Polymerase Chain Reaction, referred to as PCR, is a laboratory technique used to amplify DNA and RNA sequences. The repeated raising and lowering of the temperature of the sample enables the sequence to be copied billions of times. This is one of the most important techniques used in bioscience, diagnostics and forensic science for typing and quantifying different microbial agents. In recent months, RT-PCR has played a critical role in the fight against COVID 19 by detecting and identifying the presence of specific genetic material in any pathogen, including a virus.
In Real Time PCR, a light source, often a halogen lamp, is used to excite targeted genetic materials marked with fluorescencent dyes. In the case of the PCR diagram shown below, the light is shown through a number of different excitation filters. A camera records the fluorescence from behind the emission filters.
Halogen lamps are known for stable spectral output, moderately high efficiency, and significant rated life, making them a common light source for PCR machines.
Features of a halogen lamp
Broad spectral bandwidth – Halogen lamps are available in a variety of color temperatures that emit a broad spectral bandwidth from near UV to far infrared. This broad band expands the capability of the PCR machine. Other sources such as lasers and LEDs have a very narrow bandwidth. Systems employing LED light sources have more limited capabilities because it requires many different LEDs at different bandwidths.
Low cost – Halogen lamps carry a lower cost to equivalent Laser sources.
Dispersion - Halogen lamps are available with numerous types of filaments (C-6, C-8, CC-6, CC-8, C-Bar-6) and a variety of reflectors, (dichroic, parabolic, ellipsoidal, flood, narrow beam, faceted, specular and metal (Silver, Aluminum and Gold) coated to offer more precise control of the excitation wavelengths, uniformity, focus and size of the coverage of the target area for each specific use case.
Below is an example of a C-8, and C-6 filaments in an MR16 specular (smooth) and facetted reflector all taken at the same measurement distance:
(Click to see larger image)
ILT manufactures lamps suitable for PCR applications. You can view all of our halogen lamps here. ILT also offers customization and precision designs to assure the correct wavelengths of light reach and fully illuminate the sample. If you have a PCR application requiring a lamp or lamp reflector assembly, and would like to speak with one of our specialists, please fill out our contact form and one of our representatives will be in touch.