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Slit Lamp Continuous Improvement Of Quality, The Application Of Increasingly Extensive
Jun 23, 2017

1. principle

In the process of absorbing ultraviolet and visible electromagnetic radiation, the molecules are excited to move to the excited electron state, most molecules will be through the collision with other molecules in the way of heat dissipation of this part of the energy, some molecules in the form of light to emit this part Energy, the wavelength of the emitted light is different from the wavelength of the absorbed radiation.

The latter process is called photoluminescence. Molecular luminescence includes Slit Lamp, phosphorescence, chemiluminescence, bioluminescence and scattering spectroscopy. The analytical method based on the Slit Lamp measurement of the compound is called molecular Slit Lamp spectroscopy.

The light emitted by the light source through the cutter to make it intermittent light, through the excitation light monochromator into monochromatic light, the light is the excitation of Slit Lamps. Slit Lamp emitted by the Slit Lamp under the excitation light, through the monochromator into monochromatic Slit Lamp after irradiation on the photomultiplier tube, by the occurrence of photocurrent through the amplifier amplification to the recorder. An excitation, a firing, using a double monochromator system that can measure the excitation spectra and Slit Lamp spectra, respectively.

2. classification

Slit Lamp spectrometer is the basic equipment for determining the luminescent properties of materials. General fluorescent spectrometer can be divided into three kinds:

(1) basic type: 200-800 nm in the UV visible band steady-state spectrometer.

(2) Extended type: UV-visible-near-infrared steady-state spectrometer covering 200-1700 nm band.

(3) integrated type: covering the above two bands, while measuring the transient spectrum of the spectrometer.

3. The main purpose

(1) Slit Lamp excitation spectra and Slit Lamp emission spectra;

(2) Synchronous Slit Lamp (wavelength and energy) scanning spectra;

(3) 3D (Ex Em Intensity);

(4) Time Base and CWA (fixed wavelength single point measurement);

(5) Slit Lamp life measurement, including life resolution and time resolution;

(6) computer acquisition of spectral data and processing data (Datamax and Gram32).

4. Development History

The first record of the phenomenon of Slit Lamp is the 16th century Spanish physician and botanist N.Monardes, in 1575 he mentioned in a known as "LignumNephriticum" wood chips in the aqueous solution, showing a very lovely sky blue The In the 17th century, well-known scientists such as Boyle (1626-1691) and Newton (1624-1727) observed Slit Lamp again. After the Slit Lamp has aroused the interest of many scientists, Slit Lamp analysis methods are also more and more applied to biological and chemical analysis.

Of course, the development of Slit Lamp analysis methods, and the development of instrument applications are inseparable. In general, the Slit Lamp spectrometer since its inception through three stages of the development process:

(1) manual;

(2) automatic scanning;

(3) computerized.

1. light source

Early Slit Lamp spectrophotometer with low mercury mercury lamp capable of producing very narrow mercury lines. Using high-pressure mercury lamps, the lines are widened and there are high-strength continuous zones. However, the determination of a complete excitation spectrum requires a lamp capable of emitting higher intensity light radiation from visible to ultraviolet ranges. Xenon arc lamps are suitable for this condition, so it is currently the most widely used light source in fluorescent spectrophotometers.

2. Monochromator

The function of the monochromator is to decompose the continuous spectrum emitted by the light source into monochromatic light and to "accurately" take out the light of a certain wavelength, which is the heart part of the spectrometer. The monochromator consists essentially of slits, dispersive elements and lens systems, where the dispersion element is a key component. The dispersive element is a combination of a prism and a reflective grating, or both, which can disperse the continuous spectrum into monochromatic light.

(1) Prism monochromator

Prism monochromator is the use of different wavelengths of light in the prism within the refractive index of complex light dispersion of monochromatic light. The size of the prism dispersion is related to the material and geometry of the prism. Commonly used prisms are made of glass or quartz. Visible spectrophotometer can use glass, it is suitable for ultraviolet, visible throughout the spectral area.

(2) grating monochromator

Grating as a dispersion element has many unique advantages. The grating can be defined as a series of equally spaced, equidistant parallel slits. The dispersion principle of the grating is based on the diffraction phenomena and interference phenomena of light. Commonly used grating monochromator for the reflection grating monochromator, which is divided into two kinds of plane reflection grating and concave reflection grating, the most commonly used is the plane reflection grating. The grating monochromator resolution is higher than the prism monochromator resolution (up to ± 0.2 nm), and it is available in a wavelength range that is wider than the prism monochromator and 80% of the incident light is in the primary spectrum. In recent years, the grating of the copy technology is constantly improving, its quality is constantly improving, and thus its increasingly widespread application.

(3) slits

The slit is an important part of the monochromator, which directly affects the resolution. The smaller the slit width, the better the monochromaticity, but the light intensity also decreases.





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