Macro Lens System Aberration Correction via Segmented Focusing
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Solution Overview
Problem
Conventional macro lens systems fail to adequately correct chromatic aberrations during close-distance imaging, leading to deteriorated operability and high-speed focusing issues due to large lens diameters and significant longitudinal chromatic aberrations.
Innovation Solution
A macro lens system comprising a specific configuration of refractive power groups, including a first positive lens group, a second negative lens group, a third positive lens group, a fourth negative lens group, and a fifth positive lens group, with the second, fourth, and fifth groups independently moving along the optical axis during focusing, and satisfying certain refractive index and Abbe's number conditions to minimize aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first lens group with large diameter is moved for focusing, then close distance imaging capability is improved, but focusing speed deteriorates due to great weight
Solution Approach 1:
The lens system is divided into multiple lens groups (first through sixth) with different functions. The first lens group maintains large diameter for close-distance imaging capability, while smaller lens groups (second, fourth, fifth) are designated for focusing movements, segmenting the functions between size and mobility requirements.
Solution Approach 2:
Instead of moving the large first lens group toward the object side for focusing (conventional front focusing), the patent inverts the approach by moving smaller lens groups (second, fourth, fifth) in various directions to achieve focusing, thereby maintaining close-distance capability without the weight penalty of moving the largest group.
2Measurement precision
If the first lens group is moved toward the object side for close distance imaging, then imaging magnification is improved, but operability deteriorates
Solution Approach 1:
The focusing function is segmented from the large first lens group and assigned to smaller lens groups (second, fourth, fifth). This allows the first lens group to remain in a more favorable position for close-distance imaging while smaller groups handle the focusing movements, improving operability.
Solution Approach 2:
Smaller lens groups act as intermediaries to achieve focusing effects without requiring the large first lens group to move extensively toward the object, thereby maintaining both high magnification capability and good operability.
3Measurement precision
If conventional macro lens configuration is used, then close distance imaging is achieved, but longitudinal chromatic aberrations become great
Solution Approach 1:
Different lens groups are assigned specific refractive power characteristics (positive or negative) to address different optical requirements. The alternating positive-negative configuration allows local correction of chromatic aberrations while maintaining overall close-distance imaging capability.
Solution Approach 2:
The patent uses composite lens structures including cemented lenses (e.g., second lens group with negative and positive lenses cemented, fourth lens group with similar structure) to correct chromatic aberrations through the combination of different glass materials with complementary dispersion properties.
4Object-affected harmful factors
If multiple lens groups are moved for focusing, then aberration suppression is improved, but device complexity increases
Solution Approach 1:
The focusing function is divided among three separate lens groups (second, fourth, fifth) that can move independently. This segmentation allows each group to be optimized for specific aberration corrections while sharing the focusing workload, managing complexity through functional distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The macro lens system effectively corrects chromatic aberrations at close distances, improving image quality and enabling high-speed focusing by reducing the weight and outer diameter of moving lens groups, thus enhancing operational efficiency.
Implementation Method 1
a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, and a sixth lens group G6 having a negative refractive power
Implementation Method 2
at least one positive lens to satisfy Conditional Formulae (1) and (2) below: N1d>1.65 and ν1d>60.0; the second lens group to have a cemented lens formed by a negative lens and a positive lens, and to satisfy Conditional Formula (3) below: ν2dn−ν2dp>20.0
Data Source
AI summary
A macro lens system includes, in this order from an object side: a positive first lens group; a negative second lens group; a positive third lens group; a negative fourth lens group; a positive fifth lens group; and a negative sixth lens group. The first lens group is constituted by three lenses. The second lens group, the fourth lens group, and the fifth lens group are independently moved in the direction of the optical axes thereof when focusing from an object at infinity to an object at a most proximate distance. The second lens group moves toward the image side and the fourth lens group moves toward the object side when focusing from an object at infinity to an object at a most proximate distance.