Abstract

Hadamard mask encoding allows medium to high spatial resolution imaging with unfocused laser beams. A laser beam is imaged on the sample through a series of masks. The spatially encoded signals from each of <i>n</i> masks, each containing <i>n</i> resolution elements, are measured. The spatial distribution of the signal is recovered by Hadamard transformation of the matrix of encoded signals. Of course, the laser could be focused to an area equal to the unit resolution element. But, encoding with <i>n</i>-element masks reduces the power density at any point on the sample by a factor of <i>n</i>. We have already successfully employed masks containing 2<sup>8</sup> − 1 elements, and have estimated that it is feasible to use masks with 2<sup>10</sup> − 1 or even 2<sup>12</sup> − 1 elements. Reducing laser power density by a factor of 10<sup>3</sup> broadens the scope of spatially resolved laser spectroscopy and opens the possibility of Raman microscopy with pulsed lasers.

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription