Hayabusa LIDAR Calibration Description

LDR_SIG_RAW (DU) in HK and OBS packet

  This is counted value of received or transmitted power.
  LIDAR can monitor only 1 channel, receiving or transmitting.
  Transmitting and receiving power were calibrated by following equations.

  * Transmitting power: Pt (mJ) = Transmitting count value (0-255) x 1.4303
                                  + 32.497

  * Receiving power: Pr (10^-15 J) = Receiving count value (0-255) x 0.05
    ( circuit gain = high, sensitivity (APD) gain = high )

  Pr = Pt x (A x D^2) / (32 x R^2) x T_sys
    A: albedo of asteroid Itokawa
    D: efficient diameter of receiving reflecting telescope (126 mm)
    R: distance between spacecraft and asteroid
    T_sys: transmissivity of optical system