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The laboratory technician calibrates the system when needed by adjusting camera settings and analyzing an imaged Xrite Color Checker Standard (MacBeth card) or a QP 101 V4 Color Standard. The current light system obtains nearly uniform illumination intensity from the core’s surface (half or whole round) to the bottom of the liner by a combination of high intensity, overlapping large diameter light source, close coupling to the imaged surface and the “line” image plane. The bottom edge of the brass led mount should be set between 2 and 4cm from the image surface. For uneven hard rock cores the height can be set higher but illumination intensity will drop, exposure times lengthen, f-stop opened and scanning speed reduced. Note, any height change to the lights requires re-calibration. Heat is removed from the LEDs and transferred to the surrounding air via the copper heat pipes and is cooled with mini fans. While these to the copper rods can get hot they are not a burn hazard. However they are very delicate and bend at the slightest touch, so use care when working with the camera lens. For more detailed information on the theory behind the calibration please refer to the Understanding the SHIL Calibration for further reading. Maintain temperature of the lights at 30-35 °C during calibration.
Note: the following instructions are divided into 2 sections. Calibration Check and Calibration.
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- These lights can get hot if the cooling fans are not used. The temperature is shown on the read out above the camera and is maintained at a temperature of 30 °C. During a section scan, the temperature will range between 30 and 35 °C. If Temperature goes above 50°C an alarm will sound. Notify a technician if alarm sounds. Caution is needed when technicians perform the calibration process . Here, because the lights are stationary and you must be conscious of the temperature of the lights. You can use the manual power switch to turn the lights on and off or the buttons in the software (procedure below uses buttons in software). Use the heat resistant grey silicone mat for the shading and pixel corrections. Do not use the plastic Gray card. Make sure the temperature is maintained between 30 and 35°C for calibration (to match temperature of lights during imaging of a section).
- Never look at the LEDs directly. Even the reflected light can be painful. When working under the track make sure that the power is off.
- NOTE: if you are concerned with the heat dissipation on the core surface, you can use our FLIR cameras to confirm that the temperature is ok.
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