Infrared confocal microscope

The infrared confocal microscope described here is a component part of the final composite acoustic-infrared-visible confocal microscope system to be constructed on a common base to enable visualisation and comparison of the images, obtained by these three different imaging modalities, of the same tissue. The capability of near infrared light to examine subsurface structures, with minimal preparation, has been exploited in the development of the confocal scanning infrared microscope. Conventional microscopy techniques need advanced preparation of the tissue such as embedding, sectioning and staining, to enable visualisation of the structures within the tissue. This generally involves a wait of about 24 to 48 hours before an attempt is made to look at the tissue conventionally. A spectral scan of the breast tissue in vitro, shows optical windows at 700 nm, 1,000 nm, and 1,250 nm to 1,350 nm. These wavelengths have been used in the prototype confocal scanning infrared microscope, to examine up to 3 mm thick, formalin fixed unstained and immune-stained, breast tissue slices. The confocal scanning infrared microscope has been constructed on an optical bench with standard optical components and a monochromator has been used as the infrared source enabling various wavelength studies. The mechanical scanning stage control, data acquisition, image reconstruction and analysis features are all microcomputer based. The principle of confocality offers the opportunity of optical sectioning of the tissue enabling three dimensional visualisation of structures. It is shown how the sectional slices so obtained can be put together to form a 3D database.