Product

• Kodak^® Lotem^® 400 FH family
• Kodak Magnus^™ 400 LDA family
• Kodak Magnus 400 II LDA family

Background

The objective of the resolution calibration test is to calibrate the optical head so that the distance between two adjacent laser dots corresponds with the file resolution.

Perform the test using a resolution of 100 dpm, and repeat the test for all resolutions used by the customer.
Note: The resolution test results do not depend on the plate type, size, or thickkness; perform the test on any plate that the customer uses.

Requirements

Tools:

• Densitometer
• Microscope
• Plates

Prerequisites:

• Focus value obtained in the Focus calibration test
• Intensity value obtained in the Intensity calibration test

Procedure

This procedure includes the following sections:

• Calibrating resolution
• Selecting the correct resolution

Calibrating resolution

1. Load a plate.
2. From the Kodak Xpo^™ palette, select Tools > Calibration.
   
   
   
   
3. In the Calibrate dialog box, perform the following steps:
   1. In the Calibration Type list, select Resolution.
   2. In the Motor Value field, do not change this value until the optimal resolution has been determined. See Selecting the correct resolution.
      Note: To load the last-saved motor test value, click Get.
   3. In the Test Motor Values [steps] area, in the From and To fields, type the test range for the resolution stepper motor values. For best results, enter a range that is ±100 motor steps of the currently displayed motor value—for example, from 1000 to 1500.
   4. In the Number of Steps list, select the number of exposures to perform for the selected test resolution value range. For best results, enter a minimum of 10 or 11 steps.
      When you type a step value, the Lotem/Magnus 400 Controller software automatically calculates and displays the size of each step interval in the Size field, using the following formula:
      Step size = (To–From)/(Number of steps –1)
      Note: The interval value provides a quick reference for the platesetter operator, and cannot be changed.
   5. In the Resoluton list, select the resolution used by the customer.
   6. In the Test File list, select the TIF file that you want to use for the resolution test.
      Note: Test files are predefined; the ones that appear in the list are according to the selected resolution.
   7. In the Current Plate list, select the plate that you are using for the test.
   8. In the Image Offset fields, type a value in millimeters for the horizontal offset (around the drum), and the vertical offset (along the drum).
      Note: The (0,0) offset coordinate is located at the upper-left corner of the plate.
      If you use the same plate for multiple tests, enter the appropriate offset values for each test.
   9. In the Plate Policy section, select or clear the Load and Unload check boxes that apply to focus test:
      • Load: Automatically loads a new plate before the test begins. To perform multiple calibration tests on the same plate, before you start the next test, clear this check box to reuse the plate.
      • Unload: Automatically unloads the plate after the test. To perform multiple calibration tests on the same plate, before you start the next test, clear this check box.
4. Click Test to start the resolution test.
   Lotem/Magnus Controller performs a series of exposures on the plate, after which you need to process the plate and examine the results.

Selecting the correct resolution

1. Visually examine the results, and select the target strip that has no vertical lines, slashes, or other artifacts in the 50% dot area.
   
   
   
   

   Using a microscope, examine the vertical 2P section of the selected target. Look for the most even and solid (100%) swaths that have equal widths of two pixels. Evenly spaced swaths indicate correct resolution.
   
   
   
   

2. In the Motor Value field, type the optimal motor value returned, and click Save.
3. Verify that the new value was saved in the database.
   1. In the Lotem/Magnus 400 Controller software, in the Hardware tree, go to DataBase, and double-click Res Motor.
      
      
      
      
   2. In the Resolution Motor Tables dialog box, in the Res Motor column, the newly-saved value should appear next to the selected resolution.
   3. Click Close.
4. If required, repeat the test for other resolutions used by the customer.

Technical contact

Content owner: Mario Amir
See the Escalation page for escalation contacts.

Date submitted

11 Jun 2008