Product

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

Background

The objective of the laser uniformity calibration test is to verify that all laser dioes are working properly and output matching visual results.

Each laser diode must produce a clean screeen that is free of jitters, unexpected patterns, and differences in dot shape.

Requirements

Tools:

• Densitometer
• Microscope
• Plates

Prerequisites:

• Focus value obtained in the Focus calibration test
• Elevation angle obtained in the Elevation adjustment procedure
• Intensity value obtained in the Intensity calibration test
• Resolution value obtained in the Resolution calibration test
• Drum speed obtained in the Drum speed calibration test
• Delay value obtained in the Delay calibration test

Procedure

This procedure includes the following sections:

• Before you begin
• Calibrating uniformity

Before you begin

• Verify the following conditions:
  • all the laser ddb factors are set to 0.
  • In the registry, under EXPOSE, the Laser Factor From Host Enable parameter is set to 0.
    

Calibrating uniformity

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 Laser Uniformity.
   2. In the Drum Speed field, type the value that you found in the Drum speed calibration test.
   3. In the Intensity Factor Values [%] area, in both the From and To fields, type 0.
   4. In the Number of Steps list, select 1 step.
      
   5. In the Resoluton list, select the resolution used by the customer.
   6. In the Current Plate list, select the plate that you are using for the test.
   7. 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.
   8. 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 laser uniformity test.
   The Lotem/Magnus 400 Controller software performs a series of exposures on the plate, after which you need to process the plate and examine the results.
   
5. Visually examine the results to see if the lasers work and produce a clean screen (no slashes, patterns, shifts, extra dark or bright solids, and so on). If you are not satisfied with the results, repeat the test. If all tests produce the same results, the diode is faulty.

   Because a diode that is not working properly might influence adjacent diodes, first replace only the diodes that produce effects such as patterns, and those that produce a much darker solid than the surrounding diodes.
   
   
   Diodes that are dark solids

6. If all lasers work and produce a clean screen, continue with the resolution calibration test.
7. If one or more lasers do not work properly, or do not produce a clean screen, replace that/those diode(s), and repeat the laser uniformity test.

Technical contact

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

Date submitted

11 Jun 2008