There are three main imaging modes, each suitable for different types of assay. Below they are briefly described. You can select multiple light presets at the same time

Bottom light

Bottom light petri dish example (same as below)

Only works with the white, translucent trays. Gives an even, diffuse light from the bottom of the machine. This mode is optimal for most types of samples. It’s available in a “low” exposure mode for very transparent media, and the default mode, “medium”, which provides perfect illumination for a wide variety of common plate types.

Top light

Top light petri dish example (same as above)

The top light uses a ring light around the camera head itself, and illuminates the plates from the top. This is available in three different exposure levels, “low”, “medium” and “high” to span a wide spectrum of sample types. Each image is taken and pre-processed using a proprietary algorithm to reduce reflections as much as possible.

The top light works with white or black trays. It provides great capturing of surface morphologies and colours, but is also sensitive to reflections and various lighting artefacts, especially on microtiter plates. We recommend always using the top light among with the “medium bottom light” preset to use as a reference image in case there are reflections.

Fluorescence

The fluorescence imaging modes are the most advanced mode of imaging offered by the system, and requires purchase of the fluorescence module.

Fluorescence imaging should be used with black trays. It uses the top lighting hardware, but only one wavelength of illumination at a time. On top of this, it has an emission filter which filters out light outside the excitation spectrum before it reaches the camera.

The final output should be similar to a regular image, except there should be very little light from anything except those areas of the plate that contain the fluorescent proteins. You can see some examples and more specifications of the fluorescence module here.

The signal after imaging can be very low, but the signal to noise ratio can still be very good. In these cases, the fluorescence image will simply look black when viewed in the user interface if imaged with the standard fluorescence presets. In these cases, we offer a preset that automatically boosts the signal, which can be found under the “advanced presets” menu when starting a job.

We can perform quantitative analysis of the fluorescence signal – this method is not necessarily linear, and to get accurate absolute results, a fluorescence reference ladder is required. Relative results can still be obtained accurately as long as they are imaged with the same exposure offset.

Because it can be very difficult to troubleshoot fluorescence signal if no other images are taken, we highly recommend taking a regular toplight image along with the fluorescent image to confirm that there is growth on the plate at the timepoint of interest.