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Lensometer using i.MX51 SOM


Well-known manufacturers and distributors of medical instruments based out of India. The client develops ophthalmic equipment, microscopes, lasers, microsurgical instruments and pharmaceuticals.


Lensometer is used by opticians to verify the prescription in a pair of eyeglasses, to orient, mark uncut lenses and to confirm the mounting of lenses in a spectacle frame. Lensometer is used to verify the power of contact lenses.

Key Features:

  • To find the following optical parameters and behaviours
    • Normal lens power
    • Contact lens power
    • Multifocal lens powers
    • Detect the Progressive lens
    • Progressive lens powers and add value
    • Prism power
    • Prism shift
  • The measurement range of sphere, cylinder and axis are
    • Spherical power => -25D ~ +25D
    • Cylinder power => 0 ~ ±10D
    • Axis => 1 ~ 180˚
  • The progressive lens addition value ranges from 0 ~ ±10D
  • LCD displays the power and attributes
  • LED is used to generate light towards the lens
  • The prism value ranges from 0 ~ 10Δ
  • Printer to print the data and image
  • software up-gradation by USB
  • Calibration and diagnostics

Solution offered by iWave:

There are four modules in the Lensometer.

  1. Image processing and Optical parameter calculations
  2. iMX51 SOM with carrier card
  3. Mechanical stand
  4. GUI for user

iWave has collaborated along with the client using its hardware, firmware and software expertise to bring about a kind of revolution in optical industry. Complex algorithms were developed to the precise measurements of the lens optical parameters.  iWave developed the application custom libraries specifically for this project.

Few of the algorithm worth a mention are:

  • Normal/contact/framed Lens centre identification
  • Progressive lens detection
  • Progressive lens far point identification
  • Progressive lens near point identification
  • Graph drawing algorithm for progressive lens
  • Prism shift value calculation
  • Measurement for prism
  • Lens location drawing algorithm
  • Calibration of lenses and Prism
  • Spherical power calculation
  • Cylinder power calculation
  • Axis calculation
  • Cylinder form formulas
  • Marking prism lens (X-Y coordinates)

The hardware components used in the Lensometer are:

  • Freescale i.MX51 800MHz Processor
  • NAND Flash and DDR
  • Thermal printer
  • 7’’ TFT LCD
  • LCD Brightness control
  • 5 key Keypad
  • RTC
  • USB2.0 Host
  • Analog camera interface

iWave’s i.MX51 custom module was seamlessly integrated with customer applications. Given iWave’s design Quality and Technical Support, client could easily adapt iWave’s SOM into their design. iWave provides i.MX51 processor module hardware and BSP support under one roof.

iWave’s in-house software BSP support clients to validate the end application quickly and achieve short product development life cycle and quick time to market.