Measurement method:

The entire measurement chamber includes a plastic water tank and a lens support. The diameter of the lens support is known, and the ultrasonic probe is inserted from below the lens support, aimed at the inner surface of the lens. The focal point of the focused sound wave emitted is located at the center of the support. The lens holder is covered with a very thin plastic film, and the plastic water tank is filled with salt solution. As long as the concave surface of the corneal contact lens under test is placed on the support, the plastic film becomes the reference position for the sagittal height.

During measurement, the ultrasound probe generates a sharp focused ultrasound energy short pulse that penetrates the salt solution. Part of the energy from this pulse will be reflected back to the probe from the plastic film, the inner surface of the lens, the outer surface of the lens, and the surface of the salt solution. At this point, the thickness gauge will record the entire echo and accurately measure the time interval between the * echo and the second echo, as well as the time interval between the second echo and the third echo. (The fourth echo corresponds to the reflection on the surface of the salt solution, which is ignored here.)

*The time interval between the second echo and the second echo is proportional to the distance (i.e., vector height) between the plastic film and the inner surface of the lens, and the time interval between the second echo and the third echo corresponds to the thickness of the lens. The sagittal height and thickness of the lens can be calculated using formulas.

The curvature radius of the base arc can be calculated using a formula.

You can get it here1-Yagao,2-Center thickness,R-Base arc curvature radius

Calibration:

anyThe accuracy of ultrasonic measuring equipment depends on calibration. The accuracy of corneal contact lens measurement depends on the transmission speed of sound waves in salt solution and the specific lens material. Please note that the sound wave velocity in salt solution will significantly change with temperature and concentration, and the sound wave velocity in the lens will also be affected by temperature and lens composition.

The recommended calibration method is to measure a sample with a known base arc and center thickness at a constant temperature, and then calibrate the sound waves of the ultrasonic thickness gauge. With good calibration, the error range of vector height and center thickness can be controlled within+/- 0.01 mm.

Product composition

• *Penetrating high-precision multi-layer ultrasonic thickness gauge
• * Micro water immersion focusing probe and connector
• * Multi layer measurement software (excluding)PC）
• *Measurement chamber: including acrylic measurement chamber and lens support
• *Fixture system: including adjustable positioning device and four fixtures
• *Fixture includes: Universal tilting fixture (black)+White), Quick Fixture (Black)+White)

Main technical parameters

• *Thickness measurement range: 0.08~635mm (depending on material and probe configuration)
• * Material sound speed range: 0.508 mm/μ s～13.998 mm/μs
• * Resolution: Low resolution 0.1mm, standard resolution0.01mmHigh resolution (optional) 0.001mm
• * Probe frequency range: Standard: 2.0 MHz～30 MHz（–3 dB）
• * Detection: full wave, RF wave, positive half wave, negative half wave
• * Measurement layer: 4 layers (multi-layer software option)
• * Having differential mode and reduction rate mode
• * Time base BScanning mode, each scan can obtain10000 traceable readings
• * High dynamic gain technology with digital filters
• * Output interface: MicroSD，USB，RS232， VGA
• * Built in data recording: 475000A thickness measurement reading, or20000 waveforms with thickness values
• * Protection performance: IP67
• * Power supply: AC/DCAdapter,24 VLithium ion batteries,23.760 Wh; or4jointAA auxiliary battery.
• * Adjustable range of fixture height:0~15mm
• *Quick fixture aperture: 15mm step hole