Point-of-use chemical analysis holds tremendous promise for a number of industries, including agriculture, recycling,
pharmaceuticals and homeland security. Near infrared (NIR) spectroscopy is an excellent candidate for these
applications, with minimal sample preparation for real-time decision-making. We will detail the development of a golf
ball-sized NIR spectrometer developed specifically for this purpose. The instrument is based upon a thin-film dispersive
element that is very stable over time and temperature, with less than 2 nm change expected over the operating
temperature range and lifetime of the instrument. This filter is coupled with an uncooled InGaAs detector array in a
small, rugged, environmentally stable optical bench ideally suited to unpredictable environments. The resulting
instrument weighs less than 60 grams, includes onboard illumination and collection optics for diffuse reflectance
applications in the 900-1700 nm wavelength range, and is USB-powered. It can be driven in the field by a laptop, tablet
or even a smartphone. The software design includes the potential for both on-board and cloud-based storage, analysis
and decision-making. The key attributes of the instrument and the underlying design tradeoffs will be discussed,
focusing on miniaturization, ruggedization, power consumption and cost. The optical performance of the instrument, as
well as its fit-for purpose will be detailed. Finally, we will show that our manufacturing process has enabled us to build
instruments with excellent unit-to-unit reproducibility. We will show that this is a key enabler for instrumentindependent
chemical analysis models, a requirement for mass point-of-use deployment.
While substantial progress has been made recently towards the miniaturization of Raman, mid-infrared (IR), and near-infrared
(NIR) spectrometers, there remains continued interest from end-users and product developers in pushing the
technology envelope toward even smaller and lower cost analyzers. The potential of these instruments to revolutionize
on-site and on-line applications can only be realized if the reduction in size does not compromise performance of the
spectrometer beyond the practical need of a given application. In this paper, the working principle of a novel, extremely
miniaturized NIR spectrometer will be presented. The ultra-compact spectrometer relies on thin-film linear variable filter
(LVF) technology for the light dispersing element. We will also report on an environmental study whereby the contamination
of soil by oil is determined quantitatively in the range of 0-12% by weight of oil contamination. The achieved
analytical results will be discussed in terms of the instrument's competitiveness and suitability for on-site and in-the-field
Narrow notch and multi-notch thin-film filters have applications in many fields. Raman spectroscopy and laser-based fluorescence instruments both desire filters that can remove one or more narrow spectral bands while maintaining high transmittance for light at adjacent wavelengths. Key figures of merit for notch filters include the width of the notch as a fraction of the blocked wavelength (narrower is better), the degree of suppression, and the overall transmittance of the filter.
Design approaches for narrowband notch and multi-notch filters are well-known, and include rugate or "quasi-rugate" designs. The manufacturing of these filters has proven to be challenging. The filters have to be very thick to achieve high suppression, and typically involve the deposition of gradient index layers or many very thin, discrete layers. Accurate spectral placement of the notches often requires extreme process control or post-deposition tuning of the filter.
JDSU has recently developed a design and manufacturing capability for single and multi-notch filters in the visible wavelength region where the notch width is less than 2% and the blocking levels are greater than OD 6. Designs for these types of filters can be 20 - 60 &mgr;m thick and consist of more than 1,000 layers. Our Ucp-1 high-rate magnetron sputtering platform with load-lock provides an inherently stable deposition process. This enables us to coat these challenging designs. In this paper, we present examples of both single and multi-notch filters that have 612 to 4410 layers and are 31 to 127 &mgr;m thick.
Results for a new compact 488 nm solid-state laser for biomedical applications are presented. The architecture is based
on a multi-longitudinal mode external cavity semiconductor laser with frequency doubling in a ridge waveguide fabricated in periodically poled MgO:LiNbO<sub>3</sub>. The diode and the waveguide packaging have been leveraged from telecom packaging technologies. This design enables built-in control electronics, low power consumption (≤ 2.5 W) and a footprint as small as 12.5 x 7 cm. Due to its fiber-based architecture, the laser has excellent beam quality, M<sup>2</sup> <1.1. The laser is designed to enable two light delivery options: free-space and true fiber delivered output. Multi-longitudinal
mode operation and external doubling provide several advantages like low noise, internal modulation over a broad frequency range and variable output power. Current designs provide an output power of 20 mW, but laser has potential for higher power output.