To meet today's demanding requirements for increased performance, reduced size, lower mass, and cost, simple lenses containing multiple aspheric surfaces are required. It is now common for the number of aspheric surfaces used in an infrared lens to exceed the actual number of lens elements. Multiple aspheric and diffractive surfaces provide additional degrees of freedom in the lens design. This is required to achieve increased levels of imaging performance demanded by reduced pitch detectors. Aspheric surfaces also enable a greater diversity of materials to be used such that athermal solutions can be realized without the need for additional lens elements. More recent advances in detector technology will demand multispectral operation, but the requirements for simple, inexpensive optics will remain. Innovative use of aspheric components can also create very simple multispectral optics to fulfil this emerging need. This paper will review the range of applications that can be satisfied using no more than two optical components, highlighting the specific benefits that aspheric and diffractive surfaces provide. Consideration will also be given to future developments where enhanced functionality can be achieved using computational imaging techniques. Examples will be given for several military applications including weapon sights, driver's vision enhancement and remote weapon stations.
To meet today's demanding requirements for increased performance, reduced size, lower mass and lower
cost, simple lenses containing multiple aspheric surfaces are required. It is now a common feature that the
number of non-spherical surfaces used in an infrared lens design exceeds the actual number of lens
Judicious use of single-aspheric, dual-aspheric and asphero-diffractive surfaces provide additional degrees of
freedom in the lens design. This is required not only to improve the imaging performance demanded by
increasingly reduced pitch detectors, but to do so with solutions that are shorter and lighter whilst also offering
excellent image uniformity with minimised stray light. Non-spherical surfaces also enable a greater diversity of
materials to be used such that athermal solutions can be realised without the need for additional lens
This paper will review the range of applications that can be satisfied using no more than two optical
components; examining the specific benefits that non-spherical surfaces can provide. Consideration will also
be given to future developments where enhanced functionality can be achieved by using computational
imaging techniques. Examples will be given for optical designs that are suitable for numerous military
applications including weapon sights, driver's vision enhancement and remote weapon stations.
Thales Optics Ltd. have been involved in a joint funded technology demonstrator program between UK MOD and Thales called Thermal Imager for Dismounted Infantry, run in conjunction with QinetiQ. The aim of this program was to evaluate and demonstrate a cost effective route to equipping the infantry soldier with a small, lightweight, rugged, short range, weapon mounted thermal imaging sight, intended for mass deployment. To address the requirements of this program, Thales Optics Ltd. performed a detailed trade-off analysis considering the effect of using alternative sensors, displays and optical configurations on the sight cost, mass, volume, power and performance. This effort was supported with equipment trials and user assessments. Based on this work, six technical demonstrator sights have been manufactured and delivered to UK MOD for evaluation on several programmes including the UK's FIST soldier modernisation program. Thales Optics has since progressed the TIDI concept further into two product streams, a family of weapon sights called VIPIR and a surveillance sight called VIPIR-S. This paper will summarise the work undertaken on the TIDI program and how this has been applied to the VIPIR and VIPIR-S family of products.
Thermal Imager for Dismounted Infantry (TIDI), is a UK MOD / Thales Optics Ltd. joint funded technology demonstrator programme and is part of the overall programme managed by QinetiQ. The aim of this programme is to evaluate and demonstrate a cost effective route to equipping the infantry soldier with a small, lightweight, rugged, short range, weapon mounted thermal imaging sight; intended for mass deployment. TIDI is an unusual programme in that the requirement was not rigidly defined in terms of a detailed specification. Instead, the requirement was expressed in terms of the question 'What weapon sight performance can be achieved for a volume production cost of 5000 Euro?' This requirement was subject to the constraints that the sight mass should be less than 500 g and the volume should be less than 500 ml.
To address the requirements of this programme, Thales Optics Ltd. have performed a detailed trade-off analysis considering alternative uncooled LWIR sensor formats and technologies. The effect of using alternative sensors on the sight cost, mass, volume, power and performance has been compared. A design study has been performed concentrating on simplification of the optics, mechanics and electronics to minimise the overall sight complexity. Based on this analysis, a demonstrator sight has been designed that is cost effective and suitable for volume manufacture, whilst still offering useful performance to the user. Six technical demonstrator units based on this design have been manufactured and evaluated.
This paper will give an overview of the work completed to date on the TIDI program, including a description of the demonstrator hardware and its performance.
This paper will describe and discuss the head up display analysis routines that are used in the Thales Optics optical design software and how these have been enhanced and supplemented to meet the requirements of modern avionics specifications. Specific examples will be given illustrating methods of presenting collimation errors, binocular disparity, field of view, pupil shape and aperture definition on specific surfaces. Some of the methods of presenting collimation errors lend themselves to differential analysis making them useful for considering manufacturing tolerances.
A biocular magnifier is an optic that is sufficiently large to be used by both eyes together, and which presents a magnified virtual image at a finite distance from an observer. The design of such an optic is one of the most difficult tasks in optical design due to the extreme optical parameters, the relatively high level of residual aberrations, and the interface between the image and two-eye vision. As such, biocular magnifiers of reasonable magnifying power (>x4.5) cannot easily be analysed in a meaningful way using conventional optical design software. A number of years ago, a unique computer program was written that enabled the analysis of biocular magnifiers in the way in which they were used, that is with the spatial image being viewed by two small mobile apertures of nominally fixed separation. Utilising the power of modern PC computers, this program has been extended considerably so that it provides detailed graphical analysis of the visual aberrations appropriate to an extreme optical system usable by both eyes together. The reasoning behind the software and examples of the graphical analysis of biocular designs is given in the paper.
A method for computing the polychromatic MTF of hybrid refractive - diffractive elements is described taking into consideration the effects of not only the primary diffraction order but also the effects of additional parasitic diffraction orders. The results of this approach are compared with the more conventional single order calculation and with actual measured performance.
For certain markets and applications the cost of infrared lenses are critical in order to achieve customer expectations. Two possible methods of realising this requirement are the use of moulded optics or the use of multiple kinoform optics with no refractive power. Examples of such lenses are given along with discussion of the merits and limitations that each approach entails.
This paper illustrates the impact of using hybrid elements in mechanically athermalized objective lenses designed for use with uncooled focal pane arrays in the 8-14 micrometers waveband. Hybrid and conventional refractive lens designs are compared in terms of primary chromatic aberrations, MTF performance, transmission, mass, and cost.