Living Materials Herald a New Era in Soft Robotics

Living beings have an unsurpassed range of ways to manipulate objects and interact with them. They can make autonomous decisions and can heal themselves. So far, a conventional robot cannot mimic this complexity even remotely. Classical robots are often used to help with lifting and gripping and thus to alleviate the effects of menial tasks. Sensors can render robots responsive, and artificial intelligence aims at enabling autonomous responses. Inanimate soft robots are a step in this direction, but it will only be in combination with living systems that full complexity will be achievable. The field of biohybrid soft robotics provides entirely new concepts to address current challenges, for example the ability to self‐heal, enable a soft touch, or to show situational versatility. Therefore, “living materials” are at the heart of this review. Similarly to biological taxonomy, there is a recent effort for taxonomy of biohybrid soft robotics. Here, an expansion is proposed to take into account not only function and origin of biohybrid soft robotic components, but also the materials. This materials taxonomy key demonstrates visually that materials science will drive the development of the field of soft biohybrid robotics.     

Frequency stabilized ammonia laser system for probing the 24 THzclock transition of a trapped barium ion

The design, performance and frequency stability of an optically pumped ammonia laser operating on the sP(8,6) transition of ¹⁵NH₃ at 12.48 μm wavelength are discussed. The short term frequency stability was tested by heterodyning two similar lasers. An Allan deviation of 2·10^-11 for averaging times from 10^-4 s to 1 s was achieved for the free running laser. Absolute values of the laser frequency were obtained by measuring against the NRC H4 hydrogen maser standard with the help of the NRC frequency chain. A scan across a narrow fine-structure transition in a single trapped barium ion provided a final test for the overall stability     

Precision frequency measurement of the 2S1/2 2D5/2 transition of Sr+ with a 674-nmdiode laser locked to an ultrastable cavity

We have measured the frequency of the 5s ²S_1/2 -4d ²D_5/2 clock transition of a single Sr ion confined in a Paul trap. A diode laser locked to an ultrastable Fabry-Perot (F-P) cavity was used to probe the transition with a resolution of 3.5 kHz. The absolute frequency was determined from heterodyne measurements referenced to an iodine stabilized HeNe laser and a CO₂ laser yielding a value for the S-D transition of (444 779 043 963±30) kHz. This work could lead to the development of a new optical frequency standard at 674 nm     

Investigation of the optical behaviour of GaAs lasers operated with pulse and sinusoidal modulation

Investigation of the influence of pulse and sinusoidal modulation on the time-resolved laser spectra shows the existence of a time constant describing the optical transient behaviour. This time constant ranges from below 1 to more than 10 ns.     

Gain of high-pressure CO2lasers

Previous theories of high-pressure CO2gain spectra have been modified to include gain Contributions from the newly discovered 00°2 and 00°3 sequence bands. It is shown that the inclusion of these bands has important consequences for TE CO2lasers. At a pressure of 14 atm, the sequence bands typically cause a 40 percent increase in calculated gain at all frequencies. Even at pressures as low as 1 atm, the presence of the sequence lines leads to anomalous gain coefficients on many of the regular 00°1 laser lines.