Our mirrors consist of a reflective membrane placed over concentric electrode rings. Electrostatic actuation of the mirror surface is accomplished by applying a voltage between the membrane and the electrodes underneath. The focal length can varied from infinity (flat mirror) to less than 60mm, with full stroke settling times of less than 100µs. Our standard mirror diameter is 4mm, with other diameters available by request.
With a step response time less than 200µs, Revibro’s tunable mirrors are orders of magnitude faster than other z-stack actuators. Focus stepping can be accomplished during the retrace time of a galvo, meaning no delay is necessary before the next image in a stack. Stacks and volumes can be acquired at full video rate – limited only by the speed of the X-Y scanners.
The impact on imaging is significant. With ScanImage, a “sawtooth” scan type is no longer necessary to mitigate step jitter, as is the case with piezo-based actuators. The “step” scan type works directly. Additionally, all delays (flyback time, actuator lag) can be set to zero resulting in real-time volume acquisition.
The video below shows a stack capture of a pollen grain. The frame rate is 30Hz using a galvo-resonant scan head. Because the z-scanner requires no delay, the full volume can be acquired using the 30Hz base frame rate.
The video below shows the performance of Revibro’s tunable mirror jumping between image planes. The fast-z actuator was stepped between locations of 0µm, 15µm, and 30µm, with a return to 0µm at the end of every volume. This corresponds to the top, middle, and bottom of the pollen grain shown in the left, middle, and right images respectively. 100 volumes were captured. Because the “step” waveform type is used with no delays, the effective frame rate is 10fps/depth.
Our mirrors are available with up to five separate concentric electrodes, allowing shape of the mirror surface to be fine-tuned with a separate actuation voltage applied to each zone. The result is the ability to tune out spherical aberration in the optical system. Because the surface shape can be changed extremely quickly, real time aberration corrections can be performed to remove sample induced aberrations that change with focal position.
Laser focus control
Compact, high-speed imaging
Our team at Revibro has expertise in optical and mechanical system design, micromachining, and system integration.
Office: 670 S. Ferguson Ave., Suite 3 Bozeman, MT 59718