Seoul Semiconductor’s patented nPola
technology increases brightness levels 5 times
over existing LEDs. This technology took more
than 10 years to develop and is set to
revolutionise the LED lighting industry. nPola
stands for Numerous polarities and is related to
the substrate in which the LED is grown. nPola is
grown on a GaN (Gallium nitride) substrate,
whereas conventional LEDs use Sapphire or
Silicone substrate in which most of the energy is
converted to heat instead of light due to a defect
caused by lattice mismatch. nPola, however, does
not have the lattice mismatch issue like
conventional LEDs because the GaN epitaxy has
the same crystalline structure as the GaN growth
substrate. Furthermore, nPola technology
involves the utilization of the one of the nPola
non-polar planes in the GaN crystal, either the
a-plane or m-plane, whereas traditional LEDs
currently utilize the polar c-plane GaN epitaxy on
Sapphire or Silicon. nPola LEDs offer reduced
electrical resistance, increased electrical
efficiency, reduction in colour shift with varying
operating current and smaller device size.
With nPola, Seoul Semiconductor has already
improved the lumen density of LEDs by 5 times
over the conventional LEDs based on equivalent
die surface area and it expects to further improve
this margin to 10 times in future.
PDF accessibility requirements stipulate that word breaks must be represented explicitly in the PDF. However, TeX engines do not use space characters to separate words: they use interword glue. This project shows how you can use LuaTeX to replace interword glue with space characters and kerns without affecting the visual appearance of typeset text.
To understand the difference this makes for users of accessibility software, listen to this sound recording made using Adobe Reader DC's Read Out Loud feature. It records the two lines of text in this project being read out loud, before and after converting glue to spaces.
This is a plain TeX file compiled using LuaTeX. It is for experimental use only and not intended to be a full, production-quality solution. Primarily, it is designed to assist with understanding technical issues related to accessible PDFs. The Lua code in this project is based on the earlier Overleaf article Boxes and Glue: A Brief, but Visual, Introduction Using LuaTeX.
This project uses its own simple and very minimal OpenType font loader derived from this code: http://wiki.luatex.org/index.php/Use_a_TrueType_font.