How are characters' inner conflicts intensified by the imagery of light and darkness in Macbeth?

In Macbeth, there are many instances of the imagery of light and darkness. Light symbolizes clarity, goodness, and incorruptibility. Darkness, however, embodies impurity, evil, and corruption. 

Light and darkness are both employed to intensify the inner conflict of the major characters or the atmosphere in the country. I will list a few examples below.

1. When King Duncan declares Malcolm to be his successor, he speaks about the honor of other warriors in terms of light:

Malcolm, whom we name hereafter
The Prince of Cumberland; which honour must
Not unaccompanied invest him only,
But signs of nobleness, like stars, shall shine
On all deservers.

Duncan states that all those who have displayed valor, honesty and loyalty will be rewarded. Light is seen as good. Therefore, Duncan can be seen as a character standing up for true values. 

2. Darkness, unlike light, symbolizes evil. When Macbeth begins to succumb to his ambitions, he begins to accept darkness:

The Prince of Cumberland! that is a step
On which I must fall down, or else o'erleap,
For in my way it lies. Stars, hide your fires;
Let not light see my black and deep desires...

His "black and deep" desires are evil and sinful because he wants to kill his relative and king in order to take the throne. His conscience attempts to warn him against these perilous desires, but Macbeth, guided by his ambition, pressured by his wife, and encouraged by the witches' prophecies, decides to embrace evil.

3. When Macbeth commits murder, we notice strange occurrences in nature. Disorder begins to take control of Scotland:

By the clock, 'tis day,
And yet dark night strangles the travelling lamp.

This disorder is shown through the image of darkness. 

4. In Act V, Scene 1, we see the perilous force of darkness and its effect on others. Lady Macbeth, who once summoned darkness, now demands light:

She has light by her
continually; 'tis her command.

Having realized darkness makes her fragile, Lady Macbeth no longer wants it. She realizes murdering Duncan is a bad idea, and continues to be haunted by it. Unfortunately, her realization is too late, and she soon succumbs to her death.