For absorbing media the concentration may be calculated directly from the optical transmission following the logarithmic dependence given in the Lambert-Beer law. Due to multiple scattering events in oil-water emulsions (e.g. milk, cream, etc.), these exhibit a nonlinear relationship between the attenuation and the oil concentration. We demonstrate that for increasing oil content in oil-water emulsions the attenuation first increases, then levels out, and finally even decreases for a fat content of 60%. Single-wavelength optical transmission measurements are found to be well suited for the in-line monitoring of oil-water emulsions of fat contents below 20%, e.g., for the in-line fat content monitoring of milk. Using experiments and ray-tracing simulations we evaluate system optimization.
Apertures are basic elements which can be found in many optical systems. Since optical systems are continuously being miniaturized and integrated, there is a need for small and inexpensive apertures to control beam shape and light intensity. Current aperture concepts for the micrometer regime rely on moving MEMS lamella or controlling fluids by capillary or electrostatic forces. We demonstrate an aperture concept for single-wavelength operation based on thermal tuning of a segmented thin film resonator. Thermal tuning changes the optical thickness of the elastomer cavity. This allows for adjusting the intensity to any level between constructive and destructive interference in a specific aperture segment. In order to demonstrate aperture operation we simulate thermal, mechanical and optical properties using finite element method and transfer-matrix method. We confirm our simulation results by experimental beam shape measurements and spatially-resolved spectral transmission and light intensity measurements.
The current autostereoscopic projection system is accomplished by array projectors. It is easy to realize optically but
has a drawback with size. Another type is to place the shutter on the screen. It saves the volume but reduces the
efficiency depending on how many views are produced. The shutter in the lens aperture has the same efficiency
problem, too. To overcome these problems, a full HD autostereoscopic projector based on the lens aperture switching
type is proposed. It has RGB laser sources and can produce 16-views or even higher stereoscopic images.
This system removes the shutter in the lens aperture by the opti-mechanism itself. The specific light on the lens
aperture coming from the point on the DMD is reflected to different angles. The proper angle of light is generated in
the object side by the relay and folding system. The UHP lamps or the LED rays are difficult to constrain in a relative
small cone angle. For this reason, the laser is applied to the design. The very small etendue of the laser is good for
this architecture. The rays are combined by dichroic filter from RGB laser sources then forming and expanding to the
mirror. The mirror is synchronized with DMD by the DSP control system. The images of different views are
generated by DMD and specific position of the mirror. By the double lenticular screen, the lens aperture is imaged to
the observer’s viewing zone and the 3D scene is created.
Virtually imaged phased arrays (VIPA) offer high dispersion compared to conventional gratings and have been proposed as buildings blocks for several photonic devices, including wavelength multipliers, chromatic dispersion compensators, waveformgenerators and pulse shapers. We introduce an elastomer-based tunable VIPA, providing an additional degree of freedom for these devices. In particular, we investigate its capability to implement reconfigurable optical interconnects. In a wavelength demultiplexing setup it allows for both compensation of misalignment as well as reconfiguration of a source wavelength to a target channel. It consists of an elastomer layer sandwiched between two structured silver coatings on a glass substrate forming the resonator cavity. Using Joule heating of the top silver layer a thermal expansion and a thermo-optic effect of the elastomer cavity is induced allowing for tuning the effective optical resonator cavity. We report a tuning span of one free angular range by a temperature increase of less than 10K induced by a power change in the low mW regime. Both resonance quality and tunability of the device are investigated.