Optomec’s Laser Engineered Net Shape (LENS™) Unit is a type of directed laser deposition (DLD) technology that was developed in the mid to late 1990’s as a spin-off company from Sandia National Laboratories. The Ohio State University purchased the very first unit from Optomec in 1997, and worked with Optomec on a series of technical upgrades to the unit over the next four years. The LENS™ is based on a principle similar to stereolography in that a near-net shape three-dimensional component can be produced by an additive manufacturing route, rather than a subtractive route. The LENS™ incorporates a Nd:YAG laser (nominally 550 W maximum) to melt a portion of a metal substrate. Metal powder (either liquid or solid, depending on many variables including the melting point, reflectivity, laser power, and time of flight in the laser) is injected into this molten pool creating a larger volume of material. The LENS and substrate move relative to one another, and the liquid metal solidifies at rates that approach those theoretically calculated for Rapid Solidication Processing (RSP). Typically, the LENS™ deposited material has an extremely refined microstructure with possible texture in the build direction. The system at The Ohio State University incorporates a dual-powder feeder design to affect compositionally graded material. Additionally, lots of research within CAMM is focused on exploiting elemental blends to produce a very large variety of compositions in a very rapid manner.

Laser: 
  Nd:YAG, 1.064 mm wavelength

Wattage available at substrate:
  100-550 W

Atmosphere:
  VAC Atmosphere Glove Box with atmosphere regeneration system
  Slightly positive pressure Argon atmosphere

Oxygen Sensor:
  Illinois Instrument, typical O2 levels: 1-15 ppm

Dimensional Information:      
  2.5 degrees of freedom (x-y- 1/2 z)

Build Window:
  1 cubic foot
  Linear encoder Parker Daedal Motors

Model name and number:
  LENS™ 750        

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2. Schwendner KI, Banerjee R, Collins PC, et al., "Direct laser deposition of alloys from elemental powder blends", SCRIPTA MATER 45 (10): 1123-1129 NOV 19 2001
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7. Collins PC, Banerjee R, Banerjee S, et al., "Laser deposition of compositionally graded titanium-vanadium and titanium-molybdenum alloys", MAT SCI ENG A-STRUCT 352 (1-2): 118-128 JUL 15 2003
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9. Banerjee R, Collins PC, Genc A, et al., "Direct laser deposition of in situ Ti-6Al-4V-TiB composites", MAT SCI ENG A-STRUCT 358 (1-2): 343-349 OCT 15 2003
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Other References of interest available in the literature

1. Wang, L; Felicelli, S; “Analysis of thermal phenomena in LENS™ deposition”, MAT SCI ENG A-STRUCT, 435: 625-631 NOV 5 2006
2. Ye, RQ; Smugeresky, JE; Zheng, BL; Zhou, YZ; Lavernia, EJ; “Numerical modeling of the thermal behavior during the LENS (R) process”, MAT SCI ENG A-STRUCT, 428 (1-2): 47-53 JUL 25 2006.
3. Susan, DF; Puskar, JD; Brooks, JA; Robino, CV, “Quantitative characterization of porosity in stainless steel LENS powders and deposits”, MATERIALS CHARACTERIZATION, 57 (1): 36-43 JUL 2006.
4. Liu, WP; DuPont, JN, “Direct laser deposition of a single-crystal Ni3Al-based IC221W alloy”, MET & MAT TRANS A-PHYS, 36A (12): 3397-3406 DEC 2005.
5. Rangaswamy, P; Griffith, ML; Prime, MB; Holden, TM; Rogge, RB; Edwards, JM; Sebring, RJ, “Residual stresses in LENS (R) components using neutron diffraction and contour method”, MAT SCI ENG A-STRUCT, 399 (1-2): 72-83 JUN 15 2005.
6. Liu, WP; DuPont, JN, “Fabrication of carbide-particle-reinforced titanium aluminide-matrix composites by laser-engineered net shaping”, MET & MAT TRANS A-PHYS, 35A (3A): 1133-1140 MAR 2004.
7. Unocic, RR; DuPont, JN, “Process efficiency measurements in the laser engineered net shaping process”, MET & MAT TRANS B-PROC, 35 (1): 143-152 FEB 2004
8. Rangaswamy, P; Holden, TM; Rogge, RB; Griffith, ML, “Residual stresses in components formed by the laser-engineered net shaping (LENS (R)) process”, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, 38 (6): 519-527 NOV 2003.
9. Liu, WP; Dupont, JN, “In-situ reactive processing of nickel aluminides by laser-engineered net shaping”, MET & MAT TRANS A-PHYS, 34A (11): 2633-2641 NOV 2003.
10. Unocic, RR; DuPont, JN, “Composition control in the direct laser-deposition process”, MET & MAT TRANS B-PROC, 34 (4): 439-445 AUG 2003.
11. Liu, WP; DuPont, JN, “Fabrication of functionally graded TiC/Ti composites by Laser Engineered Net Shaping”, SCRIPTA MATERIALIA, 48 (9): 1337-1342 MAY 2003.
12. Grylls, R, “Laser engineered net shapes”, ADVANCED MATERIALS & PROCESSES, 161 (1): 45-+ JAN 2003.
13. Miller, RS; Cao, G; Crujicic, M, “Monte Carlo simulation of three-dimensional nonisothermal grain-microstructure evolution: Application to LENS rapid fabrication”, JOURNAL OF MATERIALS SYNTHESIS AND PROCESSING, 9 (6): 329-345 NOV 2001.
14. Hofmeister, W; Griffith, M; Ensz, M; Smugeresky, J, “Solidification in direct metal deposition by LENS processing”, JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY, 53 (9): 30-34 SEP 2001.
15. Semiatin, SL; Kobryn, PA; Roush, ED; Furrer, DU; Howson, TE; Boyer, RR; Chellman, DJ, “Plastic flow and microstructure evolution during thermomechanical processing of laser-deposited Ti-6/Al-4V performs”, MET & MAT TRANS A-PHYS, 32 (7): 1801-1811 JUL 2001
16. Lewis, GK; Schlienger, E, “Practical considerations and capabilities for laser assisted direct metal deposition”, MATERIALS & DESIGN, 21 (4): 417-423 AUG 2000
17. Griffith, ML; Schlienger, ME; Harwell, LD; Oliver, MS; Baldwin, MD; Ensz, MT; Essien, M; Brooks, J; Robino, CV; Smugeresky, JE; Hofmeister, WH; Wert, MJ; Nelson, DV, “Understanding thermal behavior in the LENS process”, MATERIALS & DESIGN, 20 (2-3): 107-113 JUN 1999.