"Please check permissions" error message with USB DAC

Error message "Error setting mirror, please check permissions" may appear when trying to control the deformable mirror with USB DAC in FrontSurfer or OKO DM control software. The problem may be caused by incompatible FTDI driver versions installed by Windows and the software. To deal with it, please proceed as follows:

  1. install updated driver from
  2. go to C:\Program Files (x86)\OKO_DM_Ctrl or (C:\Program Files (x86)\FrontSurfer1.4.10.dm) and change the name of ftd2xx.dll to ftd2xx_bu.dll for backup purposes;
  3. go to C:\Windows\SysWOW64 and copy ftd2xx.dll from it to C:\Program Files (x86)\OKO_DM_Ctrl or (C:\Program Files (x86)\FrontSurfer1.4.10.dm folder.

    C:\Windows\SysWOW64 is the default directory where 64-bit windows keeps libraries for 32-bit applications; please modify it if your installation is different