LEDs for repeatable transmitted illumination
Being solid-state, LED illumination systems offer instant on/off and irradiance control in 1% steps, allowing the user to easily optimise sample exposure. This is one of the key advantages when comparing LEDs with the traditional 100 W halogen lamp.
Another key difference between LEDs and halogen is that colour temperature remains constant as LED irradiance is increased or decreased, which makes colour balancing unnecessary and improves standardisation between sessions. Samples will appear identical even though irradiance could be up to five times greater. This is particularly beneficial for pathology applications, allowing samples to be compared even under varying light exposures. Moreover, LEDs are renowned for their long life and stability over time.

Colour temperature remains stable with the CoolLED pT-100WHT Transmitted Illumination System which offers a broad white 100 W halogen replacement.
Safe and comfortable transmitted illumination
Halogen lighting emits wavelengths in the UV, where modern LED illumination systems such as the pT-100-WHT are designed to reduce unwanted light in the UV which makes it safer and more comfortable, as risk of eye damage is significantly lower.

“Set up was very easy and the pT-100 Light Source was simple to operate. LEDs gave nice even illumination at 2% power. Higher powers were not necessary due to the brightness of the LED: 2% power with 5 msec or 10 msec exposure. There were no obvious signs of cell stress due to light toxicity over the duration of the 60min or 180min experiments I ran. Overall they are neat, simple to use and very efficient.” Tim Self, Head of School of Life Sciences imaging (SLIM), University of Nottingham, UK
Eliminating noise with narrow bandwidth transmitted illumination
Unlike halogen lamps, LED illumination systems enable the optimisation of image quality through the use of narrower spectrum wavelengths, and three narrow-bandwidth CoolLED pT-100 Transmitted Illumination Systems are available.

White light LED systems using a phosphored LED can be a source of background noise when used as a transmitted illumination system, which reduces image contrast. Narrow bandwidth illumination systems remove this background source to improve image quality and enhance analysis – even in thicker samples and applications requiring infrared light.
Higher contrast images: pT-100-525
Narrow bandwidth at 525 nm is optimised for the spectral response of most scientific cameras and reduces background noise from a phosphored LED.
Revealing details in thick samples: pT-100-635
Narrow bandwidth at 635 nm provides deeper penetration, which is excellent for revealing detail in thicker samples.
Infrared illumination of thicker samples: pT-100-770
Narrow bandwidth at 770 nm provides deeper sample penetration techniques that require the use of infrared light.
Enhancing electrophysiology with remote light delivery
Directly coupling the light source to the microscope is the norm when it comes to transmitted illumination. But for visualising samples during sensitive electrophysiology experiments, this can cause added electrical interference and impair data quality.
To help get the most accurate electrophysiology data possible, CoolLED provides a selection of LED Illumination Systems with remote light delivery using a liquid light guide. This allows positioning outside the faraday cage, removing any possible noise (e.g. electrical interference) resulting from the Illumination System. In addition to standard direct fit models, liquid light guide variants are available for:
pT-100-WHT – A broad white light Illumination System and true 100 W halogen replacement.
pT-100-770 – Narrow bandwidth Illumination System at 770 nm for deeper light penetration and ideal for visualising thick tissue slices.
Interested? Try it out!
If you’re not sure whether an LED Illumination System is right for you, we can provide a free loan unit for testing, with no obligation to purchase. Please contact us at info@coolled.com for more information.