New zoom objective with deformable mirrors to make unmanned planes more efficient

Berlin, January 20 (ANI): Scientists have designed an all-reflective zoom objective with deformable mirrors for unmanned aerial vehicles (UAVs), which would enable the aircrafts to operate free of chromatic aberration.

The objectives in the on-board measuring equipment of a UAV must function free of chromatic aberration across a wide spectral range - from the ultraviolet region through the visible band and right up to the near and medium infrared range.

In such a scenario, conventional lens systems comprised of several lens elements are of limited use.

When required to image a wide spectral range, the image quality drops. Tthe image suffers from color fringing and becomes blurred.

Traditionally, specific lenses have been used for each different spectral band.

However, the difficulty is that UAVs can only carry a limited amount of weight.

Researchers, from the Fraunhofer Institute for Photonic Microsystems (IPMS) in Germany, are currently working to make it possible to capture images free from chromatic aberration in a number of spectral ranges using a single system.

This would have the advantage of prolonging the battery's life and increasing the aircraft's endurance.

According to Group manager Dr. Heinrich Gruger of the IPMS, "We've come up with a design for a new objective in which we've used mirrors instead of standard lens elements."

The objective is comprised of four mirrors, carefully arranged to avoid obscuration. This produces a higher-contrast image.

Two deformable mirrors take care of the triple zoom range - with no loss of image quality.

The new design eliminates the need for elaborate mechanical guides within the lens barrel.

Gruger believes that the new objective is potentially highly marketable.

"Both the automation technology sector and the automobile and equipment engineering sector would profit from this type of objective," he said.

Suitable deformable mirrors will have to be created, as conventional optical mirrors are rigid.

According to Gruger, "For the zoom function, we need mirrors that will permit flexible actuator control of the radius of curvature."

Optical simulations have shown that the mirrors would need to be at least 12 millimeters in diameter in order to produce a zoom objective with a sufficient f-number.

Nevertheless, the researchers have already been able to demonstrate the optical performance of the objective.

They built three identical setups with three different focal lengths in which the deformable mirrors were replaced by conventional rigid mirrors. (ANI)