Laser Microscope PPD Beam Diameter Adjustment
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Solution Overview
Problem
Photon count loss occurs when strong light is incident on a Pixelated Photon Detector (PPD) due to uneven photon distribution across its detection elements, limiting the light-intensity range that can be detected.
Innovation Solution
A laser microscope apparatus with an adjusting mechanism that ensures the beam diameter of the light incident on the PPD is equal to its effective detection area, using a collimator lens and controller to adjust the beam diameter based on the objective lens's NA, thereby reducing photon count loss and widening the detectable light-intensity range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PPD is used in Geiger mode to detect ultraweak light at the single-photon level, then detection sensitivity is improved, but the number of photons that can be detected per unit time is limited to about 1 photon per pixel
Solution Approach 1:
The photodetector is divided into multiple pixels (e.g., 256 pixels) that operate independently in Geiger mode. Each pixel can detect single photons, and the total detection capability is the sum of all pixels, enabling both high sensitivity and high photon detection rate simultaneously
Solution Approach 2:
The invention transitions from single-pixel detection to multi-pixel array detection, adding the dimension of spatial parallelism. This allows the system to detect multiple photons simultaneously across different pixels, widening the detectable light-intensity range
2Adaptability or versatility
If strong light is incident on a PPD, then the light-intensity range is extended, but photon count loss occurs due to uneven photon distribution and response speed limitation
Solution Approach 1:
Each pixel in the PPD array has optimized local detection characteristics suitable for handling photon bursts. The uniform distribution of photons across multiple pixels ensures that no single pixel is overwhelmed, maintaining linear response even under strong light illumination
Solution Approach 2:
The invention introduces a beam diameter adjustment mechanism as an intermediary to match the incident light beam size with the effective detection area of the PPD array. This ensures uniform photon distribution across the detection elements, preventing photon count loss
3Measurement precision
If the beam diameter of light incident on the photodetector is made equal to the effective detection area, then photon count loss is reduced, but the device complexity increases due to the adjusting mechanism
Solution Approach 1:
The beam diameter adjustment mechanism dynamically changes the optical parameters (beam size) to match the detection area. This parameter optimization ensures maximum photon utilization while the adjustment can be implemented through simple optical elements like variable diameter apertures or lens positioning
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 apparatus effectively reduces photon count loss and expands the detectable light-intensity range from weak to intense light, ensuring high sensitivity across a broader range of light intensities.
Implementation Method 1
a collimator lens that converts the light collected by the objective lens into a substantially collimated beam
Implementation Method 2
a photodetector including a plurality of detection elements that detect the light collected by the objective lens
Data Source
AI summary
By using a PPD as a detector, photon count loss is reduced to the utmost, and the incident light-intensity range in which light can be detected is widened. Provided is a laser microscope apparatus including an objective lens that collects return light from a specimen; a collimator lens that converts the return light collected by the objective lens into a substantially collimated beam, a PPD including a plurality of pixels that detect the return light converted to a substantially collimated beam by the collimator lens; and a controller that makes the beam diameter of the return light incident on the PPD substantially equal to an effective detection area of the PPD, formed by the plurality of pixels.