Abstract:Precise direct-write lithography of 3D waveguides or diffractive structures within the volume of a photosensitive material is hindered by the lack of metrology that can yield predictive models for the micron-scale refractive index profile in response to a range of exposure conditions. We apply the transport of intensity equation in conjunction with confocal reflection microscopy to capture the complete spatial frequency spectrum of isolated 10 μm-scale gradient-refractive index structures written by single-pho… Show more
“…The exposure time was varied for a constant intensity and the cure depth measured using a confocal reflection microscope for optical profilometry. [24]
Figure 3e shows the mean cure depth as function of incident exposure E 0 .…”
Section: Resultsmentioning
confidence: 99%
“…Seven samples were fabricated to investigate the effect of exposure conditions on cure depth by varying exposure times (4, 6, 12, 18, 24, 48, and 96 s) ( n
= 3/group). The samples were soaked in ethanol for 72 h. The Cure depth was measured through the use of a custom-built optical profilometer as described by Glugla et al [24] …”
Application of 3D printed structures via stereolithography (SLA) is limited by imprecise dimensional control and inferior mechanical properties. These challenges is attributed to poor understanding ofpolymerization behavior during the printing process and inadequate post-processing methods. The former via a modified version of Jacob’s working curve equation that incorporates the resin’s sub-linear response to irradiation intensity is addressed by the authors. This new model provides a more accurate approach to select 3D printing parameters given a desired z-resolution and conversion profile along the depth of the printed part. The authors use this improved model to motivate a novel material design that can be post-processed to be indistinguishable from the polymer at 100% conversion. This approach employs a dual initiating system in which photo-initiated printing is followed by a thermal post-cure to achieve uniform conversion. The authors show that this approach enables fast printing times (10 s per layer), exceptional horizontal resolution (1–10 microns), precise control over vertical resolution, and decreased surface corrugations on a 10’s of microns scale. The techniques described herein use an acrylate-based SLA resin, but the approach can be extended to other monomer systems to simultaneously achieve predictable properties and dimensions that are critical for application of additive manufacturing in load-bearing applications.
“…The exposure time was varied for a constant intensity and the cure depth measured using a confocal reflection microscope for optical profilometry. [24]
Figure 3e shows the mean cure depth as function of incident exposure E 0 .…”
Section: Resultsmentioning
confidence: 99%
“…Seven samples were fabricated to investigate the effect of exposure conditions on cure depth by varying exposure times (4, 6, 12, 18, 24, 48, and 96 s) ( n
= 3/group). The samples were soaked in ethanol for 72 h. The Cure depth was measured through the use of a custom-built optical profilometer as described by Glugla et al [24] …”
Application of 3D printed structures via stereolithography (SLA) is limited by imprecise dimensional control and inferior mechanical properties. These challenges is attributed to poor understanding ofpolymerization behavior during the printing process and inadequate post-processing methods. The former via a modified version of Jacob’s working curve equation that incorporates the resin’s sub-linear response to irradiation intensity is addressed by the authors. This new model provides a more accurate approach to select 3D printing parameters given a desired z-resolution and conversion profile along the depth of the printed part. The authors use this improved model to motivate a novel material design that can be post-processed to be indistinguishable from the polymer at 100% conversion. This approach employs a dual initiating system in which photo-initiated printing is followed by a thermal post-cure to achieve uniform conversion. The authors show that this approach enables fast printing times (10 s per layer), exceptional horizontal resolution (1–10 microns), precise control over vertical resolution, and decreased surface corrugations on a 10’s of microns scale. The techniques described herein use an acrylate-based SLA resin, but the approach can be extended to other monomer systems to simultaneously achieve predictable properties and dimensions that are critical for application of additive manufacturing in load-bearing applications.
“…[6][7][8][9][10][11] Thus far, the mainstream approaches for accurate nanofabrication with arbitrary shapes are photolithography and laser direct write lithography. [12][13][14][15][16][17][18][19][20][21][22] Photolithography can provide large scale patterning, and laser direct write lithography has shown its great potential in the fabrication of complex three-dimensional micro-nano structures. However, they suffer from limited pattern resolution by the intrinsic property of light diffraction.…”
Nanolithography techniques providing a good scalability and feature size controllability are of great importance for the fabrication of integrated circuits (IC), MEMS/NEMS, optical devices, nanophotonics, etc. Herein, a cost-effective, easy...
“…Although optical methods of refractometry are still the main way to measure the refractive index [1], other approaches have been developed to solve this problem [2][3][4][5][6][7][8]. Among them, the methods based on the application of the transport-of-intensity equation (TIE) deserve special attention [9][10][11]. The main idea of these methods lies in the connection of the refractive index with the phase of the light wave that has passed through the optical medium.…”
Section: Introductionmentioning
confidence: 99%
“…Later, Yazdani et al [10] investigated the use of TIE to determine the nonlinear refractive index n 2 of a material. Finally, in 2018, Glugla et al [11] used the TIE to estimate the refractive index in 3D lithography. Note that the disadvantages of the proposed approaches are either the complex optical systems or the presence of additional time-consuming mathematical calculations.…”
A development of a method for measuring the refractive index of optical media based on the transport-of-intensity equation (TIE) is proposed. The method requires only a complementary metal-oxide semiconductor (CMOS) camera, which registers intensity distributions in several planes. The obtained intensity distributions are used to solve the TIE, known as a non-interferometric and deterministic method of measuring the phase of a light wave. Simple physical relations connecting the phase of the light wave that has passed through an optical medium and its refractive index allows to determine the latter. The results of the experiment confirm the applicability of the proposed method to the problems of optical refractometry.
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