Posts Tagged ‘commercial lenses’
When is a Fresnel Lens not a Fresnel Lens?
It’s well known, to those who know it well, that diffractive optics and refractive optics suffer chromatic shift but that is opposite in sense. This is illustrated nicely by comparing a blazed grating with a Fresnel lens as shown below. Bear in mind these figures have more artistic license than a Pink Floyd album cover! …
Read MoreEtendue of a Fly’s Eye Illuminator
In the first blog article I introduced the subject of étendue and its importance in illumination systems. The example used was simple optical relay, but many systems utilize fly’s eye arrays to provide homogenous illumination. What is the impact of splitting a beam into smaller beamlets on the étendue? Consider this system….. On the left…
Read MoreWhether it’s hot or cold, stay focused! What’s involved in lens athermalization.
A huge range of commercial-off-the-shelf lenses are readily available from many catalog optics suppliers. However, sometimes what you want is not available and you just need a custom design. One of the features often required in custom lenses is that they operate over a wide temperature range without manual or motorized adjustment. You find such…
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