An approach to designing multiconfiguration afocal telescopes is developed and demonstrated. Freeform surfaces are used to maximize the achievable diffraction-limited zoom ratio while staying in a compact volume for a two-position multiconfiguration afocal optical system. The limitations of these systems with three-mirror beam paths are discussed and subsequently overcome by introducing an additional degree of freedom. In a four-mirror beam path system, the goal of a 5x zoom ratio is achieved with a compensated exit pupil and diffraction-limited performance. A significant benefit in optical performance when using freeform surfaces is shown compared to more conventional surface types.
Exit pupil quality analysis and optimization in freeform afocal telescope systems
Afocal telescopes are often used as foreoptics to existing imaging systems to allow for application flexibility. To properly combine an afocal telescope with an existing imaging system, the exit pupil of the afocal telescope and the entrance pupil of the imaging system must be coincident. Additionally, the exit pupil of the afocal telescope must be well-formed; that is, it must be the correct size and shape to mitigate pupil-matching challenges. This work introduces processes for designing freeform afocal telescopes with an emphasis on understanding how to analyze and control the exit pupil quality of such systems. The included 3-mirror design examples demonstrate the advantages of using freeform surfaces in afocal systems and quantify the tradeoffs required to improve the exit pupil quality.
more » « less- PAR ID:
- 10430971
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 31
- Issue:
- 15
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 24691
- Size(s):
- Article No. 24691
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
Aikens, David M ; Rehn, Henning ; Thibault, Simon ; Uhlendorf, Kristina (Ed.)Afocal telescopes are often used as foreoptics to existing imaging systems. Here, we discuss some unique aspects of designing afocal systems and detail various afocal design studies we performed using freeform optics.more » « less
-
Aikens, David M ; Rehn, Henning ; Thibault, Simon ; Uhlendorf, Kristina (Ed.)We consider the requirements for first-order pupil location control using the matrix method for both finite-conjugate systems and afocal systems at infinite imaging conjugates. We show that two-element systems allow for only limited pupil location control, while with three elements or more the first-order pupil locations can be freely and independently controlled.more » « less
-
more » « less
Point spread function engineering uses specially designed phase plates placed at the exit pupil of an imaging system to reduce defocusing sensitivity. A custom phase plate is typically required for each system to enable extended depth of field imaging, so methods enabling variable extended depth of field imaging are of particular interest. In this paper, we discuss the fabrication of previously designed fixed cubic phase plates and variable phase plate pairs with quartic surface profiles and present a novel application of a point source microscope for performance characterization. Experimental measurements of through-focus point spread functions are compared with predictions to demonstrate and characterize the extended depth of field for both fixed and variable freeform phase plates.
-
Driven by the development of freeform imaging systems, we have combined several concepts and techniques from the literature to analytically generate unobscured freeform starting point designs that are corrected through the third-order image degrading aberrations. The surfaces used in these starting point designs are described as a base off-axis conic that images stigmatically for the central field point, also known as a Cartesian reflector, with an aspheric departure “cap” (quartic with the aperture) added to the base off-axis conic to correct for the third-order image degrading aberrations. Once the aspheric caps are added to the surfaces, the system is then optimized using higher order freeform terms while leaving second-order terms frozen to preserve the focal length of the system during optimization. This technique is used to survey the three-mirror freeform imager solution space. Several systems that are the result of this technique are shown, with different numbers of internal images, internal pupil conjugates and folding geometries.more » « less
