MClimber in the sun, array (right) and climber (left)

An early end. At approximately 12:10 am, the MClimber beam director fractured.

The MClimber Team

xxx

MClimber’s time in the sun turned out to be pretty short.

We got a good look at the array’s reflective properties using sun illumination, and while the array does give the appearance of a disco ball, all the reflections are very low quality (this is a good thing, as intended) and diverge very quickly. 

Before illuminating the array with the laser, since the tracking is manual, we rant the beam-director side melt test, pushing 8 kWatt through the optics. Regrettably, as we were passing the 4 kWatt mark, one of the mirrors cracked.

A quick post morten identified the culprit as a mirror retainer that was placed too far in and was thus illuminated. It heated up, and the thermal expansion pushed on the delicate mirror and fractured it.

This is not something the team could fix on the spot, and so the test was over. Since we’re contemplating a second testing period now, MClimber is not out of the ballgame, but they need to scramble to both fix the damage and complete the other parts that were not quite ready.

I hope to see them back soon – the system is obviously a result of long and hard work, and at a minimum it should get a chance to run to its potential rather than stay on the sidelines due to a mirror injury.

The MClimber team are (left to right):

• Andrew Lyjak
• Richard Chiang
• Casey Keys
• John Nees

MClimber Concentrator Pod

One array = 37 pods

MClimber's telescope gimbal, under construction

The University of Michigan’s MClimber team is back in force this year, with a very unique climber.

Following the lead of many solar applications, UofM chose to use concentrator PV modules – small, high-intensity-capable photovoltaic cells, and low-cost optics to capture as much light as possible and direct it onto the cells.

The beam director is pretty straight forward, built around a telescope gimbal. Controlled from a laptop, it is capable of performing the basic motions required. The tracking loop is not quite done yet, so during the test they’ll drive it manually.  This is not a problem, since we do not really require tracking – it is just desirable. As long as the system does not exceed the safety cone, they can perform lasing. 

The UofM climber design is modular. The first image shows a single concentrator “pod”, comprised of a Fresnel lens in the front, 4 reflective side panels forming a square-based pyramid, and a small 3×3 array of cells near the tip of the pod. The concentrator cells have a water based cooling system, since under the concentrated light, they will get to be pretty toasty.

As with all concentrating climbers, the optics on the climber have to point back towards the beam director, which requires a second tracking loop. Since the climber is unmanned, this loop cannot be driven manually, and I suspect that therein lies trouble. Luckily, this loop does not have to be as accurate as the main beam tracking loop.

MClimber will follow KCSP on the laser range, at around 10 am on Friday – stay tuned.