Spectroscopy of microscopic samples
The microspectrophotometer is a scientific instrument used to measure the spectra of microscopic samples. For example, an engineer in a semiconductor facility will use it to measure the thickness of thin films while a forensic scientist will use one to analyze the dye in a single textile fiber, shown on the left, or a chemist will use it to measure the spectrum of a nanocrystals. CRAIC Technologies™ builds a microspectrophotometer that combines a UV-visible-NIR optical microscope with a UV-visible-NIR range spectrophotometer. While a standard spectrophotometer is designed to measure samples on the order of 1 x 1 centimeters, the microspectrophotometer is able to measure samples on the order of 1 x 1 micrometers...much smaller than the thickness of a human hair.
As shown in the diagram on the left, the instrument combines a UV-visible-NIR range optical microscope with a UV-visible-NIR range spectrophotometer. In this figure, the instrument is configured for transmission microspectroscopy. The light from the lamp housing is focused onto the sample on the microscope stage (I0). The light that is transmitted through the sample, is collected by the objective (I) and focused onto the spectrophotometer entrance aperture.
There are also different types of microspectrophotometers. Some of these instruments are designed to be added to standard microscopes or probe stations, such as the 508 PV™ microscope spectrophotometer, while others are fully integrated, purpose built instruments such as the 20/30 PV™ microspectrophotometer. As such, microspectrophotometers have greater spectral ranges, better results and a number of features that are not possible with add-on units.
Why use a Microspectrophotometer?
The microspectrophotometer allows the scientist or engineer to acquire spectra of extremely small sample areas non-destructively and without physically touching the sample. Measurements can be made while light is transmitted through the sample, reflected from it, scattered from it or even when the sample is made to emit light: as shown in the image OLED pixels to the left. The UV-visible-NIR range is especially important as more substances...even colorless ones...absorb in the UV than in the visible and infrared regions. Therefore, a UV microscope spectrometer is very useful for analysis of most samples for any application.
Microspectrophotometers are easily employed in many different fields and are found in both scientific laboratories and production facilities. In the production environment, for example, they are used for quality control of everything from color masks in flat panel displays to the thickness of films on semiconductor integrated circuits. Microspectrometers are used by analytical laboratories to identify and quantify microscopic samples ranging from the microfluidic kinetics, matching fibers or paints by a forensic chemist, the qualification of gems or coal by a geologist, the determination of the color of ink or paint by a process chemist and even the analysis of great works of art by conservators. As such, the microspectrometer is a highly flexible instrument with many different applications.