Achromatic Doublet 20mm Diameter 30.6mm Focal Length
DLB-20-30PM
Achromatic doublets are cemented achromats made of two different lenses (Low dispersion positive from crown glass and high dispersion negative from flint glass). The difference of dispersion and shape of both lenses are designed to minimize the chromatic aberrations in blue (486.1nm), green (546.1nm) and red (656.3nm). Therefore, these lenses are able to support the entire visible wavelength spectrum.
◦The spherical aberration of achromatic doublets is better than singlets and minimized at infinite conjugate ratios.
◦Achromatic Doublets are coated on both surfaces with a broadband multi-layer anti-reflection coating for the visible wavelength (400 − 700nm).
◦Set the positive part to the side of the incident parallel beam and put the negative part to the side of the focal point to minimize spherical aberration.
◦The difference in focal length of a lens at each wave length is Chromatic aberration and is due to “dispersion of the glass”, the change in refractive index of glass according to wavelength. This can be corrected by combining glasses with low and high dispersions. Spherical aberration is when a ray enters a lens farther from its optical axis and has a shorter focus than a paraxial focus.
◦Achromatic Doublets are coated on both surfaces with a broadband multi-layer anti-reflection coating for the visible wavelength (400 − 700nm).
◦Set the positive part to the side of the incident parallel beam and put the negative part to the side of the focal point to minimize spherical aberration.
◦The difference in focal length of a lens at each wave length is Chromatic aberration and is due to “dispersion of the glass”, the change in refractive index of glass according to wavelength. This can be corrected by combining glasses with low and high dispersions. Spherical aberration is when a ray enters a lens farther from its optical axis and has a shorter focus than a paraxial focus.
| Name | Achromatic Doublet 20mm Diameter 30.6mm Focal Length |
|---|---|
| Weight | 0.0090kgs |
| Standard Coatings Available | No |
| Guide |
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| Remark | - |
| Attention |
|
| Image Label | Achromatic Doublet 20mm Diameter 30.6mm Focal Length |
| Diameter φD | 20mm |
| Focal length | 30.6mm |
| Material | BK7, SF2 |
| Design wavelength | Blue: 486.1nm, Green: 546.1nm, Red: 656.3nm |
| Coating | Broadband Multilayer Antireflection Coating for the Visible |
| Cement | Ultraviolet Hardened Adhesive |
| Laser Damage Threshold |
0.3J/cm2 (Laser pulse width 10ns, repetition frequency 20Hz) |
| Surface Quality (Scratch-Dig) | 40-20 |
| Diameter φD | φ20mm |
| Focal length f | 30.6mm |
| Edge Thickness te | 6.8mm |
| Center Thickness tc | 10.9mm |
| Back focal length fb | 24.9mm |
| Centration | ＜1′ |
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DLB-20-30PM
€98.10
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Achromatic doublets are cemented achromats made of two different lenses (Low dispersion positive from crown glass and high dispersion negative from flint glass). The difference of dispersion and shape of both lenses are designed to minimize the chromatic aberrations in blue (486.1nm), green (546.1nm) and red (656.3nm). Therefore, these lenses are able to support the entire visible wavelength spectrum.
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