| US 7,525,661 B2 | ||
| Laser photo-thermo-acoustic (PTA) frequency swept heterodyned lock-in depth profilometry imaging system | ||
| Andreas Mandelis, 3 Scarborough Heights, Toronto, Ontario M1M 2V3 (Canada); Alex Vitkin, 130 Glenlake Avenue, Toronto, Ontario M6P 1E5 (Canada); Sergey Telenkov, 108 Goodwood Park Crt., Apt.633, Toronto, Ontario M4C 2H2 (Canada); and Ying Fan, 2505-88 Bloor Street East, Toronto, Ontario M4W 3G9 (Canada) | ||
| Filed on Feb. 16, 2005, as Appl. No. 11/58,233. | ||
| Claims priority of provisional application 60/544969, filed on Feb. 17, 2004. | ||
| Prior Publication US 2005/0234319 A1, Oct. 20, 2005 | ||
| Int. Cl. G01B 9/02 (2006.01) | ||
| U.S. Cl. 356—432 [356/447; 356/237.1; 356/502] | 29 Claims |
| 1. A method to perform operator-controlled slice-by-slice photo-thermo-acoustic imaging of a material through a coupling fluid,
the method comprising the steps of:
(a) irradiating the material at a given point for a selected period of time with an excitation waveform from an optical excitation
source modulated by a linear chirp with frequency sweep producing frequency-swept modulation signals wherein frequency-swept
photo-thermo-acoustic signals are responsively emitted from said material;
(b) detecting said emitted frequency-swept photo-thermo-acoustic signals;
(c) repeating steps a) and b) while scanning across a surface of the material along a pre-determined line or across a two-dimensional
surface area of the material; and
(d) electronic signal processing to convert the emitted frequency-domain photo-thermo-acoustic signals into time-domain and
perform depth profilometric imaging at each point of the material while scanning to obtain thermoelastic and optical properties
of the material at various subsurface depths and producing a two-dimensional slice image of subsurface structures when the
scan is along said pre-determined line, or a three-dimensional volume image of subsurface structures when the scan is across
said two-dimensional surface area of the sample material.
|