Invar Lens Barrel for Microscope Objective Focus Stability
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Solution Overview
Problem
Conventional inverted microscopes experience focus shifting due to thermal expansion of the objective lens barrel, leading to an inability to maintain a clear image when the temperature increases from light or power sources, or air conditioning use.
Innovation Solution
An objective lens with a lens barrel made from invar-type material and a fitting mechanism featuring a male screw on the outer circumference, which connects to a nosepiece with a female screw, reducing thermal expansion and maintaining focus stability across different magnifications and numerical apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lens barrel is used, then the objective lens can be easily manufactured, but thermal expansion causes focus shifting when temperature increases
Solution Approach 1:
The patent changes the material parameter of the lens barrel from conventional materials to invar-type material, which has a very low thermal expansion coefficient. This parameter change resolves the thermal expansion issue while maintaining manufacturing feasibility, as invar is a well-established alloy suitable for precision optical applications.
Solution Approach 2:
The patent employs invar-type material, which is a composite alloy consisting primarily of iron and nickel (typically 64% Fe, 36% Ni). This composite material combines the benefits of low thermal expansion with mechanical strength and machinability, effectively resolving the contradiction between thermal stability and manufacturability.
2Ease of operation
If the male screw is positioned at the tip portion, then attachment is simplified, but focus shift occurs due to thermal expansion of the lens barrel
Solution Approach 1:
The patent changes the positional parameter of the male screw from the tip portion to the outer circumference of the lens barrel. This positional change allows the connection point to be away from the optical axis while maintaining attachment ease, and combined with the invar material, eliminates focus shift caused by thermal expansion.
Solution Approach 2:
The patent moves the male screw from a position on the optical axis (tip portion) to the outer circumference, effectively changing the spatial dimension of the connection point. This dimensional change allows the connection to be made at a location that is thermally stable while maintaining ease of attachment operations.
3Adaptability or versatility
If objective lenses with different magnifications are fitted to the nosepiece, then versatility is improved, but parfocality variation occurs
Solution Approach 1:
The patent designs the male screw on the outer circumference with standardized dimensions that can be universally applied to objective lenses with different magnifications and numerical apertures. This universal design allows multiple lens types to be fitted to the same nosepiece while maintaining consistent parfocality through the standardized connection geometry.
Solution Approach 2:
The patent standardizes the positional parameter of the male screw on the outer circumference, creating a consistent reference point for all objective lenses. This parameter standardization ensures that lenses with different optical characteristics can be mounted with consistent positioning, thereby maintaining parfocality across the lens suite.
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 solution effectively minimizes focus shift caused by thermal expansion, ensuring clear imaging and easy attachment of objective lenses with varying magnifications, while maintaining parfocality and allowing for precise control of environmental temperature, especially when imaging living cells.
Implementation Method 1
a distance between the objective lens and the stage may be varied by thermal expansion of the lens barrel of the objective lens held by a nosepiece resulting in focus shifting
Implementation Method 2
the lens barrel is made from an invar-type material with a low thermal-expansion coefficient
Data Source
AI summary
An objective lens to be fitted into a fitting hole of a nosepiece of a microscope includes an imaging lens that is composed of a plurality of lens groups, and a lens barrel that holds the imaging lens. The lens barrel is formed with a fitting portion that is fitted to the fitting hole of the nosepiece and provided at an outer circumference of a tip portion side away by a given distance from the tip portion where a first lens group in the imaging lens is held, and a mount surface that comes into contact with a contact surface of the fitting hole of the nosepiece upon fitting at the fitting portion. The nosepiece is equipped with the objective lens. The inverted microscope is equipped with the nosepiece fitting the objective lens.