Solid-state light engines illuminated
How solid-state light engines can meet the exact needs of many biotech and industrial applications
When the company launched its first illuminators in 2008, Lumencor’s use of the product name ‘Light Engine’ raised a few eyebrows and even received a few scowls, the company’s co-founders now laughingly recollect. You may also recognise the term light engine from the high-definition television market, from which it was borrowed.
Claudia Jaffe, co-founder and executive vice president at Lumencor, explained: ‘Our founder, with a deep technical background in solid-state physics and lighting for single-molecule detection as well as flat-panel displays, borrowed this term from the display industry. He applies it to the many lighting needs of life and material science applications, which we identified as sorely underserved by the LED products then on the market.’
LEDs, for example, are well known for the ‘green gap’, a window of around 500 to 600nm in which outputs are notoriously weak. To overcome this, Lumencor’s Light Engines incorporate proprietary light pipes, designed to boost the brightness in this green gap spectral region.
These light pipes are one of the numerous solid-state technologies used in the company’s Light Engines, which also include LEDs and diode lasers. By balancing the attributes of these solid-state technologies, light engines can provide the illumination required for a range of applications. Jaffe explained: ‘Today’s various solid-state light sources offer both advantages and disadvantages. It is only with a careful assessment of both their benefits and limitations that the best illumination solutions can be identified for the breadth of light-driven life and material science applications and engineered and integrated into a turn-key illumination box.’
For example, light engines are capable of achieving high optical powers. Jaffe explained: ‘In the life sciences, highest resolution and de-noising techniques with large imaging areas demand more and more optical power.’
Confocal microscopy, for example, delivers around three per cent of the optical source output to the sample plane. So, a high-upstream optical power is required to overcome the inherent photon attenuation of the technique.
When it comes to structured illumination and super-resolution microscopy, large fields of view are required and large format cameras demand high brightness and power. But these systems aren’t well served by simple LEDs or inexpensive lasers, which are neither stable nor robust.
‘Spatial and systems biology is becoming increasingly multiplexed and addressing larger sample sizes; it cannot be supported without both spectral breadth and purity of stable excitation light across the ultra-violet, visible and near-infrared,’ Jaffe explained.
There are also other attributes to consider. Live-cell imaging videos with multi-coloured proteins, for example, also require switching times of the order of tens of microseconds (or faster) between discrete, clean excitation bands. This is where the company’s Light Engines can help again, eliminating the slower mechanical filter motion in front of bulbs when filtering and blocking. So, switching times can decrease by several orders of magnitude.
Light engines also address some of the challenges faced when using off-the-shelf lamps that are not reliable enough for many clinical science applications, including diagnostics and treatment.
These illumination systems must be well-controlled and provide repeatable, precise optical power, according to Jaffe, who added: ‘To better serve optically-selective surgery, including robotic surgery, Lumencor builds both white light and near-infrared laser-containing Light Engines with power, colour temperature and colour rendering indexes to match xenon bulbs, the historical mainstay of that industry.’
Now, light engines can provide the high stability and reproducibility required for a range of biomedical applications, driving high content screening of drug targets, live-cell imaging, genomic analyses, diagnostics and treatment like endoscopy and robotic surgery.
‘We also have a long history of supporting numerous industrial metrology applications like semiconductor test and measurement equipment including bright and dark field microscopy, ellipsometry, and profilometry,’ Jaffe said.
In the wider industrial markets, test and measurement equipment for metrology applications was once only served by ‘hundreds of thousands and even milliondollar lighting subsystems,’ according to Jaffe. ‘They had to be maintained and demanded field service over time with costly replacement parts.’
Now, metrology is moving away from archaic bulbs for routine analyses and towards solid-state illumination, which provides both better stability and longevity in fabs demanding 24/7 operation to meet the growing demand.
As a result, these onceexpensive optical trains can now be supported by self-contained, turnkey light engines designed to provide either coherent or incoherent light for defect analyses and 3D packaging needs, according to Jaffe, who added: ‘Further, light engines have documented lifetimes of more than 10 years with no catastrophic failure modes – in stark contrast to lamp technologies (which need new bulbs annually and even biannually).
Solid-state technologies also eliminate the need for toxic mercury-containing lamps for test and measurement purposes, removing the need for expensive and dangerous mercury disposal.
In its latest white paper, Lumencor describes how its solid-state Light Engines allow for the customisation of specifications to meet application-specific lighting requirements.
‘Optimisation of the light source selection for light-driven biotech and industrial applications demands a thorough consideration of the spectral, spatial, and temporal requirements of the instrument, which the illuminator is intended to support. Off-the-shelf solutions for illumination are often too simplistic and frankly don’t meet the technical challenge,’ Jaffe explained.
‘Often one technology can satisfy some but not all the instrument requirements. An informed selection of a mix of technologies is often the best strategy,’ Jaffe added.
Yet, the industry was slow to accept light engines when this technology hit the market in 2008, according to Jaffe, who explained: ‘When Lumencor first started manufacturing, many people equated solid-state with LEDs and the limitations they represented in terms of power, brightness, and spectral breadth. It was a significant uphill climb to convince scientists and engineers who had tried LEDs and found them wanting to entertain using a light engine.’
Jaffe added: ‘Certainly, the purchase price may have discouraged first users from making the switch from archaic lamps to Light Engines. Yet today, any informed analysis of the cost of ownership including the complete elimination of service, maintenance, and replacement parts, shows that in as short a time as 2.5 years the purchase price is recuperated in cost savings over any lamp, while maintenance costs are eliminated entirely for the Light Engine lifetime.’ Jaffe concluded: ‘The use of solid-state light engines needs to become the rule, not the exception. That solid-state light engines are a smart and economical investment in clean illumination for biotech and industrial metrology must be the state-of-the-art expectation.’
Find out more about why optimising the light source selection for light-driven biotech and industrial applications demands a thorough consideration of the spectral, spatial, and temporal requirements of the instrument which the illuminator is intended to support, by downloading the latest white paper.