# Light Tunnel Mk2 {% columns %} {% column %}

{% endcolumn %} {% column %} The Light Tunnel produces [**i.i.d.**](#user-content-fn-1)[^1] **data and images** from a controlled **optical experiment.** It contains a controllable light source, linear polarizers mounted on rotating frames, and sensors to measure light intensity at different frequencies and locations. A camera captures images from inside the tunnel. {% endcolumn %} {% endcolumns %} The chamber produces images and i.i.d. data from up to 99 variables, including sensor measurements, control inputs, and sensor parameters.

**Top right**: infrared-intensity measurements produced by the first sensor (`ir_1`) for different intensities of the light-source channels (`red/green/blue`). **Top left**: examples of images produced by the tunnel in the linked_leds (left) and the camera_fast (right) hardware configurations. **Bottom:** observing Malus' law in the effect of the polarizer positions (`pol_1, pol_2`) on the infrared intensity at the third sensor (`ir_3`).

Chamber diagram & variables

You can find a description of each variable in the documentation for each [hardware configuration](#hardware-configurations) below.

Right click to download the image (available under a CC BY-NC 4.0 non-commercial license).

Simulators

See the [Simulator Index](https://github.com/juangamella/causal-chamber-package/tree/main/causalchamber/simulators) for a list of the simulators we offer for this chamber, including documentation and example code.

### Hardware configurations Like all chambers, the wind tunnel can automatically load different [hardware configurations](/the-chambers/how-they-work.md#hardware-configurations). See the corresponding PDF for a chamber diagram, a complete description of all variables, and the causal ground-truth graph.

Name	Img. data	Description	Documentation	Causal ground-truth
`standard`	false	Standard configuration with all variables (excl. motor parameters).	.pdf	.pdf
`linked_leds`	false	Additional tunable causal effects.	.pdf	.pdf
`linked_leds_sigmoid`	false	Same as `linked_leds` but with tunable non-linear effects	.pdf	.pdf
`camera_fast`	true	Provides images and camera variables.	.pdf	.pdf
`led_matrix`	true	Same as `camera_fast` but with individual control of the light-source LEDs.	.pdf	.pdf

[^1]: i.e., independent and identically distributed observations given a fixed set of inputs, up to negligible effects like small sensor drifts --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.causalchamber.ai/the-chambers/light-tunnel-mk2-1.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.