About This Blog
This blog documents the engineering evolution of the Rejuvulite device over time. The most recent post titled Current Hardware reflects the current generation. Older posts document earlier iterations and are retained for transparency.

Written for a general audience; published in Innovating Resourcefully on Medium

 

Hardware Rev 2 in Fabrication — PCB Updates and App Progress

Rev 2 hardware is in fabrication. Here’s where things stand. Background The Rejuv is a handheld red and near-infrared light therapy device designed around a specific principle: that delivered dose — measured in J/cm² at the treatment surface — should be [...]

From Instrument to Plot: Measuring LED Output Under Real Constraints

1. Why measurement matters When evaluating a photonic device, the quantity of interest is the optical power delivered per unit area. As the LEDs are spread out, so too is the energy. Because the LEDs are distributed across a surface, the [...]

Power, Area, and Context: Why Total Watts Alone Are a Misleading Metric

A common criticism of compact, battery-powered devices is that they do not deliver sufficient total optical power (“watt”), particularly when compared to large, AC-powered panels. What determines local irradiance, however, is power density (mW/cm²) rather than total emitted power. For a [...]

Current Hardware

This post documents the optical and thermal behavior of the current generation device. Older blog posts document earlier design iterations and are retained for historical context. Purpose This post summarizes optical output and thermal behavior measurements for the current generation of [...]

Design Tradeoffs in a Handheld, Battery-Powered Optical Device

Simple Devices aren’t Simple At first glance, a handheld light-emitting device appears straightforward: an array of LEDs, a battery, and a housing. In practice, aligning such a device with the optical power densities commonly referenced in published light therapy research presents [...]