Research and commercial application of confocal microscopy has witnessed tremendous development in recent years. In the confocal arrangement, the sample of interest (a biological tissue specimen or a spot on a micro-array) may be illuminated with white light or laser wavelengths relayed through a high NA imaging objective to realize a small focal volume. A fluorescent marker within the illuminated sample volume gives rise to the signal of interest. In the light collection optical path exists a pinhole, or confocal, aperature. This arrangement allows for isolation of fluorescence within the image plane and also reduction of background signal. The enhancement of signal to noise made possible by the confocal aperature allows for detailed 3D scanning of complex biological specimens or fast scanning of high-density microarrays.

In terms of light detection, a detector with excellent quantum efficiency and fast response is necessary because of the small illumination volume, weak intensity of the fluorescence, and high scanning speed. Wavelengths of 400 to 500 nm are typically of interest, although response at longer wavelengths may also be important with methods such as FRET. Photomultiplier tubes are ideally suited to confocal microscopy demands, and APD modules and CCD cameras are also commonly used. The ideal detector choice depends on the sample and imaging requirements of the application.

• H9305-03 compact photosensor module: contains 13 mm diameter side-on PMT and power supply circuit. Spectral response from 185 to 900 nm.
• H7422-50 photosensor module: metal package PMT with cooler. Spectral response from 380 to 890 nm. Requires modified protection circuit for this application.
• H7422-40 photosensor module: metal package PMT with cooler. Spectral response from 300 to 720 nm. Requires modified protection circuit for this application.
• H7421-50 photon-counting module: PMT with GaAs photocathode. Spectral response from 380 to 890 nm.
• H7421-40 photon-counting module: PMT with GaAsP photocathode. Spectral response from 300 to 720 nm.
• R6357 13 mm side-on PMT: spectral response from 185 to 900 nm.
• R3896 28 mm side-on PMT: includes high-sensitivity multialkali photocathode with spectral response from 185 to 900 nm.
• Avalanche photodiode modules: a wide variety of modules, each offering easy use of APD sensors by a simple DC power supply connection. Built-in temperature control circuit keeps APD gain constant.
• ImagEM electron multiplier CCD camera (C9100-13): wide dynamic range, high-speed readout, and high signal-to-noise ratio. Provides two readout modes, EM-CCD readout and normal CCD readout.

Please contact us for information on other products which can be used for this application.