Calibration

The Printalyzer UV/VIS Densitometer uses components that should provide stable readings over the lifetime of the device. However, to ensure measurement accuracy, calibration should be checked periodically.

A transmission step wedge, and a reflection step tablet, have been provided with the device for the purpose of performing and verifying calibration. These materials must be kept clean and should be stored in their envelopes when not in use. The basic layout of these materials, and their expected measurement locations, can be seen in Fig. 3.

Note: The read head must be firmly held down during all measurements to ensure accurate results. If the head is released during the process, calibration will fail.

Fig. 3 Calibration strip layout, showing measurement locations

VIS Reflection Calibration

• Press the [ ] buttons together to open the device menu

• Select “Calibration” and press

• Select “Reflection” and press

• Make sure that the numbers after “CAL-LO” and “CAL-HI” match the corresponding numbers on the provided reflection step tablet’s label

  • If either of these numbers do not match, then adjust them accordingly

  • Select with

  • Adjust the value with and

  • Accept with

• Select “** Measure **” and press

• Follow the on-screen instructions:

  • Position the center of the reflection step tablet’s CAL-LO patch in the read area, firmly hold down the sensor head , and press the button

  • Position the center of the reflection step tablet’s CAL-HI patch in the read area, firmly hold down the sensor head , and press the button

If using 3rd party calibration materials, the following guidance should be taken into account:

• The CAL-LO patch should have a marked density of 0.10 or less.

• The CAL-HI patch should have a marked density roughly within the range of 1.50 through 1.90.

• If the material was marked for color densitometer calibration, then use the values labeled as “visual” or “black.”

• The material must be held perfectly flat against the bottom of the sensor head to ensure accurate measurement. This is easy if the material is made from photographic paper, however it can be quite difficult if the material is made from a thick piece of painted metal.

VIS Transmission Calibration

Note: The provided transmission step wedge has separate numbers for “VIS” and “UV” modes. Please make sure to use the “VIS” numbers for this calibration process.

• Press the [ ] buttons together to open the device menu

• Select “Calibration” and press

• Select “VIS Trans.” and press

• Make sure that the number after “CAL-HI” matches the corresponding number on the provided transmission step wedge’s label.

  • If the number does not match, then adjust it accordingly

  • Select with

  • Adjust the value with and

  • Accept with

• Select “** Measure **” and press

• Follow the on-screen instructions:

  • With the read area empty, firmly hold down the sensor head and press the button

  • Position the center of the transmission step wedge’s CAL-HI patch in the read area, firmly hold down the sensor head , and press the button

If using 3rd party calibration materials, the following guidance should be taken into account:

• The CAL-HI patch should have a marked density roughly within the range of 2.90 through 3.00.

• If the material was marked for color densitometer calibration, then use the values labeled as “visual” or “black.”

• The material must be measured with the emulsion side facing upward towards the sensor. Whether or not the material is labeled this way may depend on the design of the densitometer it was originally intended for use with.

UV Transmission Calibration

Note: The provided transmission step wedge has separate numbers for “VIS” and “UV” modes. Please make sure to use the “UV” numbers for this calibration process.

• Press the [ ] buttons together to open the device menu

• Select “Calibration” and press

• Select “UV Trans.” and press

• Make sure that the number after “CAL-HI” matches the corresponding number on the provided transmission step wedge’s label

  • If the number does not match, then adjust it accordingly

  • Select with

  • Adjust the value with and

  • Accept with

• Select “** Measure **” and press

• Follow the on-screen instructions:

  • With the read area empty, firmly hold down the sensor head and press the button

  • Position the center of the transmission step wedge’s CAL-HI patch in the read area, firmly hold down the sensor head , and press the button

If using 3rd party calibration materials, the following guidance should be taken into account:

• The calibration reference must have patches that have been explicitly marked for UV densitometer calibration. Photographic film does not necessarily have the same density in the UV spectral range as it does in the Visual spectral range.

• The CAL-HI patch should have a marked density roughly within the range of 2.90 through 3.00.

• The material must be measured with the emulsion side facing upward towards the sensor. Whether or not the material is labeled this way may depend on the design of the densitometer it was originally intended for use with.

Sensor Gain

Sensor gain calibration is a process normally performed as part of device manufacture. As it should not normally need to be repeated by the user, the desktop companion software is required to perform it.

The purpose of sensor gain calibration is to determine the actual relationship between the various gain settings of the light sensor used by the device. This is necessary so that target readings taken at different levels of sensitivity can be accurately compared.

Sensor gain calibration is discussed in more detail in the Theory of Operation section, later in this manual. The process of actually performing sensor gain calibration involves the desktop software and is currently beyond the scope of this manual.

Sensor Slope

Sensor slope calibration is a process normally performed as part of device manufacture. As it should not normally need to be repeated by the user, the desktop companion software is required to perform it.

The purpose of sensor slope calibration is to ensure the linearity of the sensor’s response curve. This is necessary to ensure accurate readings at both low and high densities, while still only requiring two points to be measured as part of the user calibration process described above.

Sensor slope calibration is discussed in more detail in the Theory of Operation section, later in this manual. The process of actually performing sensor slope calibration involves the desktop software and is currently beyond the scope of this manual.