Systems and associated processes for guiding users to provide more useful reviews are described. Methods for using the exchangers including methods that involve use of the exchanger and a reaction vessel to produce a reaction product gas containing trichlorosilane are also disclosed. A modulation control unit controls the mirror elements, whenever at least one pulse of illumination light is emitted, in a manner such that the optical elements spatially modulate the pulses of illumination light differently from one another and form substantially the same intensity distribution for the pulses of illumination light on a predetermined plane. Thus, contents regarding which the user has no interest are automatically deleted. In another embodiment, a retractable handle is disposed within the side periphery when in the retracted position.