Portable Optical Spectrum Analyzer (POSA) / Portable Fourier Transform Infrared Spectrum Analyzer (PISA)

The main objective of the POSA DWDM project (Contract No. IST-2001-34850) was to develop a new, portable optical spectrum analyzer (POSA), suitable for both field and laboratory conditions for the task of maintaining and troubleshooting DWDM (dense wavelength division multiplexing) system's components and networks.

Due to the crash in the telecommunication market, the industrial interest in new concepts for optical spectrum analyzers had decreased. In connection with that the POSA project partners decided to change the project objectives and to direct the efforts towards using already developed main results of the project for a development of a new product - Portable Fourier transform Infrared Spectrum Analyzer (PISA) - for spectroscopic purposes. The new instrument should have properties attractive in the market place. It should have features not yet available in commercially offered spectrometers, e.g. true portability, low power usage, adaptable to specific market requirements. A number of components were used which had already been developed within the POSA project.

To be convenient for both the use in field and laboratory conditions, an optical spectrum analyzer has not only to have a high dynamic range and a high spectral resolution, but also has to be rugged and compact. In order to achieve these key technological objectives, the project was divided into four major parts:

• Detailed specification
  Based on the state-of-the-art situation on the DWDM optical spectrum analyzer market, detailed specifications were developed.

• High resolution double-beam interferometer
  A high-resolution double-beam interferometer - the heart of the POSA system - and the electronics of the instrument were designed and implemented. Tolerance calculations for the optical components of the instrument and for interfacing POSA with the DWDM system were carried out. Hardware, software, electronics, and the data acquisition platform were integrated in order to build the prototype.

• Data acquisition module and sampling algorithm
  This part of the project focused on the design of a new, unequally spaced sampling technique, helping to reduce the data handling time and data storage requirements. Furthermore, the data acquisition system for the spectrum analyzer was developed. It had to be resistant against the worst anticipated field conditions and had to provide long-term stability.

• Test and calibration
  The developed prototype was evaluated and tested in order to investigate the performance of the whole POSA instrument.

With Bruker Optik, a company working in the field of spectroscopy entered the project. Now there is a number of companies active in this market and there are quite a number of instruments with different technical solutions already available. They cover most needs in the laboratory. What are missing, are small rugged and portable instruments with limited capabilities, but with capabilities which are tailored to solve the problem. Missing are truly portable spectrometers for gas or vapour analysis, portable spectrometers for forensic analysis, portable spectrometers for quality control in the industry. All these spectrometers, while tailored to solve different problems have in common portability, good sensitivity and ease of use.
As the basic concept of an optical spectrum analyzer is similar to that of a spectrometer, concepts and parts already available from POSA are now used to develop a prototype of a portable infrared spectroscopic analyzer which demonstrates the essential features of such a unit.

The purpose of the amended project is thus to develop a new, portable Fourier transform infrared spectrum analyzer (PISA), suitable for both field and laboratory conditions for the tasks of infrared spectroscopy. Features:

1. The instrument will be small, light and portable, features which are currently not available for Fourier transform infrared optical spectrum analyzers and at the same time it will be rugged and compact due to its unique optical design.


2. The instrument will use components specially adapted for portable instrumentation, e.g. low power source and low power electronics, e.g. inexpensive delta-sigma converters which have low power consumption.


3. A compact and rugged interferometer will be deduced from the POSA design, which is well adapted to the resolution and throughput requirements of the spectrometer.


4. Size, weight, reliability and low power requirements suggest the use of laser diodes instead of bulky HeNe gas lasers.

As the project's aim is to develop equipment that is already available on the market in another format, patenting of the novel techniques developed in this project is considered to be very important. During the patent application period, public dissemination of information concerning the patent was not possible. Thus, the patent application determined all other dissemination activities. By now, the preliminary examination report on the european patent application No. EP02700192.4 "Scanning Interferometer" has been received. Six claims have been accepted.

In general, dissemination activities will now be focused on two different audiences, the scientific community and the end-user community. While the dissemination within the scientific community - e.g. presentations at scientific conferences - shall put emphasis on single innovative setups and procedures, the dissemination in the end-user community shall highlight the benefits of the resulting product.