An electron microscope uses high energy electrons rather than light (which is used in conventional optical microscopes), to form an image. A thin beam of high energy electrons is produced and bombards the specimen thus producing scintillation which is captured and measured though a scintillation counter. Since the electron beam scans the specimen line by line and builds the image, it is called a scanning electron microscope. The advantages to using the SEM in-place of an optical microscope are that the SEM has a large depth of field, which allows it to create a 3-dimensional image of the sample. Since the wavelength of an electron beam is less than that of light, the SEM produces images of high resolution, which means that closely spaced features can be examined at a high magnification. Preparation of the samples is relatively easy since most SEMs only require the sample to be conductive. The combination of higher magnification, larger depth of focus, greater resolution, and ease of sample observation makes the SEM one of the most heavily used instruments in research areas today.
IONICS, India’s leading high voltage power supplies specialists have developed a very compact power supply unit for the scanning electron microscope that is being used by one of India’s top research agencies. The entire unit consists of the following high voltage power supplies.
- 30kV power supply
- Filament supply
- 10kV power supply for scintillator
- 1.5kV power supply for the PMT
- Collector power supply
The filament power supply is used to heat up a filament that emits electrons. The electron that gets emitted is passed through a fine hole in a metallic cup which is called as wehnelt. This way the electrons get concentrated into a thin beam and a 30kV power supply is used to accelerate the electrons to the desired velocity. The scintillator and the PMT together form the scintillator counter and are used to measure the signature emission of the sample. These are also powered by two HV power supplies.
The HV power supplies that were used, were highly regulated (voltage regulation was better than 50 parts per million for both line and load and current regulation was better than 100 parts per million). In addition to that, the power supplies were highly stable (with stability better than +/- 100 parts per million). In order to make it compact, all the power supplies were housed in a single 15” rack.
The entire unit was designed and developed in-house at a fraction of the cost of imported power supplies. All the power supplies are working flawlessly, generating beautiful images of the specimen.
This is a small step in developing products that are import substitutes and IONICS team is proud of this achievement.
Visit us at www.ionics.co.in for more details.