Apparatus for forming pattern

1. An apparatus for forming a pattern comprising:

a light source that emits a beam;

a scanning unit that scans the beam on a photosensitive material;

a beam position detector that measures a position of the beam on a scanning-line;

a fine-section scale corrector that changes the scale of a series of fine-sections to a series of corrected fine-sections in accordance with a scale-change rate to change a scale of a pattern, the series of fine sections being defined by dividing a scanning-line at constant-intervals;

a pulse data selector that selects a set of pulse data, corresponding to a length of the corrected fine section that the beam passes, from a series of sets of pulse data, the series of sets of pulse data having a different data-array in accordance with the length of the corrected fine section;

a control pulse signal generator that successively generates a sequence of control pulse signals in accordance with the selected set of pulse data;

a writing pulse signal generator that successively generates a sequence of writing pulse signals in accordance with the sequence of control pulse signals, the sequence of control pulse signals controlling the output-timing of the sequence of writing pulse signals; and

an optical modulator that modulates the beam in accordance with the sequence of writing pulse signals.

2. The apparatus of claim 1 , wherein said position detector detects the position of the beam by counting a pulse number of a sequence of standard clock pulse signals with a given frequency that is higher than a frequency necessary for counting a scanning-time corresponding to a dot-pitch.

3. The apparatus of claim 1 , wherein said fine-section scale corrector sets a writing start position for each fine section as a trigger position, and changes the trigger position to a corrected trigger position in accordance with the scale-change rate, said position detector successively detecting the position of the beam from adjacent corrected trigger positions.

4. The apparatus of claim 1 , wherein said fine-section scale corrector scales down the series of fine sections.

5. The apparatus of claim 1 , wherein said optical modulator comprises an AOM (Acousto-Optical Modulator).

6. The apparatus of claim 1 , wherein said scanning unit comprises a polygon mirror and an f−θ lens.

7. An apparatus for generating a sequence of control pulse signals comprising:

a beam position detector that measures a position of the beam on a scanning-line;

a fine-section scale corrector that changes a scale of a series of fine-sections to a series of corrected fine-sections in accordance with a scale-change rate, to change a scale of a pattern, the series of fine sections being defined by dividing a scanning-line at constant-intervals;

a pulse data selector that selects a set of pulse data, corresponding to a length of the corrected fine section that the beam passes, from a series of sets of pulse data, the series of sets of pulse data having a different data-array in accordance with the length of the corrected fine section; and

a control pulse signal generator that successively generates a sequence of control pulse signals in accordance with the selected set of pulse data.

8. A method for generating a sequence of control pulse signals comprising:

measuring a position of the beam on a scanning-line;

changing a scale of a series of fine-sections to a series of corrected fine-sections in accordance with a scale-change rate, to change a scale of a pattern, the series of fine sections being defined by dividing a scanning-line at constant-intervals;

selecting a set of pulse data, corresponding to a length of the corrected fine section that the beam passes, from a series of sets of pulse data, the series of sets of pulse data having a different data-array in accordance with the length of the corrected fine section; and

successively generating a sequence of control pulse signals in accordance with the selected set of pulse data.