- Photodiodes (including avalanche and PIN photodiodes) - Silicon and InGaAs
- Phototransistors - photodiode-amplifier combinations - from PerkinElmer and TT Optek
- Infrared detectors - from Judson Technologies, covering the whole IR spectrum
- Photon counting modules - from PerkinElmer, based on APDs or CPMs
- Channel photomultipliers - ultrasensitive optical detectors from PerkinElmer
Fast, Efficient Solutions for Low Level Light Detection in Medical Applications
Avalanche photodiodes (APDs) provide higher sensitivity than standard photodiodes, offering a combination of high speed and high sensitivity unmatched by PIN detectors, and quantum efficiencies at >400nm unmatched by PMTs. An APD differs from a PIN photodiode by providing internal photo-electronic signal gain. APDs are ideal for extreme low-level detection and photon counting, and are generally recommended for high bandwidth applications or where internal gain is needed to overcome high preamplifier noise. PerkinElmer offers a broad range of APDs in a variety of sizes, providing detection from 220nm to 1700nm and with additional pre-amplifier and filter options to tailor the device to meet specific requirements.
Channel Photomultipliers (CPMs) offer a new technology for more accurate and efficient photon detection. PMTs have severe limitations, and CPMs exceed the capabilities of PMTs by eliminating many of the disadvantages. CPMs have a simpler structure, and operate with far less background noise, than PMTs. In the CPM, the vacuum channel is virtually silent, and dark counts originate from the photocathode alone. The lower background level of a CPM results in a high dynamic range and significantly better detection limits. PerkinElmer CPMs are available in 3 sizes, and devices in each range are optimised in their sensitivity to detect wavelengths from near UV to IR (115nm to 900nm).
Silicon avalanche photodiode based SPCMs are successful due to their ability to detect from a few photons per second up to several million. The SPCM also has extremely high single-photon detection efficiency, and is much more sensitive than the PMT in the visible range. The SPCM-AQR is a self-contained single photon counting module which detects single photons of light over the wavelength range from 400nm to 1060 nm, and the SPCM-AQ4C is a 4-channel version with each channel independent from the others. The range also includes RoHS compliant modules. Applications include photon-correlation spectroscopy, adaptive optics, ultra-sensitive fluorescence and particle sizing.
Recent developments in optical detector technology have enabled the Silicon photomultiplier (SiPM), a low-light detector with high gain, wide dynamic range, very low dark current, low operating voltage, small form factor, high uniformity and excellent stability. A SiPM device is an array of small area avalanche photodiodes, connected in parallel, each capable of detecting a single photon. SiPMs have been developed to replace traditional PMTs, with superior advantages in size, cost, durability, insensitivity to magnetic fields and low operating voltage, enabling systems to be more compact, faster, handheld and portable. In many applications, they will simply be state-of-the-art detectors in confocal microscopy, chemiluminescence, bioluminescence, fluorescence analysis, flow cytometry, DNA sequencing and biochemical sensors. However, the ability to operate in a magnetic field makes them ideal for PET scanners and high energy Physics experiments.
Pacer is now exploring this exciting area of low light detectors. If you have applications that require the most up-to-date detection regime, please give us a call.
The Pacer portfolio includes products from PerkinElmer, Kodenshi, TT Optek, TAOS and Judson Technologies.
