April 2004 - Design Fair
We completed a 1m x 1m poster for the design fair which is geared towards educating other students about our research and to encourage future students to continue where we left off.

March 2004 - Presentation
Each team member had the opportunity to play a leadership role at different times throughout the project. I was in charge of ensuring the completion of the material design and lens design. I completed a powerpoint presentation on Microsoft Powerpoint outlining the milestones which I was in charge of. The presentation can be found here.

February 2004 - Testing on Lens Prototype
I developed testing procedures to characterize the prototype. With the help of the various optical testing books, some basic experiments were outlined. I have completed tests for effective focal length, focal points and conjugate focal points on our prototype lens and performed error analysis using sample variability and standard error calculations. Then, I created a list of optical equipment that we needed and found most of the equipment at the University of Toronto Optics Lab or at PRO (Photonics Research Ontario).

The first major decision was to determine which tests for the lens were necessary and which would only be done if time permitted. In optics, there are a wide range of experiments which could be performed on a compound lens. Each individual experiment can take several hours because all equipment positions must be precisely placed in order to obtain accurate results. I chose to test parameters which I designed for in my theoretical system. These included effective focal length, magnification, angular resolution, field of view, effective aperture and transmission %. Since we were now considering a compound lens system in a black box instead of single lenses, I also chose to test the principal planes (nodal points) and conjugate focal points of the system. Conjugate focal points help to define the way the lens transforms an object to its image plane. If these points are known along with the object and image distance, then the focal points of a lens can be found. The principal planes determine the point at which light becomes refracted from the lens. Since no lens can be an ideal thin lens with negligible thickness, there are two refracting surfaces for a lens (at the front side of the lens and at the back side). These points of refraction are known as the nodal points. Using these points, the thickness of a lens can be determined. Next, I had to determine the number of times each experiment would be repeated so that I could get more accurate results. In order to get as accurate a result as possible, the sample size should be large. Due to time constraints, however, I decided to repeat each experiment 5 times so that I would have enough samples to do proper error analysis.

January 2004 - Finalizing the Lens Design
The theoretical design of the optical system has been finalized using both hand calculations and ray tracing with CODE V software. An exoskeleton to hold the optical system has also been designed. A prototype lens similar to our theoretical design has been purchased after considering various cost vs. system tradeoffs.

December 2003 - Initial Lens Design
The project is currently in its optical design stage. All milestones which involved the researching of materials suitable for withstanding the extreme external conditions (severe temperature changes and radiation on Mars, vibration during launching) have been completed. We have done some initial designs for the optical system and we will soon be using CODE V (an optical design software) to design the optical telescope and to reduce aberrations in the lens system.

I began designing an optical lens system using geometric and Fourier optics. In order for the navigation team to be able to use the optical system, the system must have good resolution (so that two closely spaced objects can be resolved), provide sufficient field of view, and be light in weight. The system is also required to magnify a blur spot size to span several pixels and the image plane of the final lens must lie on the CCD pixel array. The power of the signal from the optical system must be at least 10 times the noise intensity of the CCD to provide a signal-to-noise ratio >= 10.
To start the design, the parameters of the lens system which were restricted by optical theory (ie. parameters which could not be changed) were determined first. One of these parameters was the lens diameter due to the required angular resolution and collecting power. After determining the diameter of the objective lens using the angular resolution provided, different optical configurations were evaluated in terms of size and functionality. An issue which I came across while designing for the magnification of the system was attempting to magnify the blurspot to span six pixels. On the image plane, however, the central bright spot seen by diffraction at a circular aperture (lens) is circular. When a circular blurspot is fit inside a square array (four pixels), the area used on the pixel array is maximized. If the blur spot were to fit into six pixels, there would be some area on the pixel array which is wasted. Therefore, I designed the magnification of the lens system to allow for one blurspot to span four pixels.

November 2003 - Material Selection
The initial stages of the project involved a lot of research on material and optical design. There are a number of resources with tables for different materials and their properties. Some of these tables were used by the other team members to select appropriate materials to create an athermal system. This prevents the movement of lens positions due to temperature changes; movements in position would result in optical performance degradation. I was required to use the property tables to select soft and durable material to protect the overall system during launching. In addition, I used the transmission tables for glass to design an optical filter to filter out undesired radiation. By filtering particular wavelengths of light and attenuating others, the light intensity passing through the optical system is limited, preventing well saturation in the CCD. When wells in the CCD saturate, electrons begin to overflow neighbouring wells, creating white streaks in the image.

September to October 2003 - Interface Specifications
In order to successfully design an optical system and build a working prototype, we will first need to identify and meet common interface specifications with the other teams that are working in conjunction towards the Mars Rover project. The navigation system has specific requirements (such as image span and resolution) that we should implement in our design. Our system will also need to match with the CCD�s physical and performance specifications that require our system to be a certain size and our image to fit within a certain number of pixels. The major challenge will be to match desired image outputs from the navigation system with the given parameters, set by the CCD. The next challenge will be to design our system to be suitable for Mars� environment. This will involve accounting for thermal expansions, vibrational disturbances, and degradation due to radiation exposure. Lastly, a working prototype must be built with a similar functionality to our theoretical design. Budget and time constraints will require us to make many system trade-offs to create an economical design.

We will be applying modern optical techniques (i.e. Geometric and Fourier optics) into our optical system design. For our optical system to survive the extreme conditions on Mars, we will need to do extensive research on material elongation, tensile strength, ambient variability (temperature) and robustness. In addition, to successfully design a functional system, weekly group meetings with the navigation and CCD teams will be conducted to ensure that the common interface specifications are being met, and to guarantee that solutions to common problems are implemented similarly in all teams. The Photonics Research of Ontario (PRO) will be providing us with a collimator to generate parallel rays of light (simulating light from stars) for testing. Also, PRO will be introducing us to modern design tools such as CODE V.