Description
The OM 72 department of the SPA "Crystal" produces and supplies a Group of optical fluoride crystals (especially valuable for combating chromatic aberrations):
- optical crystals of lithium fluoride LiF;
- optical crystals of calcium fluoride CaF2;
- optical crystals of barium fluoride BaF2.
These optical materials ("special crowns" with particularly low dispersion, high Abbe numbers) paired with "special flints" (with large dispersions, small Abbe numbers) are radical means for apochromatization of high-resolution lens optics with the most perfect image.
Useful not only for achromates, but also for apochromates*: eliminate not only primary, but also secondary chromatic position aberrations.
Field of application
In optical and polarization microscopy, spectroscopy, in lens construction, photo and film equipment, projection equipment and astrooptics, in combination and step-by-step animation installations (for microchips), in converters and amplifiers, splitters, modulators and storage devices, in laser technology…
To determine the requirements for optical crystalline materials, the categories established by GOST 23136 "Optical materials. Parameters".
Technical requirements
The technical requirements for each specific material are set out in the regulatory and technical documentation:
- for lithium fluoride crystals optical OST 3-6537-89;
- for calcium fluoride crystals optical OST 3-6304-87;
- for barium fluoride crystals optical OST 3-3992-77;
Blanks of optical fluoride crystals are obtained by growing in the form of disks, or rectangular plates obtained from them by mechanical cutting:
| Working range of the spectrum | Diameter (largest side) | Thickness |
|---|---|---|
| Ultraviolet, Visible, Infrared | 20, 30, 40 mm | 5, 10, 15 mm |
| Ultraviolet, Visible, Infrared | 50, 60, 70, 80, 100, 120, 150, 180 mm | 10, 15, 20, 25, 30, 35 mm |
| Infrared | 200 mm | 20, 25, 30, 35, 40 mm |
| Infrared | 220 mm | 20, 25, 30, 35, 40, 45 mm |
| Infrared | 250 mm (in agreement with the manufacturer) | 20, 25, 30, 35, 40, 45, 50 mm |
* APOCHROMAT - optich. the system, which differs from the achromat by a more perfect correction of chromatic aberrations, and primarily by correcting the secondary spectrum, is manifested in the mismatch of the plane of the sharp image for rays of a certain wavelength with images combined as a result of achromatization for rays of wavelengths and at . A radical means for the apochromatization of lens optics. systems is the application of a pair of optical. materials with significantly different variances and equal or close in numerical values include. partial variances . Such properties are possessed, in particular, by a pair: fluorite and glass from the "special flint" group. A. In comparison with achromates, they are either used in a wider range of the spectrum, or with the same spectral range they create a more perfect image. Naib. A. are widely used as lenses for microscopes.
