Wide field four mirror telescope using off-axis aspherical mirrors

508 - Abstract:
The European Space Agency (ESA) is interested in licensing a novel design for an ultra-wide field of view telescope. These types of devices are capable of imaging fields of view of over 6ox6o, being usually used in the visible and infrared spectral domain for earth and planetary observation and the detection of fast moving faint objects. This invention provides such a device, with high imaging performance and a flat focal plane, surpassing prior art offerings. License agreement is sought.


Ever since the invention of the telescope in the beginning of the 17th century in the Netherlands, this tool used to gaze into the night sky to study stars and other celestial objects has evolved from its humble origins as a couple of lenses held in place by a thin long tube. Reflective designs that used mirrors as the objective were made popular by Newton, as this configuration solved many optical and mechanical problems that plagued lenses based designs.

Modern pure reflective systems still face some hurdles, even after all the refinements made possible through centuries of development. One of these is the ability to achieve good image quality over a wide field of view. When considering the constraints for space based telescopes, namely the restriction in weight and size, the requirement for superior images is even more demanding.

A single mirror surface, even when considered fabrication error free, is incapable of perfectly imaging extended objects, under practical conditions. When a wide field of view is needed, those requirements are greatly increased. As such, by building a system with more surfaces, more degrees of freedom are introduced into the device, as accurately defining the properties of each mirror generates the design margin necessary to produce a superior system with great image quality. Also by using more complex mirror surfaces, such in aspheric designs, it is possible to better suit the system to our needs, albeit at an increased manufacturing complexity.

Prior art has provided us with telescopes featuring either aspherical mirror surfaces to reduce aberrations or a high number of surfaces to increase the degrees of design freedom. However no invention has used both technological advances together in a wide field of view device. The present invention devises such telescope, a four aspherical mirror device, capable of imaging with high performance an ultra-wide field of view. This device has minimal distortion in all the field of view and provides a flat image focal plane, an important feature to prevent the optical aberration called petzval field curvature.

Innovations and advantages

The successful application of groundbreaking technologies in the novel setting of ultra wide field imaging allowed the inventor to come up with a device that surpasses prior art offerings.

This was also designed with space applications in mind, which means it provides savings in space and weight when compared to similar offers.

Domains of application

The wide field four mirror telescope is well suited for super or hyoerspectral imaging missions and Earth observation missions with a very large swath.

It is also quite suited as a front telescope of a spectrometer with either a very large slit or multi slit configuration.

Last update: 6 March 2013

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