System and method for laser downhole extended sensing

1. A laser drilling tool assembly, comprising:

a body that includes:

a first segment configured to receive an input beam from a laser source and couple the input beam to provide an irradiation beam to irradiate a downhole target, and

a second segment housing one or more purging pipes; and

a tool head that includes:

a retractable nozzle; and

one or more optical sensing elements mounted on the retractable nozzle, wherein when the downhole target is being irradiated by the irradiation beam, the retractable nozzle is extended towards the downhole target such that the one or more optical sensing elements are positioned closer to the downhole target, wherein the one or more optical sensing elements include an optical luminosity sensor, or a spectral sensor.

2. The laser drilling tool assembly of claim 1 , wherein the optical luminosity sensor comprises at least one of: a charge-coupled device (CCD) sensor, a complementary metal oxide semiconductor (CMOS) sensor, an avalanche photodiode (APD), or a photo diode (PD).

3. The laser drilling tool assembly of claim 1 , wherein the spectral sensor comprises at least one of: a scanning sensor, or a Fourier-transform infrared spectroscopy (FTIR) sensor.

4. The laser drilling tool assembly of claim 1 , wherein one or more optical sensing element include: coupling optical components configured to capture light signals emitted from the downhole target.

5. The laser drilling tool assembly of claim 4 , wherein the tool head further comprises a sensing cable,

wherein the light signals are transmitted, via the sensing cable, to an optical sensor that includes at least one of an optical luminosity sensor, or a spectral sensor, and

wherein the optical sensor is located outside the tool head, and

wherein the optical sensor is different from the at least one optical sensing elements mounted on the retractable nozzle of the tool head.

6. The laser drilling tool assembly of claim 5 , wherein the tool head further comprises wheels in the retractable nozzle,

wherein the wheels are configured to retract or extend the retractable nozzle, and

wherein the wheels are further configured to attach the sensing cable to the retractable nozzle.

7. The laser drilling tool assembly of claim 1 , wherein the tool head further comprises a sensor located at a tip of the tool head,

wherein the sensor is configured to measure an ambient temperature and a range between the tip of the tool head and the downhole target when the downhole target is being irradiated by the irradiation beam.

8. The laser drilling tool assembly of claim 1 , wherein the tool head further comprises:

a lens assembly to couple the irradiation beam to reach the downhole target.

9. The laser drilling tool assembly of claim 8 , wherein the tool head further comprises:

one or more internal purging nozzles mounted inside the lens assembly and configured to spray a flow of medium to merge with the irradiation beam.

10. The laser drilling tool assembly of claim 8 , wherein the tool head further comprises:

one or more external purging nozzles mounted outside the lens assembly and configured to purge debris from the downhole target being irradiated by the irradiation beam.

11. A method, comprising:

lowering an laser drilling tool assembly into a wellbore shaft in which a downhole target is located;

activating an irradiation beam that exits from a tool head of the laser drilling tool assembly;

extending one or more retractable nozzles on the tool head of the laser drilling tool assembly such that an optical sensing element mounted on the tool head is brought closer to the downhole target when the downhole target is being irradiated by the irradiation beam; and

collecting light signals emitting from the downhole target being irradiated by the irradiating beam.

12. The method of claim 11 , further comprising:

analyzing the light signals to characterize a rock type at the downhole target.

13. The method of claim 11 , further comprising:

retracting the one or more retractable nozzles when the light signals have been collected.

14. The method of claim 11 , further comprising:

measuring an ambient temperature and a range between a tip of the tool head and the downhole target when the downhole target is being irradiated by the irradiation beam.

15. The method of claim 14 , further comprising:

in response to the ambient temperature exceeding a first threshold, or the range falling below a second threshold, halting an extension of the one or more retractable nozzles.

16. The method of claim 15 , further comprising:

deactivating the irradiating beam.

17. The method of claim 11 , further comprising:

activating one or more internal purging nozzles mounted inside a lens assembly of the tool head to spray a flow of medium to merge with the irradiation beam.

18. The method of claim 11 , further comprising:

activating one or more external purging nozzles mounted outside a lens assembly of the tool head to purge debris from the downhole target being irradiated by the irradiation beam.