Precision Aplanatic
Achromatic Doublets
Paralight Optics offers a variety of custom achromatic optics with customer-defined sizes, focal lengths, substrate materials, cement materials, and coatings are custom-made. Our achromatic lenses cover the 240 – 410 nm, 400 – 700 nm, 650 – 1050 nm, 1050 – 1620 nm, 3 – 5 µm, and 8 – 12 µm wavelength ranges. They are available unmounted, mounted or in matched pairs. Regarding unmounted achromatic doublets & triplets line-up, we can supply achromatic doublets (both standard and precision aplanatic), cylindrical achromatic doublets, achromatic doublet pairs that are optimized for finite conjugates and ideal for image relay and magnification systems, air-spaced achromatic doublets that are ideal for high-power applications due to a greater damage threshold than cemented achromats, as well as achromatic triplets that allow for maximum aberration control.
Paralight Optics’ Precision Aplanats (Aplanatic Achromatic Doublets) are not only corrected for spherical aberration and axial color as the Standard Cemented Achromatic Doublets but also corrected for coma. This combination makes them aplanatic in nature and delivers better optical performance. They are used as laser focusing objectives and in electro-optical & imaging systems.
Features:
Benefits:
Minimization of Axial Chromatic & Spherical Aberration
Comparison to Standard Achromatic Doublets:
Be Optimized to Correct for Coma
Optical Performance:
Aplanatic in Nature and Delivering Better Optical Performance
Applications:
Laser Focusing and in Electro-Optical & Imaging Systems
Common Specifications:
Reference Drawing for
achromatic doublet
f: Focal Length
fb: Back Focal Length
R: Radius of Curvature
tc: Center Thickness
te: Edge Thickness
H”: Back Principal Plane
Note: For best performance when collimating a point source, generally the first air-to-glass interface with the greater radius of curvature (flatter side) should face away from the refracted collimated beam, conversely when focusing a collimated beam, the air-to-glass interface with the shorter radius of curvature (the more curved side) should face the incident collimated beam.
Parameters
Ranges & Tolerances
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Substrate Material
Crown and Flint Glass Types
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Type
Cemented Achromatic Doublet
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Diameter
3 - 6mm / 6 - 25mm / 25.01 - 50mm / >50mm
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Diameter Tolerance
Precison: +0.00/-0.10mm | High Precision: >50mm: +0.05/-0.10mm
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Center Thickness Tolerance
+/-0.20 mm
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Focal Length Tolerance
+/-2%
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Surface Quality (scratch-dig)
40-20 / 40-20 / 60-40 / 60-40
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Spherical Surface Power
3 λ/2
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Surface Irregularity (Peak to Valley)
Precison: λ/4 | High Precision: >50mm: λ/2
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Centration
3-5 arcmin / < 3 arcmin / < 3 arcmin / 3-5 arcmin
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Clear Aperture
≥ 90% of Diameter
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Coating
BBAR 450 - 650 nm
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Design Wavelengths
587.6 nm
Graphs
Focal Shift vs. Wavelength
Our achromatic doublets are optimized to provide a nearly constant focal length across a broad bandwidth. This is accomplished by utilizing a multi-element design in the Zemax® to minimize the chromatic aberration of the lens. Dispersion in the first positive crown glass of the doublet is corrected by the second negative flint class, resulting in better broadband performance than spherical singlets or aspheric lenses. The right-side graph shows the paraxial focal shift as a function of wavelength for the visible achromatic doublet with a focal length of 400mm, Ø25.4 mm for your reference.
