LLNL pioneered the use of tomographic reconstruction to determine the power density of electron beams using profiles of the beam taken at a number of angles. LLNL’s earlier diagnostic consisted of a fixed number of radially oriented sensor slits and required the beam to be circled over them at a fixed known diameter to collect data. The new sensor design incorporates annular slits instead, and it removes limitations on the number of angles at which electron beam profiles can be taken. The new annular slit scanning method can profile a beam while only needing a span of only 180 deg. to acquire a full spectrum of data; this enables the sensor surface to be fabricated from a monolithic piece of refractory metal, which improves dimensional accuracy. The radial nature of the scan…

LLNL has developed a system and method that accomplishes volumetric fabrication by applying computed tomography (CT) techniques in reverse, fabricating structures by exposing a photopolymer resin volume from multiple angles, updating the light field at each angle. The necessary light fields are spatially and/or temporally multiplexed, such that their summed energy dose in a target resin volume crosslinks the resin into a user-defined geometry. These light-fields may be static or dynamic and may be generated by a spatial light modulator (SLM) that controls either the phase or the amplitude of a light field (or both) to provide the necessary intensity distribution.

LLNL researchers have designed and tested performance characteristics for a multichannel pyrometer that works in the NIR from 1200 to 2000 nm. A single datapoint without averaging can be acquired in 14 microseconds (sampling rate of 70,000/s). In conjunction with a diamond anvil cell, the system still works down to about 830K.

LLNL has developed an optically clear iodine-doped resist that increases the mean atomic number of the part. AM parts fabricated with this resist appear radio-opaque due to an increase in the X-ray attenuation by a factor of 10 to 20 times. Optical clarity is required so that the photons can penetrate the liquid to initiate polymerization and radio opacity is required to enable 3D computed tomographic imaging for final inspection via X-rays. The refractive index of these resists is matched to that of the immersion medium of oil-immersion objective lenses. As a result, these resists may also be used with high numerical aperture immersion objectives during dip-in two-photon lithography – a submicron additive manufacturing technique for printing tall millimeter-scale structures.

The LLNL method for optimizing as built optical designs uses insights from perturbed optical system theory and reformulates perturbation of optical performance in terms of double Zernikes, which can be calculated analytically rather than by tracing thousands of rays. A new theory of compensation is enabled by the use of double Zernikes which allows the performance degradation of a perturbed and compensated optical system to be calculated with a matrix multiplication using paraxial quantities rather than by iteration involving tracing large sets of rays. Almost no additional ray-tracing beyond that used in nominal design is required.

LLNL has solved the challenges of depth-resolved parallel TPL by using a temporal focusing technique in addition to the spatial focusing technique used in serial writing systems. We temporally focus the beam (through optical set-up design) so that a sharp Z-plane can be resolved while projecting 2D “light sheets” that cause localized photo-polymerization. This enables printing of complex 3D structures in a parallel fashion. To minimize the errors arising from discretization of 3D structures, LLNL has also developed techniques to “bend” the 2D light sheet into a 3D surface for printing of curved features.

The inventive elements of the LLNL apparatus are the arrangement of the laser light, the digital mask, and the axis of the collimating optics and the relative size of the…

By combining 3D printing and dealloying., researchers at LLNL have developed a method for fabricating metal foams with engineered hierarchical architectures consisting of pores at least 3 distinct length scales. LLNL’s method uses direct ink writing (DIW), a 3D printing technique for additive manufacturing to fabricate hierarchical nanoporous metal foams with deterministically controlled 3D multiscale porosities. Arbitrary shapes can be printed according to the application requirements. Moreover, the structure of three levels of porosity can be tuned independently which enables application specific multiscale architectures. In this method, DIW is used to extrude a gelbased metals mixture from a small nozzle into 3D periodic porous structures. The "ink" materials used for DIW are…

LLNL scientists have developed a new metal additive manufacturing technique that uses diode lasers in conjunction with a programmable mask to generate 2D patterns of energy at the powder surface. The method can produce entire layers in a single laser shot, rather than producing layers spot by spot as is currently done in powder bed fusion methods.