(FILE No. A2-2) TO MEASURE NFP OF MMF (multi-mode optical fiber) USING 850nm LD LIGHT SOURCE
Measurement method of near field pattern of MMF (multi-mode optical fiber) by NFP measurement is shown below. As the light source, 850nm LD light source is used. As NFP measurement system, Synos' sophisticated optical beam NFP measurement optics / M-Scope type S, high resolution digital CCD detector / ISA011, objective lens / M-Plan Apo 20x, are selected and arranged.
MEASUREMENT SYSTEM BLOCK DIAGRAM
MEASUREMENT SYSTEM COMPONENT
- Optical beam NFP measurement system
- Light source (latest model)
- Objective lens
- Optical beam analysis module (latest model)
Result of MMF NFP measurement, using 850nm LD light source, is shown as left-hand image.
- Beam width
- Vertical 52.342um / Horizontal 52.940um（1/e2 width）
- Measurement condition
- Total magnification：20x (objective lens : 20x)
- Pixel resolution：0.2325um
- Dark current calibration：done
- Image integration：8 frames
In addition, from the acqcuired MMF NFP image, encircled flux analysis is done as shown in left-hand image.
- EF graph
- refer to left-hand image
- center：gravity of area
- Setting of analysis area criteria：30um
- Setting of analysis radius coefficient：1.15
- Setting of sampling pitch：0.1um
- Background calibration：done (coefficient 1.2)
POINTS OF SYSTEM SELECTION
- Optics selection
- As measurement optics, Synos' optical beam NFP measurement optics / M-Scope type S is selected. As objective lens, 20x is selected. As the result of this optics selection, real observation view is approx. 320um x 240um, and pixel resolution is approx. 0.23um.
- Detector selection
- As imaging detector, Synos' high resolution digital CCD detector / ISA011 is selected, because of having high resolution and sensitivity in 850nm region, good gamma characteristic, good durability against input light, etc.
- Objective lens selection
- As measurement wavelength is around 850nm range, standard type objective lens is selected.