Filter set, system, and method for observing protoporphyrin IX

A filter set, comprising:

• an illumination light filter;
• and
• an observation light filter,
• wherein a transmission characteristic of the illumination light filter is a sum of a first partial characteristic and a second partial characteristic,
• wherein a transmission of the first partial characteristic within a first wavelength range, which lies below a limit wavelength, is greater than a first value,
• wherein a transmission of the second partial characteristic within a second wavelength range, which lies above the limit wavelength, is greater than the first value,
• wherein a transmission characteristic of the observation light filter is a sum of a third partial characteristic and a fourth partial characteristic,
• wherein a transmission of the third partial characteristic within a third wavelength range, which lies above the limit wavelength, is less than a second value and greater than a third value,
• wherein a transmission of the third partial characteristic within a ninth wavelength range, which lies above the third wavelength range, is greater than the first value,
• wherein a transmission of the fourth partial characteristic within a fourth wavelength range, which lies below the limit wavelength, is less than the second value and greater than the third value,
• wherein a transmission of the illumination light filter within a fifth wavelength range, which lies between the first wavelength range and the second wavelength range, is less than a fourth value,
• wherein a transmission of the observation light filter within a sixth wavelength range, which lies between the third wavelength range and the fourth wavelength range, is less than the fourth value, and
• wherein the fourth value is less than the third value, the third value is less than the second value, and the second value is less than the first value.

A filter set, comprising:

• an illumination light filter;
• and
• an observation light filter,
• wherein a transmission characteristic of the illumination light filter is a sum of a first partial characteristic and a second partial characteristic,
• wherein a transmission of the first partial characteristic within a first wavelength range, which lies below a limit wavelength, is greater than a first value,
• wherein a transmission of the second partial characteristic within a second wavelength range, which lies above the limit wavelength, is less than a second value and greater than a third value,
• wherein a transmission characteristic of the observation light filter is a sum of a third partial characteristic and a fourth partial characteristic,
• wherein a transmission of the third partial characteristic within a third wavelength range, which lies above the limit wavelength, is greater than the first value,
• wherein a transmission of the fourth partial characteristic within a fourth wavelength range, which lies below the limit wavelength, is less than the second value and greater than the third value,
• wherein a transmission of the illumination light filter within a fifth wavelength range, which lies between the first wavelength range and the second wavelength range, is less than a fourth value of 0.005%,
• wherein a transmission of the observation light filter within a sixth wavelength range, which lies between the third wavelength range and the fourth wavelength range, is less than the fourth value,
• wherein the fourth value is less than the third value, the third value is less than the second value, and the second value is less than the first value,
• wherein the limit wavelength lies between 450 nm and 550 nm,
• wherein the first wavelength range lies between 350 nm and the limit wavelength,
• wherein the second wavelength range lies between the limit wavelength and 680 nm,
• wherein the third wavelength range lies between the limit wavelength and 800 nm, and
• wherein the fourth wavelength range lies between 410 nm and the limit wavelength.