Robotic Imagers can be very similar or very different to Human eyes,
The eye is made up of many parts, as is the camera.
The Cornea that protects the eye – Cameras often have a protective transparent cover to protect them from liquid or dust (Even the Mars Curiosity rover during decent through the Martian atmosphere)
The Pupil of the eye allows light to enter, the Iris muscles control the size of the pupil to control how much can enter. – Cameras have apertures that do the same thing, controlling the amount of light that enters the camera. The Iris is also coloured and makes the human eye so interesting to look at, what colour is the Iris’ of your eyes?
Both eyes and cameras have a Lens, these allow you to focus the light onto the retina of the eye or CCD of the camera, a single lens flips the image so the human brain or software connected to a camera must flip the image to make it right way up. in a camera that is not controlled by a computer then multiple lens can be used to correct this.
In order to see light an eye or camera must be able to detect it, this requires Photoreceptors. In humans this is called the Retina which contains two cells, Rods which mostly detect light intensity and Cones which are better at detecting colour. Try looking at colours in the day and at dusk, do you see any difference in reds and greens? Cones come in three types, Red, Green and Blue detectors which pick up those colours and the brain mixes them into the colours you see. – In a camera the Photoreceptor tends to be a CCD, this has pixels that are sensitive to different colours (like Cones in the eye) these pixels can just detect the intensity of light (like Rods) producing black and white images, or they can be made to detect specific colours.
The Optic Nerve takes the information from the Retina to the brain – In a camera a data cable connects to the CCD and takes the information to the computers CPU to be processed into an image, or for the data to be relayed to Earth for another computer to turn into an image.
Cleaning the eye is as simple as blinking, tear ducts provide the lubrication to remove grit or dirt from the protective cornea, however what about on Mars? There are a few tricks to clean a robotic camera lens, the most simple is to have a closable cover to protect the lens when the weather is blowing dust around, they can also point the camera at the floor much like you may do when walking along a beach on a windy day. Some cameras can use the planets atmospheric winds to try and remove particles on the lens. Finally their is the option to just let dirt sit there, automatic correction software can detect pixels with missing information and correct the image to fill in the gap.
Blow Deck Activity – 30 min set up time, 5 min activity
What do Pilots and Pirates have in common?
You will require an eyepatch for each participant, a darker room and a light room.
They both wear patches to be able to see in the dark. Light and Dark adaption take about half an hour to occur so anyone with a job (or criminal activity) that requires going from a bright place to a dark one will find that either they are blinded by the dark or that the intensity of the light is too painful to see clearly.
Now place the patch over one eye, be aware that it may be disorientating and the covered eye will be painful if exposed to bright light after the activity.
Now wait half an hour (no peeking it will delay the adaptation).
Move into a darker room and notice how difficult it is to see, then move the eye patch from the eye it currently covers to the other eye.
You should notice that you can see more clearly with this eye.
If you want repeat this in the lighter room.
Finally remove the patch, this may make you dizzy, but your vision will gradually return to normal. If you wish you could time how long this takes to see if it is quicker then half an hour.
Further Materials, Resources & Information
Below you will find more resources and external websites related to this lesson.
- www.arborsci.com – A simple observation made by Newton which you can replicate (carefully) with your own eyes.