Instruction manual

Chapter 3 Operation Details

3.19.2 Excitation light filter (EX filter)

An excitation light filter transmits lights selectively and

blocks other lights. The transmitted lights are called

excitation lights. They are used to excite the

fluorophore in the sample and fluorescent lights are

emitted from the sample. The wavelength range of

lights that can pass through the filter is called the

bandwidth.

The bandwidth of the excitation light filter determines

the brightness of the fluorescent image, the

occurrence of autofluorescence (fluorescence

resulting from substances other than the

fluorophores), and degree of fading. When the filter

has a wide bandwidth, a large amount of excitation

lights will be irradiated on the sample. In this case,

the image becomes bright but the amount of

autofluorescence becomes large and fading of the

sample occurs soon. On the contrary, when the filter

has a narrow bandwidth, a small amount of excitation

lights will be irradiated on the sample. In this case,

the image becomes dark but the amount of

autofluorescence becomes small and fading of the

sample occurs late. For samples with pronounced

autofluorescence, use an excitation light filter with a

narrow bandwidth. (The resulting fluorescent image

will be darker, however.)

The excitation light filter is exposed to strong lights.

Therefore it may deteriorate under use. Please

replace it at a proper interval based on the hours

used.

Narrow Bandwidth of excitation filter Wide

Brightness of

fluorescence image

Dark Bright

Occurrence of

autofluorescence

Less frequent Frequent

Degree of fading Small Large

EX filter

Bandwidth

Wavelength

Spectral

transmittance