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The Value of Condenser Lenses in Projection Systems

28th May 2019

Condenser lenses play a valuable role in the function of a range of imaging devices and this includes slide projectors. In this post we are going to take a closer look at how condenser lenses work, together with the value they bring to all types of projection applications.

What is a condenser lens?

A condenser lens is made up of a pair of matched convex lenses. These are placed back to back so that the curved surfaces face each other in the centre, with the flat surfaces sitting on the outside.

The advantage of this system is that it provides a simple method of correcting aberration which can be common with traditional lens types. Reduced aberration means the quality of the projected image will be much improved.

How does a condenser lens work?

The condenser lens collects light from sources which would usually be divergent. It redirects and condenses the light beam so that it floods the projector’s lens system.

The first lens of the pair will usually collect the divergent light emanating from the illuminator, whilst the second lens outputs the light as a convergent cone.

Without a condenser lens, a projected image is likely to be dim and / or of low intensity, making it difficult to view.

What are the advantages of using a condenser lens in projector systems?

The aim of the condenser lens in a projector system is to align the light rays into a straight path. This allows the maximum amount of light possible to reach the projector screen. A high quality condenser lens will allow the aperture of the projector lens to be reduced in size. This results in a sharper image, together with valuable cost savings, so benefits all round.

In short, the better the quality of the condenser lens, the greater the output quality and efficiency, and the lower the overall cost of the projector.

What are the benefits of using aspheric condenser lenses?

Plano-convex (PCX) condenser lenses are moulded on both surfaces, whilst aspheric condenser lenses are moulded on the aspheric surface and then polished and ground on the opposite face, a process which enhances the precision of the lenses.

Aspheric lenses have the ability to condense light at a short focal length which is superior to that which can be achieved with spherical lenses.

Aspheric lenses are known to deliver superior performance due to their more complex surface profile which is known to further reduce spherical aberration, whilst plano-convex condenser lenses are often the choice where budget is an important deciding factor.

Coatings and toughening for thermal protection

All condenser lens types can be engineered to meet exacting specifications. The lenses are hardened to increase their robustness so that they are less affected by extreme temperatures and damage.

Antireflective lens coatings further enhance the quality of the projected image by eliminating stray light.

Condenser lenses from a globally renowned optics specialist

At Knight Optical we have been working alongside a host of optical system manufacturers in the entertainment and leisure industry for several decades, ensuring that the applications they are developing are given the best possible competitive edge courtesy of precision grade optical components.

Customisation of optical components is our speciality. We appreciate the importance to designers of being able to engineer their applications as flexibly as they can. We regularly supply condenser lenses edged to smaller diameters to suit compact style projectors and are able to re-shape standard circular lenses to square or rectangular apertures.

Our condenser lenses are usually crafted from borosilicate glass or equivalent but increasingly, due to high demand, we are making them using fused silica, a high performance material that is known to deliver on robustness, range of transmission and thermal stability.

When it comes to quality, customers can rely on precision accuracy by way of our state-of-the-art metrology laboratory stocked with the very best optical testing and measurement instruments and managed by some of the most respected experts in the industry.

If you are currently developing a new projector system, or seeking to upgrade an existing model by making use of the latest prevailing optical technology, we have the expertise to assist you. Contact us today. Just ask to speak to our multilingual technical sales team and we’ll be pleased to provide all the advice you need.

For more information on our range of condenser lenses visit