Through A Glass Brightly

Have you ever wanted to find a rare signal in a large field? How about a weak signal in a field with bright spots? Or what if you didn't know what to expect but simply wanted to see what was in a sample? LightForm's unique Prism and Mirror Imaging Spectroscopy System (PARISS) can do all these things and do them at a fraction of the cost of conventional imaging spectrometers. PARISS is a patented imaging spectrometer that acquires emitted light from a specimen on any microscope and sends it to a

Nov 24, 1997
The Scientist Staff

Have you ever wanted to find a rare signal in a large field? How about a weak signal in a field with bright spots? Or what if you didn't know what to expect but simply wanted to see what was in a sample? LightForm's unique Prism and Mirror Imaging Spectroscopy System (PARISS) can do all these things and do them at a fraction of the cost of conventional imaging spectrometers.

PARISS is a patented imaging spectrometer that acquires emitted light from a specimen on any microscope and sends it to a curved prism that displays spatially resolved spectral content and a video image of the sample. In contrast to conventional systems that use filters to collect specific signals, PARISS collects the entire spectrum of light from 365 to 800 nm simultaneously along a slice or sector in the field of view. One hundred spectral objects (structures, features, or background, each 0.5 micrometer in height at 40X) can be collected simultaneously from a slice, after which the stage can be translated and the process repeated. Sequential acquisitions across the field of view can generate a complete profile of the sample. Alternatively, the instrument can be asked to remember a spectrum and indicate when it finds it. Data from an unlimited number of segments, the size of which varies with the magnification of the objective and the slit width of the spectrometer, can be collected in as little as 10 to 200 msec/slice, depending on light intensity. Because the image is sectored, local areas of intense light can be eliminated from the field, enabling the acquisition of nearby weak signals.

Sputum smear containing fluorescent auramine/rhodmine stined tuberculosis bacteria
There are numerous advantages to PARISS, including the following:
  • The ability to acquire all spectra at once reduces the potential for photo-bleaching, which is potentially a problem when multiple fluorescent probes are being used.
  • The system can locate and quantitate any emitting object by its spectrum and map its location on a video image.
  • The user can be alerted if a spectrum indicative of a special feature is found.

With a price tag of $15,000, the PARISS System includes two CCD cameras, and a neural network software package for analyzing the data and presenting the video image. The instrument can be used directly with just about any microscope with a C mount, and eyepiece adapters make the instrument compatible with other microscopes as well. The neural network both collects and sorts spectra according to user-defined thresholds, recognizes spectral objects and plots their location in the specimen.

Dr. Sandor Vari, Research Scientist at the Laser Research and Technology Development Center at Cedars Sinai Medical Center, Los Angeles, sees the PARISS System as a tremendous help in the area of pathology and medical diagnostics. While being user-friendly, adaptable to most microscopes, and compact, the PARISS System actually provides more detailed information than more expensive scanning systems, according to Dr. Vari. He has used the device to scan for and quantitate the presence of TB in auramine/rhodamine-stained human sputum samples (see figure). The system is presently applicable to microscopic samples on a motorized stage; however, Dr. Vari sees the day when it can be applied to real-time diagnostics using any of a variety of microscopic or telescopic instruments. In this way the ability to scan and collect large amounts of data based on tissue fluorescence, reflectance, or absorption will be enhanced.

Applications of the PARISS System exist within both the basic research and clinical environments. While providing much the same kind of information of imaging systems costing 4 to 5 times the price, PARISS provides an inexpensive "workhorse" tool to enable the unique spectral characteristics of tissue or other materials to be quickly revealed in real time. Being able to see the "spectral morphology" of living cells and tissues will provide a completely novel way of looking at cells. In the clinical arena, LightForm has received a grant to put the PARISS system on an endoscope to enable physicians performing exams to confirm or "guide the eye" with the extra degrees of freedom that spectal characteristics offer.

For more information, contact LightForm at 908-281-9098.