Control apparatus and control method

A control apparatus for an optical apparatus equipped with at least one light detector configured to detect light from a pattern surface of a photomask that is illuminated by illumination light and on which a pellicle is mounted, the control apparatus comprising:

• at least one memory storing instructions;
• and
• at least one processor coupled to the at least one memory and configured, by executing the instructions, to:
• acquire pellicle information including a transmittance of the pellicle with respect to the illumination light;
• and
• set, based on the transmittance, a charge accumulation time of the at least one light detector when illuminating the pattern surface,
• wherein the at least one processor is further configured, by executing the instructions, to:
• set the charge accumulation time for a lower transmittance compared to a higher transmittance to be greater than the charge accumulation time for the higher transmittance, and
• set the charge accumulation time to be less than an upper limit value based on at least one of an intensity of the illumination light, a heat resistance performance of the pellicle, and a heat dissipation performance of the pellicle.

A control method of an optical apparatus equipped with at least one light detector configured to detect light from a pattern surface of a photomask that is illuminated by illumination light and on which a pellicle is mounted, the control method comprising:

• acquiring pellicle information including a transmittance of the pellicle with respect to the illumination light;
• and
• setting, based on the transmittance, a charge accumulation time of the at least one light detector when illuminating the pattern surface,
• wherein setting the charge accumulation time involves setting the charge accumulation time for a lower transmittance compared to a higher transmittance to be greater than the charge accumulation time for the higher transmittance, and setting the charge accumulation time to be less than an upper limit value based on at least one of an intensity of the illumination light, a heat resistance performance of the pellicle, and a heat dissipation performance of the pellicle.