The figure depicts the optical layout and meridional-plane ray-trace diagram of a four-element superachromatic near-infrared (IR) lens system. The system features a 30-mm-diameter entrance pupil, a focal-length-to-diameter ratio (ƒ/ number) of 4, and a field of view with a half-cone-angle width of 0.25°.
This optical design incorporates three key features:
- Spectral bandwidth greater than one octave in the near IR.
- Exceptionally low design geometric and chromatic aberrations. [Design root-mean-square (rms) geometric spot diameter <1 µm.]
- Commercial-level optomechanical tolerances for diffraction-limited performance.
This system was designed to replace a prior lens system that could not satisfy the applicable performance requirements because its tolerances were too tight. This system offers diffraction-limited performance over the wavelength band from 0.8 to 1.7 µm, even when the component lenses are fabricated and assembled with commercial-level optomechanical tolerances.
This work was done by Hiroshi Kadogawa of Caltech for NASA's Jet Propulsion Laboratory.
NPO-21078
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Commercial-Tolerance Superachromatic Near-IR Lens Systems
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Overview
The document presents a technical overview of a "Commercial-Tolerance Superachromatic Near-IR Lens System" developed by Hiroshi Kadogawa at NASA's Jet Propulsion Laboratory (JPL). This innovative optical design is engineered to operate effectively in the near-infrared (IR) spectrum, specifically within the wavelength range of 0.8 to 1.7 micrometers.
Key features of the lens system include a spectral bandwidth greater than one octave, exceptionally low geometric and chromatic aberrations, and the ability to maintain diffraction-limited performance even when manufactured with commercial-level optomechanical tolerances. The design achieves a root-mean-square (rms) geometric spot diameter of less than 1 micrometer, indicating high precision in optical performance.
The lens system consists of four elements and is characterized by a 30-mm-diameter entrance pupil, a focal-length-to-diameter ratio (f-number) of 4, and a field of view with a half-cone-angle width of 0.25 degrees. These specifications make it suitable for various applications requiring high-quality imaging in the near-IR range.
The development of this lens system was motivated by the limitations of a previous lens design that failed to meet performance requirements due to overly tight tolerances. The new design successfully relaxes these tolerances while still achieving the desired optical performance, making it more practical for commercial applications.
The document also includes technical details such as the radii of curvature for each lens surface and the axial distances between the lens surfaces, providing insight into the precise engineering involved in the lens design. The materials used in the lens construction include sapphire and optical glass (Schott SF6 or equivalent), as well as calcium fluoride (CaF2), which are selected for their optical properties in the near-IR spectrum.
Overall, this lens system represents a significant advancement in optical technology, combining high performance with practical manufacturing tolerances, and is poised to enhance various scientific and commercial applications in the field of optics. The work is part of ongoing research and development efforts at JPL, under the auspices of NASA, to push the boundaries of optical systems for space and terrestrial applications.
