Peter P. Clark

Athermalization of a single-component lens with diffractive optics

We describe a design method to athermalize a single-material lens element by using a kinoform on one surface to keep its focal length and aberrations constant with temperature. We diamond turned and thermally tested a plastic athermat and compared it to an uncompensated conventional lens.

Design of achromatized hybrid diffractive lens systems

The design of two broadband hybrid diffrve-refrve optical systems a landscape type lens and a Schmidt telescope was investigated. The systems were achromatized using the large negative dispersion characteristic of kinoforms. In the scalar wave regime these strucwres can approach 100 efficiency for one object point and wavelength but efficiency inevitably decreases when these parameters change. We evaluated polychromatic image quality taking diffraction efficiency into account by constructing properly weighted geometric point spread functions from several diffracted orders and calculating modulation transfer functions. The MTFs of the hybrid achmmats were improved at high spatial frequencies but reduced at low frequencies because inefficiency caused diffrtion into non-design ders. 2.

Modeling diffraction efficiency effects when designing hybrid diffractive lens systems.

We investigated the design of two broadband hybrid diffractive-refractive optical systems, a landscape lens, and a Schmidt telescope. The systems were achromatized by using the characteristically large negative dispersion of kinoforms. In the scalar wave regime kinoforms can approach 100% efficiency but only for one object point and wavelength. We evaluated polychromatic image quality, accounting for diffraction efficiency, by constructing weighted geometric point-spread functions from several diffracted orders and then calculating modulation transfer functions (MTFs). The MTFs of the hybrid achromats were improved at high spatial frequencies but were reduced at low frequencies because of diffraction into nondesign orders.

Compact finger imager

We present the design of a compact, low-cost finger imager, to be used for enrolling and recognizing individuals based upon their finger ridge patterns. The optical system employs viewing beyond the critical angle and darkfield illumination for maximum image contrast. The optical system is afocal and telecentric, achieving corrected distortion with oblique viewing.

Software for Optical Design: Has It Changed the Role of the Lens Designer?

Optical design software has become more powerful, easier to use, and less expensive than ever before. After describing the basic components of a traditional lens design program, the authors explore other tools that help to create better optical products.

Production application of injection-molded diffractive elements

We demonstrate that transmission kinoforms for visible light applications can be injection molded in acrylic in production volumes. A camera is described that employs molded Fresnel lenses to change the convergence of a projection ranging system. Kinoform surfaces are used in the projection system to achromatize the Fresnel lenses.