Microscope Autofocus Using Dual Z-Position Detectors
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Solution Overview
Problem
Existing microscope devices with autofocus functionality lack speed and accuracy in focusing and maintaining focus under varying thermal conditions, especially when the sample is rapidly moved relative to the objective.
Innovation Solution
A microscope device with a drive feedback control loop that combines information from an absolute z-position detector and a relative z-position detector to rapidly adjust the focus drive actuator, using a collimated autofocus light beam to determine the absolute z-position and adjust the focus drive to achieve precise and fast focusing, capable of recalibrating in real-time to maintain focus even with rapid sample movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single relative z-position detector is used to determine focus position, then the device structure is simple, but the focusing speed and accuracy are insufficient under rapid sample movement and thermal drift conditions
Solution Approach 1:
The patent combines an absolute z-position detector (measuring actuator position) with a relative z-position detector (measuring sample position) into a unified focus control system. The central control unit integrates signals from both detectors to calculate the absolute distance to the target z-position, achieving fast and accurate focusing by merging the advantages of both detection methods.
2Measurement precision
If the focus system relies solely on relative position detection, then the system is simple, but it cannot maintain nanometer precision under thermal drift and rapid sample movement
Solution Approach 1:
The patent implements a drive feedback control loop where the central control unit continuously receives position information from both absolute and relative z-position detectors, calculates the distance to the target z-position, and directs the actuator to adjust the focus. This closed-loop feedback system maintains nanometer precision even under thermal drift and rapid sample movement conditions.
3Productivity
If the autofocus system uses traditional focusing methods, then the structure is simple, but it cannot achieve both fast focus acquisition and continuous precision maintenance
Solution Approach 1:
The patent employs dynamic focus control by continuously adjusting the actuator position based on real-time feedback from both detectors. The system can rapidly acquire focus by moving the actuator to the calculated target position and then continuously maintain precision by making small adjustments in response to thermal drift and sample movement, achieving both fast acquisition and reliable maintenance.
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
Enables the microscope to find focus within a few hundred milliseconds and maintain it with nanometer precision, allowing for high-precision focus-hold operations even when the sample is moved rapidly, effectively compensating for thermal drift and maintaining focus with recalibration frequencies adjusted according to need.
Implementation Method 1
the autofocus light is focused onto the substrate by the microscope objective
Implementation Method 2
the collimated outgoing autofocus light beam reaches a predetermined threshold position on the relative position detector
Data Source
AI summary
A microscope device includes an objective (1); an actuator (6) for adjustment of a distance in a focusing direction z, an absolute z-position detector (7) for measuring a z-position. The device further includes an autofocus light source (11); a first optical arrangement (12, 13) for generating a focused spot (31) of autofocus light from the light source in the backfocal plane (14) of the objective (1) at a position offset from the optical axis of the objective by a lateral offset distance (d) The objective generates a collimated incoming beam (22) of autofocus light, which is directed at an oblique angle (β) relative to the optical axis (15) of the objective onto the substrate. The microscope may further include a second optical arrangement (13, 16) for generating collimated outgoing beams (34, 35) of autofocus light and directing the collimated outgoing beam onto a detector-array (17).