| 摘要 |
<p>An imaging apparatus comprises an adaptive focus optical system, a digital image acquisition system, and an image analyser, and is arranged to set the focus of the optical system at a predetermined distance, acquire an image and pass the image to the image analyser, filter the image to identify an area containing an edge, analyse the sharpness of edge detail in that area, repeat a number of times using different focal distances, and identify a focal distance which corresponds to a peak image sharpness. A series of scans are therefore taken, one of which should correspond to an ideal distance or close thereto. Each scan is analysed for sharpness and the best can be selected. The adaptive focus optical system can include a reflective surface formed on a first conductive member spaced from a second conductive member and a means for applying a voltage across the two conductive members thereby to deform the first conductive member. The first conductive member is suitably silicon-based, such as silicon nitride, preferably with an aluminium surface layer. The second conductive member can be any suitable material, such as a surface of a printed circuit board. The mirror is preferably mounted at an angle to the horizontal (when in use) so as to cast an image towards the digital image acquisition system along an axis which is not directed towards the user.</p> |
