Optical writing device obtaining a constant amount of pass-through light

An optical writing device comprising:

• a plurality of writing light shutter elements used for optical writing, said writing light shutter elements being made of an electro-optical material and are aligned in a main scanning direction;
• at least one monitoring light shutter element which is made of the electro-optical material and is separate from the writing light shutter elements;
• a driving unit which drives said writing light shutter elements and said monitoring light shutter element, said driver being capable of impressing a forward electric field and a reverse electric field to said writing light shutter elements and said monitoring light shutter element;
• measuring means for controlling said driver to impress at least one of the forward and reverse electric fields to said at least one monitoring light shutter element, and for measuring a half-wavelength voltage of said monitoring light shutter element impressed at least one of the forward and reverse electric fields;
• and
• controlling means for determining an impression ratio of the forward electric field and the reverse electric field based on the measuring result of said measuring means.