| 摘要 |
<p>A photothermal apparatus is provided for controllably heating and cooling a gas in order to alter and thereby control the acoustic, mechanical or optical properties of the gas. For acoustic applications, the photothermal device may be used to heat and cool the gas in order to generate three-dimensional spatially-located sound corresponding to an electrical audio signal (102, 104, 106). Also, the photothermal device may be used to generate a three-dimensional sound shield around a noise source in order to prevent the propagation of sound waves from the noise source. It may also be used to controllably heat and cool a gas to thereby provide mechanical energy or force for moving an object.</p> |
