Firma:                   Lebold

Modell:                OMS 3000/M

Kommentar:        Dokumente deut.

The system consists basically of:

• the optomechanical part OMS 3000 M (rack module with chopper, lamp, monochromator, detector, etc.)
• the electronical part OMS 3000 E (indication, operation and Signal processing)
• the feed throughs at the vacuum
  chamber with the light fibers

What OMS 3000 makes possible

Optical thin-film coatings are becoming increasingly important in industrial processes, as well as throughout the entire field of "high technology".

Various applications require high-precision specialized films or multilayer coatings for precise functions such as:

• Transmittance
• Reflectance
• Absorption
• Scattering
• Resistive to high temperature and moisture
• Abrasion resistance, adhesion

Multilayer coating systems used for beam­spitters, color conversion filters, bandpass, and heat protection filters, and for cold­light and laser mirrors, have to be produced to extremely tight tolerances

The tight specifications which are required for modern laser components and precision optics can only be met by using precise optical monitoring methods. The optical monitoring system has to supply a high signal resolution over a large measuring interval, excellent reproducibility and long­term stability. Besides this, the optical monitoring system should be user-friendly and offer easy maintenance of all components. A straigtforward light measuring instrument with an AC­amplifier is no longer sufficient for up to date requirements.

Thus, LEYBOLD has developed the OMS 3000, a new computer-based process photometer. It allows the precise cut off of the deposition of layers through the measurement of the changing reflectance or transmittance of separate test glasses or of the substrates themselves.

Major features

• Low long-term photometric drift
• Simple maintenance
• Dual-beam design based on flexible fiber optics
• High signal resolution
• Automatic setting of amplifier gain and calibration of reflectance and transmittance
• Display or results in units of percentage transmittance or reflectance with a resolution of 0.01 or 0.001 % respectively
• The operator feeds the relevant process parameters into the computer
• Automatic determination of related instrumental parameters
• The expected photometric curve is computed and analyzed in advance
• The trigger point (cut off) is corrected in real time
• Full support of all standard monitoring strategies
• Movings substrates measurable in intermittent mdoe
• Material's refractive index is automatically determined and displayed upon passing the A/4-turning point for single-layer coatings
• The spectral curves of reflectance or transmittance are measurable between two layers.

Where the OMS 3000 is used

Application areas

The OMS 3000 performs reflectance or transmittance measurements.

A major application is the real>time process control during the deposition of optical coatings. Both coninuous measurements on stationary substrates and intermittent measurements on moving substrates positioned on rotary carriers are possible. The monitoring software ensures reliable automatic film>thickness cut off during the deposition process. Computation of cut>off conditions and optimal setting of instrumental parameters (amplifier gain, time constant etc.) are performed automatically.

Real time trigger>point correction provides for high precision of layer thickness and excellent reproducibilities.

A stepper>motor controlled monochromator integrated into the standard instrument permits accurate measurements of complete reflectance or transmittance spectra. This leads to the following set of application areas:

• Reflectance or transmittance spectra taken under vacuum and in the air can be compared. Curves obtained may be edited (via a RS 232 C serial interface) by a plotter accepting standard HP>protocols.
• During a coating process the spectral curves can be measured between the deposition of two layers. The resulting data may be used for performing an on>line optimation, for this purpose the OMS 3000 can communicate with a PC via its RS 232 C serial interface.
• Quality control in production. Measured spectral curves may be processed by PC and compared with the given specifications. Where the OMS 3000 is used
• Film checking and monitoring in in­line coating systems. The excellent long-term stability of the OMS 3000 allows it to operate continuously over long time periods without recalibration.
• A specially developed measurement head equipped with an integrating sphere yields stable reflectance measurements on moving substrates.

Method of measurement

The OMS 3000 is a double-beam

photometer built in lock-in technology. It features light fibers to obtain inaccessible measuring points.

Fig. 1.1: Double beam measuring principle with fiber optic

1 Vacuum chamber

2 Feed through

3 Light fibers

4 Chopper

5 Lamp

6 Light barriers

7 Chopper motor

8 Stepping motor (for monochromator)

9 Grating monochromator

10 Detector

Transmission and reflection measurements can be performed in intermittent and in stationary mode.

Technical data

Optical Data

Light Sources

Halogen lamp, 12V/50W, approx. 1000 hours operating life, 400 nm - 2,400 nm useful wavelength range

Deuterium lamp (not yet available), 30W, approx. 1,500 hours operaing life, 200 nm - 400 nm useful wavelength range

Grating Monochromators

Stepper-motor controlled for use over 6 operating ranges

Model              Blocking      Wavelength

                      filter              Range

SMC 1-02      -                    200-400 nm

SMC 1-03      -                    400-800 nm

SMC 1-04      -                    450-900 nm

SMC 1-04      RG 610        600-1100 nm

SMC 1-05      Si                  1000-1800 nm

SMC 1-06      Ge                1700-2400 nm

Linear Dispersion (Standard)

4.5 nm/mm in the UV spectral range, 6nm/mm in the VIS-spectral range, 1 0 to 30 nm/mm in the NIR-spectral range

Detector

Silicon (standard), 400 - 1,100 nm useful wavelength range

Lead sulfide (optional), 1,100 - 2,400 nm useful wavelength range

Photomultiplier (not yet available) (optional) 200 - 900 nm useful wavelength range

Light Coupling

Fiber-optic bundle, 2.3 mm dia., NA= 0.22, acceptance angle = 25.5°, Measurement ranges: UV-fibers: 200-1200 nm, NIR­fibers: 400-2400 nm

Optical Feedthrough with Coupling

Optics

Available on special order

Signal Resolution

0.01 % referred to 100 % R or T for R or T > 10 %

0.001 % referred to 100 % R or T for R or T < 10 %

Noise/Signal Ratio

Dependent upon wavelength range and system signal yield, standard is the same as signal resolution

Long-Term Stability

1 % per week instrumental drift

Chopper Frequency 13 Hz

Interfacing

Data Entry Keypad with 8 keys

Display

5" monitor screen

Host-Computer Interfaces

RS 232 C and multibus-compatible bus interface

Recorder Outputs

0 - 10 V corresponding 0 - 100 % R or T

0 - 10 V with programmable resolution

External Control and Processing Parallel interface with three potential free digital inputs and four potential free digital outputs for integration into a "non­intelligent" automatic

Electrical Supply

OMS                              3000 M                OMS 3000 E

Voltage                          220 V ± 10 %       220 V ± 10 %

Frequency                     50/60 Hz               50/60 Hz

Power Consumption      150 VA                  70 VA

Dimensions

OMS                              3000 M                OMS 3000 E

Height                            265 mm                133 mm

Width                             325/295 mm        450 mm

Depth                            500 mm                350 mm

Weight                           23 kg                    8 kg