Manuals - Bulletins - Drawings
Features
- Real-time sarcomere length measurement from video signal at up to 2,200 frames per second
- Calculates sarcomere length accurately even with small sample regions and poor image quality
- Two length calculation methods: FFT and Autocorrelation Function/Sine-fit
- Complete System including: HVSL Software, PC, CCD Camera, camera interface card, all required cables.
- Easy to use calibration menu that provides two calibration methods: Field of View or Calibrated Length
- Scope module - real-time scrolling data display that stores up to 2 hours of sarcomere length data, can also log data to disk at up to 1,000 samples per second.
- Record and Playback Functions that allow high-speed streaming to disk and calculation of sarcomere length from image files.
- Image Capture and SL data output can be controlled by 600A Digital Controller.
- Output of SL data to ASI 600A Digital Controller
- SL control when used with 600A Digital Controller.
The 901A High-speed Video Sarcomere Length (HVSL) system will acquire images and calculate sarcomere length at up to 2,250 frames per second. The system includes the HVSL software, a control PC, a camera interface, all required cables and a high-speed CCD camera capable of providing full-frame images at 210 frames per second. With smaller regions of interest (ROI) the camera can provide images at up to 2,200 frames per second. In addition to real-time sarcomere length (SL) measurement, the software can also be used to stream images to disk and to calculate SL from captured image files.
The software includes a Scope function that provides a scrolling data display of sarcomere length with time. This display can record up to 2 hours of sarcomere length data. The Scope display can be frozen at any time and the user can then scroll through the sarcomere history. Scope can also log SL data to disk at rates of up to 1,000 samples per second.
The HVSL software and hardware operates on a dedicated Linux PC. For ease of calibrating the system the HVSL software provides two calibration methods, Field of View and Calibration Length. Image brightness and contrast are controllable through the software.
Advanced Measurement Algorithms
The High-speed Video Sarcomere Length program includes two length calculation methods: AutoCorrelation Function (ACF)/Sine-fit and Fast Fourier Transform (FFT) with curve fit. The ACF method calculates the autocorrelation of each scan line and then calculates the average over the ROI. For periodic images the result resembles a sine wave. The ACF/Sine-fit method fits a sine function to the average ACF to determine sarcomere length.The FFT method calculates an FFT for each scan line in the Region of Interest (ROI). The average is computed, the peak identified and then a quadratic curve is fit to the spectrum around this peak. The location of the maximum of this curve provides the sarcomere length.
The ACF/Sine-fit provides the most robust and accurate method of determining sarcomere length. With this technique the measurement resolution is not dependent on the size of the ROI or on the number of cycles in the ROI. Traditional FFT methods produce a coarse measurement of sarcomere length when the optical magnification and ROI result in a small number of sarcomeres present in the image. This is not the case with the ACF/Sine-fit method which maintains length resolution even with small sample size or small number of sarcomeres in the image.
Additionally, the ACF/Sine-fit algorithm also handles noisy or poor images better than the FFT method. This is due to our technique of calculating the FFT of the ACF function, removing peaks outside of the expected range of sarcomere lengths and then calculating the inverse FFT. The resultant series is a filtered version of the ACF and has most of the noise removed from it. The sine-fit is then performed on this series.