On this project, WMD designed and built the optomechanical hardware and a small environmentally sealed enclosure for a diode pumped laser. The system is intended to be deployed mounted to a helicopter, so the design also needed to be very rugged. The unit is 5.7 inches x 11.2 inches x 4 inches and can be customized with further development of the internal optical components and/or electronics.
During the design process, WMD determined that it was best to eliminate as many Risley wedges as possible. To meet that goal, we created custom differential screw adjusters that provide multi-axis lockable adjustment for the mirrors and optics.
Since the laser generates a large amount of heat, one of the requirements for this project was ample cooling capacity. This was accomplished with the use of dual Thermal Electric Coolers (TEC), dual fans, and a custom designed heat sink. The heat sink is inserted into a machined tunnel within the housing and air is forced through the tunnel and heat sink at a controllable rate. With this setup, we exceeded the cooling requirements. The heat sink, TECs, gain slab and diode are assembled as a separate module for easy removal and replacement.
To help isolate the system from warping and thermal expansion of the mating system, the unit is fitted with three custom-designed flexures.
Thermal control was a challenge on this project. We had a maximum volume to maintain and a laser that created a lot of heat inside a small space. To overcome this challenge, WMD designed an internal heat removal system that inserts a flow-optimized heat sink into an air tunnel machined through the lower half of the enclosure. Internally mounted fans force air through this tunnel at a controlled rate, providing excellent cooling. Our air flow design was lab tested and proven to surpass the minimum requirements.
The differential screw adjuster design that we created to replace Risley wedges has since been used in several other projects with excellent results.