The paper describes the design of an inexpensive holographic optical tweezers setup. The setup is accompanied
by software that allows real-time manipulation of the sample and takes into account the experimental features of
the setup, such as aberration correction and LCD modulation. The LCD, a HoloEye LCR-2500, is the physical
support of the holograms, which are calculated using the fast random binary mask algorithm. The real-time
software achieves 12 fps at full LCD resolution (including aberration correction and modulation) when run on a
Pentium IV HT, 3.2 GHz computer.
Digital holography enables the creation of multiple optical traps at arbitrary three-dimensional locations and spatial light modulators permit updating those holograms at video rates. However, the time required for computing the holograms makes interactive optical manipulation of several samples difficult to achieve. We introduce an algorithm for computing holographic optical tweezers that is both easy to implement and capable of speeds in excess of 10 Hz when running on a Pentium IV computer. A discussion of the pros and cons of the algorithm, a mathematical analysis of the efficiency of the resulting traps, as well as results of the three-dimensional manipulation of polystyrene micro spheres are included.
We present an educational resource based in an optical software package for undergraduate students. It consists in a web based textbook with several applets for illustrating the theory and simplify the teaching tasks in the classroom. These programs are also used as a method for self-learning in an on-line environment. Applets are written in Java language using the Java Network Launching Protocol (JNLP) for avoiding problems related with the use of specific browsers or java interpreter's versions.
We present an educational resource based in a virtual optical laboratory for undergraduate students. It consists in a web-based textbook with several applets to illustrate the theory and simplify the teaching tasks in the classroom. These programs can also be used as a method for self-learning in an on-line environment. Applets are written in Java language using the Java Network Launching Protocol (JNPL) for avoiding problems related with the use of specific browsers or Java interpreters versions.
In this work we present a generalization to complex transmittance objects of the Jared-Ennis algorithm for the generation of Synthetic Discriminant Function filters (SDFs). The original algorithm consists of the resolution of a nonlinear system of equations by means of an iterative procedure, including a phase adaptation of the filter. The method shown here takes into account the modulation of liquid crystal displays (LCD) both for scene and filter, generalizing the problem to the complex plane. Considering this new method gives a more realistic picture as the LCD modulation gives a complex distribution of the scenes instead of only real values as considered before. For instance, we use a high contrast configuration to display the scenes. Moreover, the addition of new parameters to the problem allows us to consider filters other than the phase-only one. In our case, we use a phase-mostly configuration to display the filter and the metric optimized is the maximum correlation intensity, as in the original method. Simulated results are presented for a two-class problem, as well as experimental results obtained in a VanderLugt correlator. The filters produce the desired correlation response in both cases.