Reduction of Laser Running Cost (Cost of Operation)

3. Reduction of the Cost of Consumable (CoC)

3-1. Actual Figures in CoC Reduction and Future CoC Reduction Plan
Figure 1 shows the reduction in CoC achieved since the first quarter of 2007 and the reduction plan through 2009 in percentage terms (assuming that the cost generated by consumables in the first quarter of 2007 was 100%).

Figure 1: CoC Reduction and Future CoC Reduction Plan

The cost of consumables can be reduced by extending the life of each module. The following sections describe the actual achievement in extending the life of consumable modules by the second quarter of 2008 and the future CoC reduction plan:

3-2. Actual Achievement in Extending the Life of Each Consumable Module

3-2-1.  Extending chemical filter life
Since the second quarter of 2007, the life of a chemical filter has been extended from one year to the maximum of 3 years.* The cost required for replacing a chemical filter is less than that for other consumables. But because the chemical filter is one of the modules with a shorter life, extension of its life is very meaningful from the viewpoint of not only CoC but also CoD.

* The chemical filter life is determined by the purity of N2 purge gas in the laser-installed environment.

3-2-2.  Extending chamber life
Since the second quarter of 2007, the lives of the OSC chamber and that of the AMP chamber for the GT40A/GT50A have been extended from 13 to 20 billion pulses (Bpls) and from 19 to 30 Bpls, respectively. This has been achieved by applying the life extension technology introduced to the GT61A to the existing model GT40A. This results in the use of a common platform that allows introduction of new technologies to the existing models.

The chamber cost accounts for a large percentage of the cost of consumables. Thus, extension of chamber life enables a great reduction of 26% in CoC.

3-2-3.  Extending AFM/ARM life
Since the second quarter of 2008, the life of the AFM/ARM (Amplifier Front Mirror/Amplifier Rear Mirror) has been extended from 12 to 30 billion pulses (Bpls). This is not included in the cost reduction plan as of 2007, but the actual life of AFM/ARM in the field has been studied again to achieve extension of its life. This has allowed a 34% cost reduction in the second quarter of 2008, compared with the figure in 2007.

3-3. Future CoC Reduction Plan
Gigaphoton aims at further reduction in CoC by introducing the following new technologies to its laser products:

3-3-1. MPL
We at Gigaphoton will introduce the Multi-Positioning Line-Narrowing Module (MPL) in the third quarter of 2008 to extend the life of the line-narrowing module (LNM) from 40 to 60 billion pulses (Bpls). Figure 2 shows the concept of the MPL.

The LNM consists of optical components such as a prism and a grating. These optical components will deteriorate when a laser beam is transmitted through or reflects on them. As these optical components deteriorate, the transmittance/reflectance drops to lower the efficiency of the LNM. If this efficiency becomes below a threshold, the LNM needs to be replaced.

As shown in figure 2, the MPL first uses the optical path shown in red and then uses another optical path shown in yellow by moving the LNM downward. This allows recovery of the LNM efficiency, thus extending the LNM life.

Figure 2: MPL Concept
Figure 2: MPL Concept

3-3-2.  GRYCOS
The Gigaphoton Recycled Chamber Operation System (GRYCOS) will be introduced in 2008. GRYCOS allows use of the chamber for up to 40 billion pulses (Bpls), thus reducing the chamber cost. Figure 3 shows the GRYCOS concept.

Figure 3: GRYCOS Concept

Gigaphoton’s GT series products use the same hardware for both oscillator (OSC) and amplifier (AMP) chambers. In addition, the life of OSC chamber becomes shorter than that of the AMP chamber because the OSC chamber is line-narrowing the laser (OSC chamber life = 20 Bpls, AMP chamber life = 30 Bpls). Though the current AMP chamber life is 30 Bpls, it is so designed as to have sufficient margin. Therefore, the actual life of the AMP chamber is estimated at 40 Bpls. Using this feature, GRYCOS uses the OSC chamber that has reached its life of 20 Bpls as the AMP chamber and uses it for another 20 Bpls. As a result, each chamber can be used until it has reached 40 Bpls, thus allowing reduction in the number of chambers used by up to 2/3 from the conventional use method.

As described above, the chamber cost accounts for a large percentage of the cost of consumables. Introduction of GRYCOS allows great reduction in CoO.

We at Gigaphoton conducted an in-house test on the GRYCOS performance. Used the chamber used as an OMC chamber as the AMP chamber up to a total of 40 Bpls, we checked all the performance items and confirmed that there is no problem with these items. Table 1 shows its test result.

Table 1: Major Performance Check Result
Items Performance Specification OK/NG
Total Chamber pulse 40.4 Bpls 40Bpls OK
AMP Chamber pressure 249kPa <420kPa OK
AMP HV 20.04kV <23kV OK
Energy stability 0.08% <0.15% OK
WL stability 0.007pm <0.012pm OK
Spectrum E95 0.34pm <0.50pm OK

3-3-3.  Cost reduction effect
We are aiming at 52% of cost reduction by 2009 by introducing the MPL and GRYCOS as described above (see figure 1).

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