FEATURE OPTICAL MODELLING
large source.” And, sometimes, what customers are trying to do is physically not possible.’ The next step is to identify and model the LED light source that will be used in the system. ‘The most important thing about getting accuracy in an illumination system is how accurately you model the sources,’ said Dr Mark Nicholson, vice president of the Zemax Group within Radiant Zemax. ‘We use a goniometer, which photographs a light source such as an LED from all angles. That builds up the three-dimensional radiance of that source in both the near field and the far field. The measured source model can then be used directly in the software.’ Then, everything that the emitted light will interact with in the surrounding area is measured. For example, if a company is re-designing its office lighting with LEDs, the workplace is modelled by the software to analyse how the emitted light will be distributed. ‘We build models of the room with the right dimensions and we have everything in the room characterised, so we understand how they scatter light,’ explained Pfisterer. ‘I have a box here from a company with several ceiling tiles, floor tiles, and paint samples. Once we have
Light distribution from an LED light source is simulated within Photon Engineering’s FRED software
characterisation data, we then build the model and predict the room lighting from there.’ Programmes such as TracePro from Lambda
Research, LightTools from Synopsys, FRED from Photon Engineering, and OpticStudio 14 from Zemax, use ray-tracing simulations to model how light travels through an optical system and how it interacts with different materials. ‘If [the rays] hit a mirror they just reflect; if they hit something
made of plastic, they refract [change their angle],’ according to Nicholson. ‘And, if there are rays of different wavelengths, they get bent by different amounts because the materials have different properties at different wavelengths.’ After the software has visualised the results of the proposed lighting system, decisions can be made as to whether the desired outcome has been achieved. If modifications are needed, this is where the design stage comes into play: a process known as optimisation. ‘If you imagine you have a source and detector, and some sort of mirror that is reflecting the light, you might want to try bending the mirror into different shapes and seeing what happens until you reach the desired goal,’ explained Nicholson. Optimisation can be carried out by hand by manually perturbing the parameters; however it is usually carried out automatically by the software itself. ‘You can tell the software what it is you want it to achieve, and then the software can go through the process of adjusting all of the parameters of the system in order to get the optical system that best meets your needs,’ he added. Although existing software can carry out design optimisation with minimal input from the
➤
Turn light years into light seconds.
If you’re not using FRED Optical Engineering Software from Photon Engineering in your prototype design-build process then, frankly, you’rewasting precious time.
FRED is the most flexible, accurate and fastest optomechanical design and analysis tool available. FRED streamlines the design-build process, eliminating the need to develop multiple prototypes by helping you get it right the first time, every time.
So get more done, more quickly and with less effort. Get to know FRED from Photon Engineering.
Learn all the ways FRED can speed up your optomechanical design and analysis projects. Contact Photon Engineering today.
FRED — the right solution every time. Coherent beam propagation • Stray light analysis • Illumination and non-imaging optical design • Imaging system analysis •Multi-wavelength characterization • Thermal imagery
520.733.9557 440 S.Williams Blvd., Suite 106 Tucson, Arizona 85711
www.photonengr.com
Photon Engineering
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41