HOLOEYE offers customized design of diffractive optical elements. Among the computational design methods used are Iterative Fourier Transform Algorithms (IFTA), direct binary search (DBS) algorithms, gradient search algorithms and methods based on the determination of geometrical map transformations. We have capabilities for designing DOEs for projecting patterns on inclined surfaces and with arbitrary angles of diffraction. This allows us to precisely place diffraction spots freely on a surface of interest and to thereby exactly realize very complex patterns. The obtained element design will be tested in wave-optical simulation prior to fabrication.

Light Source:

• Type (cw laser, pulsed laser, LED, other)
• Wavelength (center and bandwidth)
• Power (average and/or peak)
• Beam profile (diameter, divergence, M² quality)

Optical Function:

• Desired light field distribution (shape, uniformity)
• Working distance / field of view
• Diffraction angles
• Inclination or shape of target surface

Application:

• Element material
• Element size and shape
• Sensor type (CCD/CMOS/human eye)
• Specific property requests

The design data is optimized for minimum fabrication error dependency and the data conversion for the fabrication facilities is monitored to ensure optimal properties of the master elements. The fabrication technology will be chosen to meet specifications on the one hand and to minimize cost on the other hand. For diffractive structures with pixel sizes down to 50nm, it is necessary to use e-beam direct writing lithography. In this technology, the high spatial resolution results in comparatively long writing times per area. For diffractive structures with more coarse structures (feature sizes >1µm) the necessary resolution can be reached with laser lithography and a shorter writing time.

After the sequential writing process, there are different technology options for creating surface relief structures. With etching techniques (e.g. reactive ion etching) it is possible to create a surface relief structure in the substrate material. With electroplating it is possible to generate tools for replication processes like injection moulding.

Replication technologies represent a major economic success factor in diffractive optics because replication significantly reduces the cost of each single optical element. The fabrication of a master component with an optical microstructure can be very cost-intensive. With a replication method the optical structure of a master component can be copied in high quantities onto different optical media, thus reducing the effective cost per element significantly. Using accordingly manufactured master structures, HOLOEYE can add value by its own replication methods to improve the performance of diffractive elements with respect to specific merit parameters.

HOLOEYE offers high-precision replication of small quantities for applications in technical optics at reasonable cost. Replication is possible in almost 50 different materials for:

• Different material requirements
• Varying wavelengths (for optimum diffraction efficiency)
• Index of refraction (for optimum diffraction efficiency)
• Replication on surfaces of different media
• Different environmental conditions (temperature, humidity)

HOLOEYE also offers high precision mass replication on glass substrates. The diffractive optical elements are delivered in customers’ requested shape and size or integrated with a customized mechanical holder.