Prosecution Insights
Last updated: April 19, 2026
Application No. 18/059,799

Millimeter-Wave Directed-Energy Excavation

Non-Final OA §103
Filed
Nov 29, 2022
Examiner
SINGH, SUNIL
Art Unit
3678
Tech Center
3600 — Transportation & Electronic Commerce
Assignee
Massachusetts Institute Of Technology
OA Round
1 (Non-Final)
67%
Grant Probability
Favorable
1-2
OA Rounds
2y 8m
To Grant
92%
With Interview

Examiner Intelligence

Grants 67% — above average
67%
Career Allow Rate
742 granted / 1103 resolved
+15.3% vs TC avg
Strong +24% interview lift
Without
With
+24.5%
Interview Lift
resolved cases with interview
Typical timeline
2y 8m
Avg Prosecution
23 currently pending
Career history
1126
Total Applications
across all art units

Statute-Specific Performance

§101
1.9%
-38.1% vs TC avg
§103
42.3%
+2.3% vs TC avg
§102
23.0%
-17.0% vs TC avg
§112
29.5%
-10.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1103 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Election/Restrictions Claims 19,20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected Invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 12/16/2025. Specification Applicant is reminded of the proper language and format for an abstract of the disclosure. The abstract should be in narrative form and generally limited to a single paragraph on a separate sheet within the range of 50 to 150 words in length. The abstract should describe the disclosure sufficiently to assist readers in deciding whether there is a need for consulting the full patent text for details. The language should be clear and concise and should not repeat information given in the title. It should avoid using phrases which can be implied, such as, “The disclosure concerns,” “The disclosure defined by this invention,” “The disclosure describes,” etc. In addition, the form and legal phraseology often used in patent claims, such as “means” and “said,” should be avoided. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1-11, 14, 16, and 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ouellet et al. (US 2009/0321132) in view of Woskov et al. (Woskov Annual Report) . Regarding Claim 1, Ouellet et al. discloses a system for excavating earthen material (A drill bit system, abstract), the system comprising: a millimeter-wave (MMW) source configured to generate and output MWW radiation (A microwave assembly 12 includes a magnetron 28 which may produce electromagnetic energy at a frequency between 300MHz to 300GHz (999mm-0.99mm), para. [0018,0020]); and a transmission line, coupled to the MMW source (A transmission line comprised of a series of waveguides 22 is connected to the microwave assembly 12, para. [0017]), to guide the MMW radiation to an excavation site having the earthen material and to launch the guided MMW radiation as an excavation beam from a distal end of the transmission line into the earthen material (Waveguides 22 transfer the microwave energy to an excavation bit 18 which excavates a shaft 26 in the aggregate 20, which may be rock, para. [0017], [0023]), wherein the MMW source and the transmission line are configured to deliver the MMW radiation in the excavation beam to the excavation site such that the earthen material at the excavation site is at least fractured by the excavation beam (The electromagnetic energy is capable of inducing fractures in the aggregate, para. [0007], [0064]), and wherein the MMW source and/or the transmission line are further configured to move the distal end of the transmission line in a first direction that is perpendicular to a second direction in which the excavation beam propagates to the excavation site (The distal end of the waveguide 223 is provided with an antenna 48. The waveguide 22 and antenna rotate about the Z axis, moving in a plane orthogonal to the downward direction in which the beam proprogates para [0038-0040]). Ouellet et al. discloses the invention substantially as claimed. However, Ouellet et al. fails to explicitly disclose wherein a free-space wavelength of the radiation is from 0.1 millimeter (mm) to 30 mm and the MMW source and the transmission line are configured to deliver at least 10 kW/ cm2 of the MMW radiation. Woskov et al. (Woskov Annual Report) is in the field of millimeter wave drilling (page 1, para. 1) and teaches wherein a free-space wavelength of the radiation is from 0.1 millimeter (mm) to 30 mm (The feasibility of rock drilling at frequencies of 30 to 300 GHz (0.99-9.99 mm) has been investigated, page 1, para. [0001]; A 28 GHz (10 mm) turn key gyrotron system has been delivered to the PSFC under a long term loan agreement that includes use for research of enhanced geothermal systems, page 6, para. 3) and the MMW source and the transmission line are configured to deliver at least 10 kW/cm2 of the MMW radiation (Figure 3 shows that for a lMW beam power, the average power density for boreholes with a diameter less than 10 cm is greater than 10 kW/cm2). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the system of Ouellet et al. to include a free-space wavelength of the radiation from 0.1 mm to 30 mm and an MMW source and the transmission being configured to deliver at least 10 kW/cm2 of the MMW radiation as taught by Woskov et al. since such a motivation would have been to select a wavelength and power density that best fractures the earthen material for a desired size of borehole. Regarding Claim 2, Ouellet et al. (as modified above) discloses the invention substantially as claimed. However, Ouellet et al. (as modified above) fails to explicitly disclose wherein the MMW source and the transmission line are further configured to deposit a majority of energy from the excavation beam into the earthen material to a depth from 0.1 cm to 20 cm. However, Ouellet et al. does disclose that the depth of material being irradiated should be kept small (Only a relatively small depth D is being irradiated at any one time, reducing the required power of electromagnetic energy, para, [0157]). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to deposit a majority of energy from the excavation beam into the earthen material to a depth from 0.1 cm to 20 cm, since discovering the optimum value of a result effective variable involves only routine skill in the art. The motivation would have been to direct the radiation at a confined area in order to achieve a desired power density with a given beam power. Further, Ouellet et al. (as modified above) fails to explicitly disclose wherein the MMW source and the transmission line are further configured to deposit a majority of energy from the excavation beam into the earthen material in an area greater than 1 cm2 but not greater than 100 cm2. However, Woskov et al. (Woskov Annual Report) discloses depositing a majority of energy from the excavation beam into the earthen material at the excavation site in an area greater than 1 cm2 but not greater than 100 cm2 (A 5 cm diameter wellbore could be penetrated at 50 m/hr with 1 MW of power, which may be provided by a gyrotron, page 5, para. 3-5). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to include depositing a majority of energy from the excavation beam into the earthen material at the excavation site in an area greater than 1 cm2 but not greater than 100 cm2 as taught by Woskov et al. (Annual Report). The motivation would have been to achieve a bore of the desired size. Regarding Claim 3, Ouellet et al. discloses mechanical apparatus to remove the earthen material fractured by the excavation beam from the excavation site (The drill rod 16 provides an avenue for removing rock chips, dust and other debris, which would otherwise accumulate at the bottom surface 42 of the shaft 26 during excavation, para. [0026]). Regarding Claim 4, Ouellet et al. discloses wherein the mechanical apparatus is configured to produce pressurized gas to blow at least a portion of the earthen material fractured by the excavation beam and/or melted earthen material from the excavation site (The debris removal is accomplished by passing pressurized air through the drill rod 16 and through the excavation bit 18, forcing air out of the shaft 26, para. [0026]). Regarding Claim 5, Ouellet et al. discloses wherein the transmission line further comprises at least one moveable portion to scan the excavation beam laterally and/or vertically with respect to the earthen material without moving the MMW source (The distal most portion of the waveguide 22 is offset from the rotational axis Z so that it can rotate with the drill bit 18, para. [0032], [0040], figure 6a; Adapter 36 is rotary, so that magnetron 28 can remain stationary while waveguide 22 rotates with the excavation bit 18, para. [0025]). Regarding Claim 6, Ouellet et al. (as modified above) fails to explicitly disclose wherein the MMW source is further configured to output the MMW radiation in a series of pulses. However, Woskov et al. (Woskov Annual Report) is in the field of millimeter wave drilling (page 1, para. 1) and teaches wherein the MMW source is further configured to output the MMW radiation in a series of pulses (Experiments with short pulse gyrotron beam air breakdown show that power densities at one atmosphere pressure need to be over 1 MW/cm2 for plasma breakdown. Though this breakdown threshold would decease with continuous operation, it would also increase with the higher pressures that would be found in deep wells, page 5, para. 3). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to include wherein the MMW source is further configured to output the MMW radiation in a series of pulses as taught by Woskov Annual Report. The motivation would have been to avoid plasma breakdown that would slow the forward penetration rate. Regarding Claim 7, Ouellet et al. discloses: a gas inlet coupled to the transmission line to inject a gas into the transmission line (A swivel 38 is coupled to waveguide 22 and transports drilling fluid, such as pressurized air, from reservoir 40 to drill rod 16 around cable 22, para. [0026], figure 2); and sealing apparatus to seal the distal end of the transmission line to the excavation site such that the excavation site can be pressurized (It is preferable to include an adapter seal which prevents the high pressure air from leaking around the waveguide 22, para. [0027]). Regarding Claim 8, Ouellet et al. discloses a mirror to focus the excavation beam from the distal end of the transmission line onto the excavation site (A conical reflector 60 reflects electromagnetic energy from the end of the waveguide 22 into the drilling environment, para. [0038]). Regarding Claim 9, Ouellet et al. discloses wherein the distal end of the transmission line is tapered from a larger diameter to a smaller diameter at the distal end (Waveguide 22 is stripped down to the inner conductor 68 at its distal end, para. [0037]). Regarding Claim 10, Ouellet et al. discloses a method of excavating earthen material (A drill bit system, abstract), the method comprising: generating, with a millimeter-wave (MIW) source, MMW radiation (A microwave assembly 12 includes a magnetron 28 which may produce electromagnetic energy at a frequency between 300MHz to 300GHz (999mm-0.99mm), para. [0018,0020]); coupling the MMW radiation to a transmission line (The microwave assembly 12 and the drilling assembly 14 are interconnected by a transmission line comprised of a series of waveguides as in 22, para. [0017]); guiding, with the transmission line, the MMW radiation to an excavation site having the earthen material (The waveguide 22 transmits the output of the magnetron 28 to the drill bit 18, para. [0018], [0022]); forming an excavation beam from the MMW radiation at a distal end of the transmission line (The microwave energy is used to reduce the strength of the aggregate 20 and improve the efficiency of the excavation bit 18, para. [0020]); illuminating the earthen material at the excavation site with the excavation beam (The microwave energy is transmitted to drill bit 18 where it is directed downward into the borehole, para. [0024], [0038]); fracturing the earthen material at the excavation site with the excavation beam (The electromagnetic energy is capable of inducing fractures in the aggregate, para. [0007], [0064]); and removing, with mechanical apparatus, the earthen material fractured by the excavation beam from the excavation site (The debris removal is accomplished by passing pressurized air through the drill rod 16 and through the excavation bit 18, forcing air out of the shaft 26, para. [0026]). Ouellet et al. discloses the invention substantially as claimed. However, Ouellet et al. fails to explicitly disclose the radiation having a free-space wavelength from 0.1 millimeter (mm) to 30 mm and illuminating the earthen material with an irradiance of at least 10 kW/cm2. However, Woskov et al. (Annual Report) is in the field of millimeter wave drilling (page 1, para. 1) and teaches the radiation having a free-space wavelength from 0.1 millimeter (mm) to 30 mm (The feasibility of rock drilling at frequencies of 30 to 300 GHz (0.99-9.99 mm) has been investigated, page 1, para. [0001]; A 28 GHz (10 mm) turn key gyrotron system has been delivered to the PSFC under a long term loan agreement that includes use for research of enhanced geothermal systems, page 6, para. 3) and illuminating the earthen material with an irradiance of at least 10 kW/cm2 (Figure 3 shows that for a lMW beam produced by a gyrotron, the average power density required to drill a borehole with a diameter less than 10 cm is greater than 10 kW/cm2). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Ouellet et al.to include the radiation having a free-space wavelength from 0.1 mm to 30 mm and an irradiance of at least 10 kW/cm2 as taught by Woskov et al. (Annual Report), since discovering the optimum value of a result effective variable involves only routine skill in the art. The motivation would have been to adapt the system to more effectively fracture material (better penetration) with the electromagnetic beam. Regarding Claim 11, Ouellet et al. (as modified above) discloses the invention substantially as claimed. However, Ouellet et al. (as modified above) fails to explicitly disclose the method further comprising: depositing a majority of energy from the excavation beam into the earthen material at the excavation site to a depth from 0.1 cm to 20 cm into the earthen material. However, Ouellet et al. does disclose that the depth of material being irradiated should be kept small (Only a relatively small depth D is being irradiated at any one time, reducing the required power of electromagnetic energy, para, [0157]). It would have been considered obvious to one of ordinary skill before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to deposit a majority of energy from the excavation beam into the earthen material to a depth from 0.1 cm to 20 cm, since discovering the optimum value of a result effective variable involves only routine skill in the art. The motivation would have been to direct the radiation at a small area in order to achieve a desired power density with a given beam power. Ouellet et al. (as modified above) fails to explicitly disclose the method of depositing a majority of energy from the excavation beam into the earthen material at the excavation site in an area greater than 1 cm2 but not greater than 100 cm2. However, Woskov et al. (Annual Report) is in the field of millimeter wave drilling (page 1, para. 1) and teaches depositing a majority of energy from the excavation beam into the earthen material at the excavation site in an area greater than 1 cm2 but not greater than 100 cm2 (A 5 cm diameter wellbore could be penetrated at 50 m/hr with 1 MW of power, which may be provided by a gyrotron, page 5, para. 3-5). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to include depositing a majority of energy from the excavation beam into the earthen material at the excavation site in an area greater than 1 cm2 but not greater than 100 cm2 as taught by Woskov et al. (Annual Report) since such a motivation would have been to achieve a bore of the desired size. Regarding Claim 14, Ouellet et al. discloses the method of moving the distal end of the transmission line with respect to the earthen material without moving the MMW source (The distal most portion of the waveguide 22 is offset from the rotational axis Z so that it can rotate with the drill bit 18, para. [0032], [0040], figure 6a; Adapter 36 is rotary, so that magnetron 28 can remain stationary while waveguide 22 rotates with the excavation bit 18, para. [0025]). Regarding Claim 16, Ouellet et al. discloses the method of reflecting the excavation beam from a mirror to focus the excavation beam at the excavation site (A conical reflector 60 reflects electromagnetic energy from conductor 68 into the drilling environment, para. [0038]). Regarding Claim 17, Ouellet et al. discloses the method of removing the earthen material fractured by the excavation beam comprises blowing at least a portion of the earthen material fractured by the excavation beam and/or any melted earthen material from the excavation site with pressurized gas (A pressurized air flow through the drill rod 16 is used to clear debris from around the excavation bit 18 and out of the excavation shaft 26, para. [0026]). Claim(s) 15,18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ouellet et al. ‘132 in view of Woskov et al. (Woskov Annual Report) as applied to claim 10 above, and further in view of Shnell (US 20140041940). Regarding Claim 15, Ouellet et al. (as modified above) discloses the invention substantially as claimed. However, Ouellet et al. (as modified above) fails to explicitly disclose the method further comprising: forming a trench in the earthen material with the excavation beam; inserting a hydraulic device into the trench; and breaking a portion of the earthen material from the trench with the hydraulic device. However, Shnell is in the field of microwave drilling (abstract) and teaches forming a trench in the earthen material with the excavation beam (Drilling part of the borehole using microwaves to make part of the rock liquid, para. [0062]); inserting a hydraulic device into the trench (Directing fluid jets toward the rock within the borehole, para. [0062]); and breaking a portion of the earthen material from the trench with the hydraulic device (Cutting or blasting the molten rock into droplets that are subsequently cooled into pebbles and carried away by the fluid, para. [0062]). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to include forming a trench in the earthen material with the excavation beam; inserting a hydraulic device into the trench; and breaking a portion of the earthen material from the trench with the hydraulic device as taught by Shnell since such a motivation would have been to more effectively remove material from the borehole. Regarding Claim 18, Ouellet et al. (as modified above) discloses the invention substantially as claimed. However, Ouellet et al. (as modified above) fails to explicitly disclose the method further comprising delivering an additive to the excavation site to modify a viscosity of melted earthen material flowing at the excavation site. However, Shnell teaches delivering an additive to the excavation site to modify a viscosity of melted earthen material flowing at the excavation site (Rock melted by microwaves is blasted by a fluid that cools the melted rock so that it is solidified into pebbles and can be subsequently removed from the borehole, para. [0062]). It would have been considered obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Ouellet et al. (as modified above) to include delivering an additive to the excavation site to modify a viscosity of melted earthen material flowing at the excavation site as taught by Shnell since such a modification would have been to more effectively remove material from the borehole. Allowable Subject Matter Claims 12,13 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to SUNIL SINGH whose telephone number is (571)272-7051. The examiner can normally be reached M-Th 8-3, F 9-8 and 2nd Sat 11-7. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Amber Anderson can be reached at 571 270 5281. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /SUNIL SINGH/Primary Examiner, Art Unit 3678 SS 2/7/2026
Read full office action

Prosecution Timeline

Nov 29, 2022
Application Filed
Feb 07, 2026
Non-Final Rejection — §103
Mar 03, 2026
Applicant Interview (Telephonic)
Mar 06, 2026
Examiner Interview Summary

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Prosecution Projections

1-2
Expected OA Rounds
67%
Grant Probability
92%
With Interview (+24.5%)
2y 8m
Median Time to Grant
Low
PTA Risk
Based on 1103 resolved cases by this examiner. Grant probability derived from career allow rate.

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