An Electro-Optical System and a Method of Designing the Same
AssigneeLeonardo UK Ltd
InventorMichael EDWARDS
Life of this patent
Estimating the term…
Abstract
Many electro-optical systems include an environmental window that shield the sensor and optical train from environmental conditions. Where the electro-optical system is mounted on a high speed platform it can be necessary to shape the window away from the ideal optical shape of a hemisphere to one that is more aerodynamic. The optical train can include corrector elements to correct aberrations resulting from the non-ideal shape of the window. The exterior surface is configured to a specific biconic equation and that specified biconic equation is used to define the surfaces of the corrector element(s) of the optical train. This provides a more uniform wavefront error and magnification across the field of regard.
Claims7
A method of configuring an electro-optical system, the electro-optical system including:
- a non-hemispherical, non-planar, environmental window;
- a transmissive optical corrector;
- an optical train;
- a sensor disposed to receive optical rays which pass through the window, optical corrector and optical train;
- and
- a steering means configured to steer a line of sight of the sensor about a field of regard;
- wherein the method comprises:
- designing and configuring a surface geometry of the environmental window and a surface geometry of the optical corrector using matched surface sagitta equations, wherein the surface sagitta equations each include:
- a) a base biconic equation:
- z
- =
- c
- x
-
- x
- 2
- +
- c
- y
-
- y
- 2
- 1
- +
- 1
- -
- (
- 1
- +
- k
- x
- )
-
- c
- x
- 2
-
- x
- 2
- -
- (
- 1
- +
- k
- y
- )
-
- c
- y
- 2
-
- y
- 2
- in which:
- Z is the Sagitta, whereby z=0 is located at an intersection of a surface and optical axis;
- c is curvature in x or y, where in x and y are orthogonal directions about the optical axis;
- k is conic constant in x or y;
- and cx=1/Rx cy=1/Ry R is radius of curvature in x or y;
- and
- b) optionally, one or more further terms that define aspheric and/or or free form deviations from the base biconic equation;
- to provide a substantially uniform wave front error and substantially uniform magnification across the field of regard;
- and
- wherein surface sagitta equations are considered matched when they have a same number and form of meaningful additional terms, and where an additional term is considered meaningful when it alters the sagitta of any point on a surface by more than 100 nm from the base biconic equation.
An electro-optical system comprising:
- a non-hemispherical, non-planar, environmental window;
- a transmissive optical corrector;
- an optical train;
- a sensor disposed to receive optical rays that have passed through the window, optical corrector and optical train;
- and
- a steering means configured to steer the line of sight of the sensor about the field of regard;
- wherein a surface geometry of the environmental window and a surface geometry of the optical corrector are defined by matched surface sagitta equations wherein the surface sagitta equations each include:
- a) a base biconic equation:
- z
- =
- c
- x
-
- x
- 2
- +
- c
- y
-
- y
- 2
- 1
- +
- 1
- -
- (
- 1
- +
- k
- x
- )
-
- c
- x
- 2
-
- x
- 2
- -
- (
- 1
- +
- k
- y
- )
-
- c
- y
- 2
-
- y
- 2
- in which:
- Z is the Sagitta, whereby z=0 is located at an intersection of a surface and optical axis;
- c is curvature in x or y, where in x and y are orthogonal directions about the optical axis;
- R is radius of curvature in x or y;
- k is conic constant in x or y, and
- b) optionally one or more further terms that define aspheric and/or or free form deviations from the base biconic equation;
- such as to achieve a substantially uniform wave front error and substantially uniform magnification across the field of regard, and
- wherein surface sagitta equations are considered matched when they have a same number and form of meaningful additional terms, and where an additional term is considered meaningful when it alters the sagitta of any point on a surface by more than 100 nm from the base biconic equation.
Dependencies are inferred from the claim text.