, Camera arm clear aperture

This isolates the useful camera leg after the returning object branch passes through the splitter.

The camera path contains the splitter exit face, clear aperture, and Image sensor.

Audit Source Illumination

For the report screenshots, use:

Ray fan count = 121
Source radius [mm] = 8.0
Detector bins = 96
Path view = All paths

Choose Actions -> Source Illumination Report. Set Target to:

3: Object target (specular proxy)

The report verifies that source rays reach the object target and reports the power throughput after the first beam-splitter interaction.

Now change Target to:

5: Camera sensor

The camera report verifies that the object-return path reaches the Image plane. The lower throughput is expected because the useful path has passed through two 50/50 splitter interactions.

Run The Camera Detector Map

Set the analysis controls to:

Analysis path = Output: Detector output port
Analysis surface = 5: Camera sensor

Click DetMap and Update.

DetMap shows the final camera-plane power distribution for the useful source-to-object-to-camera path.

Run The Python Example

The same layout has a scriptable example:

python KrakenOS/Examples/Examp_Right_Angle_Beam_Splitter_Illumination.py

The script prints the source origin/direction and a per-ray trace summary, including whether each ray hits the object target and reaches the camera.

What This Proves

This case study exercises the source/object separation needed for inspection, projector, and coaxial-illumination workflows:

• the Source panel and Src1 scene row define illumination;

• the Object row is reference/object geometry, not the ray launcher;

• a 45 degree splitter can route illumination to the object;

• an object-return branch can pass back through the splitter to a camera;

• source-hit records preserve throughput and footprint diagnostics;

• detector analysis can be run on the resulting camera path.

Common Mistakes

I moved the Object row and expected the source to move.

Move the source controls or open Scene Source Manager. Object geometry and illumination source are separate scene entities.

I expected diffuse object scattering from Object Target.

Object Target is currently a specular reflective proxy in this preset. Use Diffuse Object examples for Lambertian or rough scattering.

The camera power is about half of the object-target power.

That is expected for this deterministic 50/50 splitter path. The useful beam reflects once to reach the object and transmits once to reach the camera.

Path view changed the visible rows.

Path view filters the table and plot. It does not renumber KrakenOS surface indices or convert source rows into surfaces.