Teams competing in this year’s Space Elevator Games are sure to beat a path to the DILAS booth at the Photonics West Exhibition. Both USST and Lasermotive, the two laser-powered teams in the 2007 Space Elevator Games, used Laser Diode products from DILAS to power their climber and many more are certainly considering using them this year.
Dr. Georg Treusch from DILAS has kindly consented to answer a few questions for the Space Elevator Blog:
Space Elevator Blog [SEB]:Before being approached by USST and Lasermotive, were you aware of the concept of the Space Elevator?
[Dr. Treusch]: Yes, I have been in contact with Brad Edwards since the Games in Albuquerque.
[SEB]: What do you think of the idea of a Space Elevator?
[Dr. Treusch]:Very challenging to accomplish. In general it is a very good idea and at the same level and beneficial for the world as the solar car competition in Australia which will lead us away from burning our resources.
[SEB]: What are you and DILAS offering this year to teams who want to use your equipment?
[Dr. Treusch]: We are talking right now to more than 5 teams about using our new design which has to be finalized after we have solicited all needs from the teams. It will be a 2.5kW base module with all the optics to generate the beam for the 1 km distance and a motorized optic to match the beam to the panel size at various distance.
[SEB]: In the 2007 Games, both USST and Lasermotive used DILAS laser diodes. For the uninitiated (including myself), what is the difference between a “laser diode” and a “laser”?
[Dr. Treusch]: A laser typically generates one beam with high brightness using a gain medium and two mirrors. A laser diode does the same on a miniature scale. The emitting area is about 1 um high and typically 50 – 200 um wide the cavity length (distance between the mirrors) is about 1 – 3 mm with an output power of 3-5W. To get to more power those emitters are arranged on a laser diode bar (10mm wide, up to 50 emitter) with >100W power. The bars are mounted on high efficient heat-sinks which can be stacked for even more power. By combining multiple emitters the power can be increased but not the brightness. A fiber laser or disk laser with > 1kW power may have a beam quality of less than 3 mmxmrad (beam size x divergence) whereas the diode laser stack has a 10x higher value and therefore a lower brightness.
[SEB]: Telling us as much as you can divulge, how would you compare the approaches between Lasermotive and USST in using DILAS equipment?
[Dr. Treusch]: USST used the approach for an optimized optical system for the maximum distance required and matched the beam size at lower altitudes to the panel with optics. Lasermotive used stacks with lower brightness and did spread out the beam already at ground level (more optics needed and hard to control and to keep the stacks protected).
[SEB]: I know you attended last year’s Space Elevator Games. Are you planning on attending the Games this year too?
[Dr. Treusch]: For sure and I will be available at the Photonics West show in San Jose next week at our booth #6073.
Thank you Dr. Treusch!