Light Field Capture- 1 min
Lytro recently released the first consumer “light field camera.” This means that the camera not only captures what position each light ray hits the sensor, but also the angle of each light ray. Imagining what a light field is, why this data is useful, and how it is transformed can be a difficult hurdle to overcome. Once it is understood, light fields can be really useful. I added a light field sensor to my Optic Workbench application, and explored using that sensor to capture information about a difracting surface.
While a photograph has 4 dimensions (x, y, intensity, color), a light field of the same scene has 6 dimensions (x, y, Θ1, Θ2, instensity, color). That is a lot of information! Optics Workbench works with 2 dimensonal scenes, which are easier to manage. A “photograph” in this 2D environment has 3 dimensions (x, intensity, color), and a light field has 4 dimensions (x, Θ, intensity, color). Mapping Θ to the y-axis, and this can be visualized in a graph.
You can try this out for yourself in Optic Workbench. The sensor is the component with a white side and a black side. The white strip captures light rays. Clicking on the sensor shows the light field graph. Notice how the graph is transformed when you move or rotate the sensor. You can apply these transformations digitally after the light field is captured. For example, digitally moving the sensor to refocus the image. This is what the Lytro has done.