Many applications, both in commercial and defense industries, require uniform diffusion at either a broad
wavelength range, or at multiple discrete wavelengths. Currently employed technologies have trade-off's
between their ability to control the angular distribution and uniformity of the output beams intensity profile,
and the ability to suppress 0th order for the devices in a way that can be volume manufactured to tolerate
environmental extremes. At Tessera, we have developed a binary lithography technique which nearly
eliminates the 0th order over a much broadened wavelength range, while maintaining much greater control
over the angular distribution of the beam. In this paper we describe technology and how it has been applied to
the design and manufacture of a top-hat diffuser profile for the wavelengths of 3.95μm and 4.6μm. The
procedures used for testing, as well as the test results, are provided courtesy of Aculight Corporation.
Laser based illumination has proven to be useful in a number of defense and security applications such as target
illumination, counter measures, mine detection, and LADAR. For some of these applications, it is desirable to create an
illumination with a specified angular dependence, while for others it is desirable to have a particular illumination profile
at a specified plane. Conventional approaches to these requirements often involve beam truncation or beam energy
redistribution with the target plane having a limited range. Diffractive optic based approaches are capable of providing
high performance solutions to many of these problems. For example, a diffractive diffuser approach can be used to
create tailored intensity profiles which can be much more efficient than using a truncated Gaussian beam in the region
of interest. In particular, the binary optics approach to fabrication of diffractive optics provides a repeatable, high
quality method for volume manufacturing of these elements.
At Digital Optics Corporation, we have designed and fabricated wafer-based optics for a variety of applications in the
157nm-14μm wavelength range. During this talk we will present design and experimental results for several
applications illustrating the use of diffractive elements for laser based illumination.
In the low-to-mid IR wavelength range there is a need for high performance, cost effective aspheric optics. Silicon has many advantages including high transmission and a high refractive index, but it can be very difficult to diamond turn. The resulting fabrication errors reduce efficiency and increase scattering and stray light. Wafer-based lithographic techniques can be used to make diffractive and refractive elements in both silicon and germanium. Advantages of diffractive structures such as: thinner elements, highly aspheric and even non-rotationally symmetric phase functions and chromatic compensation make this an attractive technology compared to diamond turning. In addition, wafer based fabrication makes these elements cost-effective in many applications. At Digital Optics Corporation, we have designed and fabricated wafer-based optics for use in the 1.3-14 micron range. In this paper, we will discuss the design, fabrication and evaluation of several product categories including a diffractive germanium beamshaper, a diffractive silicon aspheric lens, and a diffractive silicon spiral lens.