QBC ParaLens: Technology

The QBC ParaLens is a unique microscope attachment that provides fluorescence microscope capability to virtually all standard compound light microscopes.  This is made possible through its innovative design, which combines the necessary components for fluorescence microscopy into a compact, durable configuration.

Epi-fluorescence microscopy, which means that excitation and emission light share the same pathway, is a standard in fluorescence microscope technology.  The ParaLens is built off of this technology, as depicted in the cutaway view shown to the top-right.  The ParaLens attaches to the light microscope through Royal Microscopy Society (RMS) threading (1), which is the standard for light microscopes.  Ring adapters are available through QBC Diagnostics for non-standard scopes.  Light enters the ParaLens (2) from a long life (20,000 hour) light emitting diode (LED) and is focused by a lens (3) through an excitation filter (4) and onto a dichroic mirror (5).  The excitation filter is designed to narrow the incident light bandwidth to be compatible with the biological application being investigated.  The light focused onto the dichroic mirror is reflected downward through the objective (6) to the specimen.  The specimen absorbs excitation light and subsequently fluoresces.  The objective captures and magnifies the fluorescence light, which is then transmitted through the dichroic mirror, which reflects wavelengths of higher energy than the fluorescent light.  The fluorescence light is further narrowed through the emission filter (7) and the optimized light is transmitted through the microscope to the viewer.

LED technology has revolutionized optical applications like fluorescence microscopy and is at the heart of the ParaLens technology.  LEDs provide a high intensity light source that can be chosen in broad and narrow bandwidths.  LEDs are fundamentally stable, durable, and long lived, which is due to several unique characteristics including, no heat generation in the LED, a compact format (relative to its vapor lamp counterparts), and non-filamentous based illumination.  The ParaLens light source also has low power requirements, so it can be powered by low voltage direct current sources such as a battery, solar pack, or laptop USB port.  This is especially useful for applications in low resource settings or labs that have an unstable local power supply.

Currently, the ParaLens is available in a blue light excitation configuration.  The graph below details the LED source, excitation filter, dichroic mirror, and emission filter specifications.  The LED source is a blue LED that produces light in the range of 410 to 510 nm, which is narrowed to 480 nm by the excitation filter.  The dichroic mirror reflects light of wavelengths of 510 nm and smaller and selectively transmits light of greater wavelength.  The emission filter blocks out all radiation of wavelengths of 480 nm and smaller, such as blue light, and transmits green, yellow, orange, and red light to the observer.  Examples of biological stains and other molecules that work well with this configuration include Acridine Orange, Auramine O, FITC, and green fluorescence protein (GFP).

Altogether, the technological advantages of the ParaLens provide a practical and economical solution for fluorescence microscopy, bringing fluorescence based diagnostic and research capabilities to the world.