A head-up display device includes optical path deflecting means, a first mirror having power, a second mirror having power, and a light-blocking member that is provided with an aperture. Display light emitted from an image display surface is reflected by the optical path deflecting means, the first mirror, and the second mirror in this order, passes through the aperture, and reaches an image reflective surface. The image display surface and the optical path deflecting means are disposed on the same side as an observer and on a side opposite to the first mirror with respect to luminous flux that travels toward the aperture from the second mirror, and the image display surface is disposed on a side opposite to the second mirror with respect to luminous flux that travels toward the first mirror from the optical path deflecting means.

An off-axis hybrid surface three-mirror optical system comprises a primary mirror, a secondary mirror, a tertiary mirror, and an image sensor. A reflective surface of the primary mirror is a sixth-order polynomial freeform surface of xy. A reflective surface of the secondary mirror is a sixth-order polynomial aspheric surface of xy. A reflective surface of the a tertiary mirror is a spherical surface of xy.

The invention relates to an imaging system for imaging a surface on an astronomical body, such as the Earth. The imaging system such as a satellite imaging system comprises a telescope comprising at least first and second curved mirrors wherein the second mirror is located downstream of the first mirror, relative to a propagation direction of imaged light, a digital image sensor or a slit aperture arranged at the focal plane of the telescope, and an actuator system arranged for tilting the second mirror or other curved mirror located down-stream of the first curved mirror for scanning the line of sight of the imaging system in a scanning direction (221) on the surface within a field of view (231) of the imaging system.

A freeform surface off-axial three-mirror image-side telecentric optical system comprises a primary mirror, a secondary mirror, a tertiary mirror and an image sensor. The secondary mirror is the aperture stop. A reflective surface of the primary mirror is a fourth-order polynomial freeform surface of xy. Each of a reflective surface of the secondary mirror and a reflective surface of the tertiary mirror is a sixth-order polynomial freeform surface of xy.

A oblique camera lens includes: a primary mirror configured to reflect a light ray to form a first reflected light; a secondary mirror located on a first path of light reflected from the primary mirror and configured to reflect the first reflected light to form a second reflected light; a tertiary mirror located on a second path of light reflected from the secondary mirror and configured to reflect the second reflected light to form a third reflected light; and an image sensor located on a third path of light reflected from the tertiary mirror and configured to receive the third reflected light; wherein each of the first reflecting surface and the third reflecting surface is a sixth order xy polynomial freeform surface; and a field of view of oblique camera lens in an Y-axis direction is greater or equal to 35 and less than or equal to 65.

A method for designing a oblique camera lens comprising: step (S1), establishing an initial system, the initial system comprises a primary mirror initial structure, a secondary mirror initial structure, and a tertiary mirror initial structure; step (S2), building a new image relationship; step (S3), keeping the primary mirror initial structure and the secondary mirror initial structure unchanged; selecting a plurality of first feature rays; step (S4), keeping the secondary mirror initial structure and the tertiary mirror unchanged; selecting a plurality of fields and a plurality of second feature rays.

A three-aspherical-mirror anastigmat telescope comprises: means for moving the third mirror linearly along the optical axis of the telescope to make the focal length of the telescope change between a minimum focal length and a maximum focal length, a deformable and controllable mirror, means for changing the optical path between the deformable mirror and the detector, the third mirror having a new conicity determined from an initial conicity, the initial conicity determined from the Korsch equations, the new conicity determined so that the telescope has, in the absence of the deformable mirror and for the minimum and maximum focal lengths, aberrations that are compensable by the deformable mirror, the fixed median position of the deformable mirror and the form of its surface, for the minimum focal length and maximum focal length, respectively, being determined so as to correct the compensable aberrations and to optimize image quality in the focal plane of the telescope according to a preset criterion.

A three-aspherical-mirror anastigmat telescope comprises means for moving the third mirror linearly along the optical axis of the telescope so as to make the focal length of the telescope change to a plurality of focal lengths between at least a minimum focal length and a maximum focal length, a plurality of aspherical optical components respectively associated with the plurality of focal lengths, the third mirror having a new conicity determined from an initial conicity, the new conicity being determined so that the telescope has, in the absence of the aspherical components and for the minimum and maximum focal lengths, aberrations that are compensable by the aspherical components, the position and the form of the surface of each aspherical component being determined so as to correct the compensable aberrations of the telescope for the associated focal length and to optimize image quality in the first focal plane of the telescope according to a preset criterion.

An off-axis aspheric three-mirror optical system comprises a primary mirror, a secondary mirror, and a tertiary mirror. Relative to a first three-dimensional rectangular coordinates system in space, a second three-dimensional rectangular coordinates system is defined by a primary mirror location, a third three-dimensional rectangular coordinates system is defined by a secondary mirror location, and a fourth three-dimensional rectangular coordinates system is defined by a tertiary mirror location. The primary mirror in the second three-dimensional rectangular coordinates system, the secondary mirror in the third three-dimensional rectangular coordinates system, and the tertiary mirror in the fourth three-dimensional rectangular coordinates system are all sixth-order polynomial aspheric.

A method for designing an off-axis aspheric optical system comprises establishing an initial system and selecting a plurality of feature rays R.sub.i (i=1, 2 . . . K); solving a plurality of feature data points (P.sub.1, P.sub.2, . . . P.sub.m) to obtain an initial off-axis aspheric surface A.sub.m by surface fitting the plurality of feature data points (P.sub.1, P.sub.2, . . . P.sub.m), wherein m is less than K; introducing an intermediate point G.sub.m to solve a (m+1)th feature data point P.sub.m+1, and fitting a plurality of feature data points (P.sub.1, P.sub.2, . . . P.sub.m, P.sub.m+1) to obtain an off-axis aspheric surface A.sub.m+1; repeating such steps until a Kth feature data point P.sub.K is solved, and fitting a plurality of feature data points (P.sub.1, P.sub.2, . . . P.sub.K) to obtain an off-axis aspheric surface A.sub.K; and repeating above steps until all the aspheric surfaces of the off-axis aspheric optical system are obtained.