Fido-Φ, or also known as Free-Fall, is a two-dimensional imaging fluorometer. It falls through the water column taking high-resolution images of the physical and planktonic microstructures that exists in our oceans. It's an autonomous, untethered instrument composed of a high sensitivity, low noise, thermo-electric cooled CCD camera (LUMIS) and a green (532 nm) laser. The laser light, spread as a thin sheet, is used to induce the chlorophyll from the microstructures, which lights as fluorescence. The camera is equipped with special filters to image this fluorescence. The imaging takes place 75 cm below the instrument and therefore in a completely undisturbed medium. The fall rate is ~10 cm/s (adjustable) and images are taken at 2-second interval and stored by the camera controller on its internal hard drive. The Field of view (FOV) is 32 by 32 cm with a 312 micron resolution. There is also sensor data that is saved by the sensor controller. Sensor readings include depth, speed, heading, pitch, roll, temperature, and humidity for all 3 housings (camera, laser, and sensor). The sensor controller also controls the laser and the depth at which the weight is released, set to 100 m, allowing the unit to get back to the surface. All data is downloaded via Ethernet once the unit is retrieved and on deck.